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NI ELVIS Computer-Based Instrumentation

1. Lab 5 The Study of Vibration 135 43 Resonance Vibrations vi Block Diagram File Edit View Project Operate Tools Window Help A Dn Q es bal P ot 15pt Application Font o AE Figure 5 13 The Resonance Vibration Diagram The Feedback Node alongside Build Array was used to visualize the raising of the resonance curve point by point The graphical representation is realized on the XY Graph called Resonance see Figure 5 12 In the Panel set the values for Start Frequency Hz Stop Frequency Hz and Horizontal and Trigger controls as shown in Figure 5 12 Power on the NI ELVIS II system and the prototyping board Run the application and visualize the values see Figure 5 12 The resonance frequency of the system is the frequency for which the maximum amplitude is obtained 136 Lab 5 The Study of Vibration Challenge 1 Design an experiment to determine the oscillation system Indication The system created for the other experiments is created as well with the modification shown in Figure 5 14 On the elastic lamella slates with various mass values are placed in turn the first with a mass of 2 g then 4 g 6 g 8 g and 10 g Starting from Equation 67 k O 4n v 67 m and using the first slate with the mass of 2 g the following system of equations 1s obtained k 47 v m 68 k 4r v m
2. 3 4 fit TEETE We p Oe ssas Peewee lawl F Oe seswa Dewwee lew r Oe sweewe Erres lew oe jee weewe Bvewee lew r ww erso Be rir TEITE Be 7 l sa cares eevee ssf r S owe cab oo jer ow er were se lav os ras PTTTiTTiTi Lee 3 ERTE i r uel x wel ww i w ws sx eak rer J gj d i ad Ak dd daca awd kd M od addaAd LL st i Sheed ae Pee ARABA a3 e tai xt ttt ae a a ta a i ae ae a E From the Instrument Launcher the student must start the variable power supply on the left side of the picture In addition the student can launch the NI ELVIS Scope in the center of the picture and or the digital multimeter right side of the picture NI ELVISmx Instrument Launcher DMM Scope FGEN 10 igIn DigOut Imped 2 Wire 3 Wire Basic Settings Advanced Settings Channel 0 Settings E Si Scale vertical Scale Volts Div Position Div Volts Div J QQ Q 2y g iv E oF Measurement Settings ve vs oe oe 3 Joma gt Type Slope Immediate v a Jack Connections Source fy uto Level V DMM ih g gt com Banana Device Tan Control Device Acquisition Mode device meal AE Acquisition Mode Kefi NI ELVIS II Run Continuously v evi VIS Dev1 NI ELVIS II Run Continuously v F
3. av MANE EEE EEEL EE ee ees R Figure 6 17 The circuit of the PWM control application in Multisim The PID output will act upon the duty cycle of the square wave The output of the NI Function Generator will command the MOSFET The MOSFET is completely open when a voltage larger than 5 V 1s applied on its gate terminal In order to verify the system s functionality the following steps must be taken 1 Build the testing circuit shown in Figure 6 17 Figure 6 18 and Figure 6 19 2 Start the NI LabVIEW 2010 software and modify the first application as shown in Figure 6 20 a Replace the NI ELVISmx Variable Power Supply express VI with NI ELVISm lt x Function Generator express VI from Function Measurement I O NI ELVISmx b Create constants for the Frequency Offset and Amplitude terminals Set the frequency value at 1000 Hz the offset value at 3 5 V and the amplitude value at 3 5 V In this manner the generated pulses will be only positive and the amplitude will be equal to 7 V the MOSFET will be open c Connect the PID Autotuning VI output to the duty cycle terminal of the NI ELVISm x Function Generator express VI 158 Lab 6 Introduction to Control 3 Run the application and set the PID coefficients to proper values using the autotuning methods described in the first exercise in this chapter Figure 6 18 The 3D schema of the PWM control applic
4. gt b Data Communication CED NEFGER NibCFur Connectivity i E gt ee Control Design amp Simulation PMintsDIO i SignalExpress 1 Agh ie Express Yea NI ELVISmx a Bee s ge oe cs Addons gt Favorites gt ea User Libraries gt Select a VI FPGA Interface gt RF Communications gt a Figure 1 57 The LabVIEW NI ELVIS express VIs Background The voltage divider 1s a circuit that allows users to divide the input voltage into two parts Figure 1 58 According to Kirchhoff s second law the output voltage V across R is as follows Vec V _ V 10 V Vcc V 11 Equation 11 shows that the output voltage is a fraction of the input voltage Using Ohm s law we can find the expression of the output voltage 7 Vcc RR 12 V L R But J l because they are the same current the current over the circuit In this situation we obtain Leo 13 R RK R 44 Lab 1 Introduction R V 2 Vec 14 R R Building the application d First connect the NI ELVIS II workstation to your computer using the supplied USB cable The box USB end goes to the NI ELVIS II workstation and the rectangular USB end goes to the computer Turn on your computer and power up NI ELVIS II switch on the back of workstation The USB ACTIVE orange LED turns ON In a moment the ACTIVATE LED turns OFF and the USB READY orange LED turns ON On yo
5. LabVIEW 2010 66 Lab 3 Interfacing Basic Sensors NI ELVIS II platform and NI ELVIS drivers TSL230R light to frequency converter from Parallax Inc Memsic 2125 dual axis accelerometer from Parallax Inc Mobile prototyping board Protractor Two 220 Q resistors Background In the manufacturing process automation control etc it is necessary to replace the human senses with systems that serve as extensions to the human senses These systems are called sensors The sensors allow us to be in direct contact with a phenomenon and to perceive its evolution Generally the main role of a sensor is to convert a stimulus physical chemical etc into an electrical signal that can be measured by electronic equipment Sensors can be classified according to their stimulus domains There are six such domains S Soloman 1998 Radiant signal domain Mechanical signal domain Thermal signal domain Electrical signal domain Magnetic signal domain Chemical signal domain Further classification can be made based on whether the sensor uses an additional external energy source According to this criterion there are two kinds of sensors passive and active The passive sensors do not require any additional energy source These sensors transform the input signal stimulus directly into the electrical output signal e g thermocouple photocell On the other hand the active sensors need an external energy
6. One transistor BC 177 NPN One transistor BC 107 PNP Two resistances of 100 kQOne resistance of 1 mQ One resistance of 1 kQ One resistance of 2 kQ Lab 4 Interfacing Actuators 9 One resistance of 10 KQ One resistance of 5 19 Q 5 W Component requirements for stepper motor testing include the following One stepper motor from INEX Innovative Experiment of 12 V 100 Q 7 5 degree step One integral circuit ULN 2003 which has 7 NPN Darlington pairs Four LEDs Polarized resistors of 1 kQ 92 Lab 4 Interfacing Actuators Background Relays Relays are generally used in electronic circuits The purpose of using the relays 1s to close or open a series of circuits This is performed by activating the mobile armature of the relay Electromagnetic relays and electronic relays are among the most widely used Electromagnetic relays will be presented subsequently An electromagnetic relay used in electronic circuits usually consists of three main components the electromagnet the electric contacts and the armature In Figure 4 3 a classical electromagnetic relay is presented The components of the relay include a fixed armature 1 a mobile armature manufactured from steel 2 a coil 3 and a resort 4 The functioning principle is the following at the passing of an current through the coil the mobile armature 1s attracted and will close the contact C when the current reaches the value This value
7. Using the Contact Voltage and Contact Current values the Contact Resistance values can be calculated using Equation 25 Power on the NI ELVIS II system and the prototyping board Run the application and visualize the values 100 Lab 4 Interfacing Actuators Figure 4 8 Panel and Diagram of the Contact Resistance application Lab 4 Interfacing Actuators 101 Exercise 4 2 Monitoring the voltage in the coil For very many industrial applications it is important to know the opening voltage and the closing voltage of the relay The following experiment determines the two voltages The experimental setup used to determine the voltages is the one in Figure 4 6 Because the relay behaves as an LED on a complete cycle meaning it has a hysteresis for the monitoring of the voltage one of the many facilities of the NI ELVIS is used namely the 2 channel oscilloscope relay I 2 3 9 Build on the prototyping board of NI ELVIS the setup shown in Figure 4 6 Start the LabVIEW software Build the application that has the Panel and the Diagram shown in Figure 4 9 Place in the diagram the NI ELVISmx Digital Writer express VI to realize the control of the system Place in the Diagram the NI ELVISmx Variable Power Supplies express VI The excitation of the relay coil is realized using an icon for the triangular signal generation that varies from 0 V to 12 V with a frequency of 1 Hz and the phase of 90 see t
8. leda Temperature Actual Temp A controller type 80 0 a a l PID gains relay cycles f Oan m L proportional gain Kc 9 20 965092 i v 60 0 relay amplitude 2 integral time Ti min 9 0 804362 Joso 5 m 40 0 t derivative time Td min 9 0 160872 ee E z nomai yf PV noise level B output range J sas 15 0 m 000456 f output high reen a Time E Bi 9 100 00 Temperature C PID Output Plot 0 WW output low 80 110 ooo E 8 0 Set Point C 60 i a 6 0 35 40 4 50 0 n J Te 4 0 i x gt e 25 95 40 20 e 60 as 0 0 a i z gt 00 00 13 00 17 16 10 70 15 Time 5 75 0 80 50 000 set Point Overrange Time Interval J 50 49 986 Actual Temp In Range f 4 1 Figure 6 23 The Panel of the temperature control 162 Lab 6 Introduction to Control 3 PID Control Temperature vi Block Diagram a fos File Edit View Project Operate Tools Window Help gt E on les bal fof 15pt Application Font od EAE stop i Device Name fe i Temperature Set Point C Temperature A autotuning Temperature C Fam Fter eT ore output rang i PID Output PID Autotuning vi PID Control Input Filter vi z gt rature vi ap BS ham ma ar pire j 100 a EE vise PID gains f i H ba ai ies O op Celsius Y m i i emperature H E gt error out k mi S 4 NI ELVISmx by status Time Interval autotune F GE 3 FA ae Variab
9. Configuration Instrument Control Device DC Voltage Mode Auto Null Offset Y Run Once E LabVIEW Measurement Settings Measurement Function Banana Jack Connections DMM V COM a 7 gt i 2 Hide Help Back El A Digital Multimeter Controls the basic digital multimeter DMM capabilities of the NI ELVIS II All functions are autoranging You can set certain DMM functions to specific ranges The DMM has the following features DC or AC voltmeter e DC or AC ammeter e Ohmmeter e Capacitance meter Tadiuintanan makar Banana F Jack Protoboarc Connections Demonstrates how the device under test DUT should be 4 m p oK Cance Figure 1 60 The DMM SFPPower up the prototyping board Press the Run button and notice the measured voltage f Create the Scale select control Right click on the Scale select input of the Temperature subVI and select the Create Control option g Activate the Panel window of the VI h Run the VI and see the measured temperature Put your hand on the temperature sensor and notice the variation 1 Select another temperature scale from the Scale select control and see the values j Press the STOP button Save the VI as Real Temperature Monitoring 48 Lab 1 Introduction 3 Real Temperature Monitoring vi Front Panel File Edit View Project Operate Tools Window Help a n 3 Real Tem
10. optimum values The method with the lowest performance is the manual method This method attempts to find the PID coefficients without using any math rules trial and error It 1s an online method and requires experienced personnel The first non manual method for PID tuning was proposed by Ziegler and Nichols in 1942 Two variants of the Ziegler and Nichols method are widely used the process reaction method and the ultimate cycle method The process reaction method This method is based on the system s reaction in an open loop when a test signal is applied The test signal is a step signal The step size OP can be as large as possible but without endangering the process The system s response 1s plotted on a graph The resulting graph is called a process reaction curve Figure 6 7 This curve can be described through effective lag or dead time represented as L and the 146 Lab 6 Introduction to Control time constant 7 The dead time Z represents the time elapsed from the moment when the signal test was applied and a noticeable modification in the process output is observed The time constant T is the time interval between t and t2 where t 1s the time coordinate of the intersection point A of the tangent drawn through the inflection point of the curve with the time axis and tz is the time coordinate of the intersection point B of the tangent with the final value line OP see Figure 6 7 process reaction curve point o
11. Addons i je Ja User Controls gt fking Select a Control RF Communications b Figure 1 39 The selection of the Enum control g Edit the Enum control following the steps listed here a Right click on the Enum control b Select the Edit Items option and introduce the items name in the Items field using the Insert button Figure 1 40 The used names are Kelvin Celsius and Fahrenheit c Press the OK button 43 Enum Properties Scale select Eal Appearance Data Type l Display Format Edit Items Documentation ajo Items Digital Displa A Insert rein o Celsius Delete J Fahrenheit ns Move Down OK Cancel l Help Figure 1 40 The items editing of the Enum control h Arrange the panel of the VI as in Figure 1 41 1 Lab 1 Introduction 33 43 Untitled 2 Front Panel m File Edit View Project Operate Tools Window Help TE i set Apekaton en iE Voltage Temperature Scale ry m BE i Scale select Kelvin Figure 1 41 The panel for the temperature application Activate the Diagram window Select the Case Structure from Express Execution Control and make it a convenient size by pressing and holding the left mouse button and dragging the mouse to the desired size Wire the Scale select icon with the Case selector l Notice that the selector from the top of the case structure has changed and contains the Kelvin and Celsius options pres
12. G Parameters J to f b f f x initial parameters ry Ho flo 23 ON 1E 7 20 0 0015 File Edit View Project Operate Tools Window Help B18 OB hele nr Figure 7 20 The Panel and Diagram for Levenberg Marquardt fitting 192 Lab 7 The Photovoltaic Characterization Notes
13. Goal This lab is designed to enhance the understanding of the control system concept The PID algorithm is used to create the control system This algorithm is applied to control the speed of a DC motor and the temperature of a heater Required Components Components requirements and software applications are as follows LabVIEW 2010 NI ELVIS II platform and NI ELVIS II drivers NI LabVIEW PID and Fuzzy Logic Toolkit DC motor Tachometer IRF530 MOSFET transistor 1N4007 semiconductor diode M335 temperature sensor 27 Q 5 kQ and 5 6 kQ resistors Lab 6 Introduction to Control 141 Background Introduction Automation of the manufacturing process requires control of all of the involved machines and processes Components of such a control system include an input an error signal representing the difference between the desired values known as the SP or set point and the feedback signal and an output that provides a signal to modify the system The simplest control system algorithm is the on off algorithm If there is an error signal at the control system input the correcting device is switched on and when the error signal ceases the correcting device is switched off The performance capabilities of such a system are limited It is used only for control systems where the precision doesn t have to be very accurate PID Controller A more advanced algorithm for control is the PID algorithm It 1s k
14. SignalExpress ii C i vfi Express Comparison zi i gt te a C gt S i g Era ms a foal Fe je 5 EN Addons i oo Synchronizat Favorites 4 User Libraries E Select a VI FPGA Interface I RF Communications gt i i I lt o N E a r oO Figure 1 53 The For loop structure a The path for the structure palette b The drawing of the For loop c The form of the For loop j Move the Temperature indicator inside of the For loop using the Editing positioning and resizing tool Make all the connections as shown in Figure 1 54 using the Connecting tool Notice that the wire between the Scale indicator and the For loop tunnel is broken This happens because the For loop is an indexed loop This means that the tunnel output is of array type i it memorizes all data that arrives at the tunnel during execution time To fix this problem right click on the tunnel and select the Disable Indexing option from the opened pull down menu Figure 1 55 No of Measurements Figure 1 54 The Diagram of the finite temperature measurements Scale i be st b Disable Indexing Replace with Shift Register String Palette d Array Palette Create d Properties Figure 1 55 Disabling the Indexing of the For loop structure Lab 1 Introduction 41 k Return to the Panel window and set No of Measurements to 20 Run the application and see the results l Save the VI as Finite Temperature Measurements vi and
15. So for calculation of the temperature from the measured voltage use the following equation t K U V 100 15 a Power down the prototyping board Change the R2 resistor with an LM335 as shown in Figure 1 59 b Start the DMM SFP and press the Run button Notice the measured voltage Multiply by 100 manually The resulting value is temperature in the Kelvin scale Use Equations 8 and 9 to obtain the temperature in the Celsius and Fahrenheit scales c Put your hand on the temperature sensor and notice the modification of the temperature 46 Lab 1 Introduction XLV1 R1 5 6kQ o DMM VQ gt o DMM COM Figure 1 59 The LM335 temperature measurement circuit Build a thermometer using the DMM express VI in LabVIEW Start the LabVIEW software Open the Temperature Monitoring vi Modify the Diagram by following these steps l 2 a Navigate to Measurement I O NI ELVISm x and select the NI ELVISmx Digital Multimeter express VI Place it inside of the While Loop The SFP will open Figure 1 60 Delete the Voltage Read subVI and the connection wire between this subVI and the Temperature subVI Stop the DMM by pressing the Stop button Press the OK button and wait until the compilation of the VI 1s done Connect the Measurement output of the digital multimeter with the voltage input of the Temperature subVI Figure 1 61 Lab 1 Introduction 47 G NI ELVISmx 9 Eje Run
16. and run the VI j Press the STOP control and notice what happens k Save the VI with the name Temperature Monitoring vi and close it 42 Lab 1 Introduction Exercise 1 4 Introduction to the NI ELVIS Il workstation The NI ELVIS II platform includes a suite of 12 virtual instruments in a compact form ideal for hands on learning By combining the NI ELVIS workstation with different boards and LabVIEW applications the resulting platforms can be used for different disciplines including Circuit design Control design simulation and mechatronics Digital electronics Microcontroller embedded systems Telecommunications Renewable energy The NI ELVIS II workstation can be used with its own standalone software suite the NI ELVIS Soft Front Panels SFP Figure 1 56 or it can be programmed from LabVIEW using the NI ELVIS express VIs Figure 1 57 Programming the NI ELVIS II platform Exercise Implement a voltage divider using the NI ELVIS II and the NI ELVIS SFP and then build a digital thermometer using an LM335 sensor Y NIELVSm Instrument Launcher EaARA DMM Scope FGEN VPS Jode DSA ARB Digin DigOut Figure 1 56 The 12 virtual instruments Lab 1 Introduction 43 Functions Q Search Programming r Measurement I O gt Instrument I O Measurement I O NI ELVISmx Vision and Motion i mnx mxBas b Mathematics l g an Signal Processing 1 gt
17. 2 UIV ol 100 2 2 76 Using the Wait Until Next ms Multiple VI the time interval for iterations can be set Create a property node for Speed chart Right click on the Speed chart icon on Diagram and chose the option Create Property Node X Scale Offset and Multiplier Multiplier and connect it with dt PID VI output This feature allows scaling of the Speed chart depending on the iteration time In the panel place a Knob control call it Set Point RPM add a Gauge indicator and call it Actual Speed Right click on the Actual Speed indicator and choose the Add Needle option This will allow visualizing of the Process 18 19 20 2i Lab 6 Introduction to Control 153 Variable PV and the Set Points SP values on the same indicator In order to visualize the digital values right click on both and choose the Visible Items Digital Display option Choose the right device name for NI ELVIS I on the Device Name control as well as the values for K T and Tz coefficients Run the application and see the reaction of the system If the system is unstable try to apply the Ziegler and Nichols tuning methods to find the best PID coefficients Modify the application as in Figure 6 12 and Figure 6 13 Replace the PID VI with PID Autotuning VI Create the autotuning parameters and autotune F controls for the PID Autotuning VI Create a local variable for the PID Gains control Right click on the PID Gains control i
18. 2 aa where v is the oscillation frequency of the system without the mass applied and v is the oscillation frequency of the system with the slate of 2 g applied on the elastic lamella Figure 5 14 Configuration to determine the oscillation system mass where a represents the slates Lab 5 The Study of Vibration 137 The mass of the oscillation system is determined by solving Equation system 68 where v and v are determined by measurements see Equation 69 which follows oe 2v n yw 69 Several determinations will be made using the other masses attached to the elastic lamella in order to obtain a real value of the oscillation system mass The mass of the system will be determined in this case as a mean of the masses found 2 Determine the elastic constant of the lamella 138 Lab 5 The Study of Vibration Notes Lab 6 Introduction to Control 139 Lab 6 Introduction to Control Instructor s Notes In order to control a system it is necessary to manage command or regulate the response of the system This can be achieved with a device or a set of devices The control can be done in an open loop or in a closed loop system Figure 6 1 Desired Ideal value system a b Figure 6 1 Types of control systems a The open loop control system b The closed loop control system To illustrate the concepts of open loop and closed loop systems consider the following examples If a man stands
19. A number of cells can be bound in parallel and then in series the effect obtained in this case being a combination of the two By these methods of binding the solar cells in series and in parallel the solar panels are obtained The typical panels are obtained by binding in series 36 or 76 cells To obtain even higher generated powers solar panels arrays are built as shown in Figure 7 6 Figure 7 6 The array system References D T Cotfas P A Cotfas S Kaplanis amp D Ursutiu 2008 Results on Series and Shunt Resistances in a c Si PV Cell Comparison Using Existing Methods and a New One Journal of Optoelectronics and Advanced Materials Vol 10 No 11 pp 3124 3130 D T Cotfas P A Cotfas D Ursutiu amp Cornel Samoila 2010 Current Voltage Characteristic Raising Techniques for Solar Cells Comparisons and Applications 2th International Conference on Optimization of Electrical and Electronic Equipment Optim 2010 M A Green 2002 Physica E Vol 14 No 11 L L Kazmerski 1997 Photovoltaics A Review of Cell and Module Technologies Renewable and Sustainable Energy Reviews Vol 1 pp 71 170 174 Lab 7 The Photovoltaic Characterization I Spanulescu 1983 Celule solare Editura Stiintifica si enciclopedica Bucharest Romania U Stutenbaeumer amp B Mesfin 1999 Equivalent Model of Monocrystalline Polycristalline and Amorphous Silicon Solar Cells Renewable Ener
20. As industry adoption of virtual instrumentation for measurement control and design grows hands on training in this area is becoming essential for every engineering and science student NI ELVIS and LabVIEW help us to incorporate 52 Lab 2 Introduction to Testing Measurement and Data Acquisition virtual instrumentation into the curriculum by providing multiple capabilities in one compact affordable system With this system we can give a unique hands on experience that will help students meet the design challenges they will face after graduation Goal Students will begin to understand how to build and use computer based instrumentation The field of data acquisition DAQ and instrumentation encompasses a very wide range of activities At its simplest level it involves reading electrical signals into a computer from some form of sensor In our case we discuss sensors or different devices that interact with NI ELVIS system Often the data have to be analyzed or processed in some way in order to generate further signals for controlling external equipment or for interfacing to other computers Required Components Component requirements and software application include LabVIEW 2010 NI ELVIS II or NI ELVIS I Application VIs DC motor Tachometer Background The National Instruments Educational Laboratory Virtual Instrumentation Suite NI ELVIS is a LabVIEW and computer based design and prototyping environment
21. Display Measurements Stop Help Run Stop Log Help pig Mcno VICHL Autoscale gt E E o gt Figure 2 7 The NI ELVIS control and measure system VPS Scope and DMM Lab 2 Introduction to Testing Measurement and Data Acquisition 63 Challenge We presented one conventional method of measuring RPM using a device called a tachometer which can precisely measure the speed of up to thousands of RPM There are specifically two types of tachometers contact and non contact tachometers The contact tachometer is physically attached to the motor shaft as in our case thereby reducing the speed and providing an inaccurate RPM reading The non contact tachometer utilizes a brightness sensor that detects rotations For instance when a motor spins with a black and white disc attached to the shaft the tachometer flashes the rotating disc with an LED and can see the varying light reflection from light to dark through its brightness sensor A chip measures the time for a light to dark to light progression and thus the RPM speed Students can modify the laboratory exercise and make a new project to build a non contact tachometer It 1s important to be able to interpret the speed of a DC motor besides using RPM units because as you learn more about electronic technology you will likely come across a different unit of speed for the DC motor The internationally accepted metri
22. Indicator place it on the Panel and call it Temperature In the same manner create the Scale indicator from Express Text Indicators String Indicator Arrange the controls and indicators on the Panel using the Aligning Distributing and Resizing Objects buttons Figure 1 12 in the desired positions Activate the Diagram window Select the For loop structure from the extended Functions palette following the path Programming Structures Figure 1 53a The mouse pointer becomes Ma Click and drag to create a For loop of the desired size as shown in Figure 1 53b Choose the Select VI option from the function palette A file explorer window will open Find the path to the first VI created in this example Voltage Read VI and select it Place it inside the For loop Repeat the previous step this time selecting the Temperature VI and placing it inside the For loop Connect the Voltage output of the Voltage Read subVI with the Voltage input of the Temperature subVI 40 Lab 1 Introduction Functions a Search gt Programming Measurement I O Instrument I O Programming Structures Gall k mrt a Cs 1 Structures ji G Structures For Loop Signal Processing i i i i Data Communication i a 3 B i i i Vision and Motion Mathematics El Connectivity Numeric T fe ee S Control Design amp Simulation gt RE i i IN
23. Source Frequency Hz Amplitude Vpp re 35 3 as 2 8 1 9 0 10 yp a e Immediate we Positive x Device Name Dev4 F Detected frequencie 20 8616 Level V m 133 1 1 1 I 1 1 I I 1 1 1 I 1 1 1 1 1 1 50 0m 100 0m 150 0m 200 0m 250 0m 300 0m 350 0m 400 0m 450 0m 500 0m 550 0m 600 0m 650 0m 700 0m 750 0m 800 0m 850 0m 900 0m 950 0m 1 0 4 w r Figure 5 9 The Forced Vibrations Panel File Edit View Project Operate Tools Window Help gt gt a n V 85 bal 15pt Application Font Ror i Se Device Name 3 y oer Detected amplitude a gt Device Name a I gt CHO Enable doe Vibration error in Frequency Hz a Amplitude Vpp e SignatRovte ep a erioa d 5 a Fe fi A gt errorin i d i p e i error out Fs error out gt A i Fs i Figure 5 10 The Forced Vibrations Diagram The resonance phenomenon The application can be modified as in Figure 5 12 and Figure 5 13 in order to find the resonance curve The application permits the induction on a lamella of a force of variable frequency contained within the domain Start Frequency and Stop Frequency 1 Remove Case Structure Update FG button and Frequency control 134 Lab 5 The Study of Vibration 2 Create two new controls and call them Start Frequency Hz and Stop Frequency Hz 3 Set the fre
24. Toliyat amp G B Kliman 2004 Handbook of Electric Motors New York ISBN 0824741056 M Zupan M F Ashby amp N A Fleck 2002 Actuator Classification and Selection The Development of a Database Advanced Engineering Materials 04 No 12 Lab 4 Interfacing Actuators 97 Exercise 4 1 Determination of the contact resistance of the relay Because every conductor has a resistance a voltage drop appears on this resistance leading to a decrease in consumer performance Relays are sometimes presented in scientific literature as ideal devices of commutation which is with resistance at zero contact and only one transition of commutation In practical use however the contacts of the relays have a contact resistance different from zero and this rises in time with repeated commutations The contact resistance is typically situated within an interval from 50 mQ to 200 mQ The purpose of this experiment is to measure the contact resistance of the relays For some practical applications it 1s necessary to know exactly the value of this resistance as it 1s added to the charge resistance Moreover another reason for measuring the contact resistance is the fact that with the aging of the relay this resistance changes due to phenomena that appear at the closing and opening of the contacts To practically realize the experiment it has to be performed on the prototyping board of the NI ELVIS as shown in Figure 4 6 The
25. are methods both in dynamic and in static regimes Most methods are realized in the static regime and under illumination Within this experiment the two characteristics method will be presented The influence of the series resistance upon the I V characteristic of the cell and at the same time upon its efficiency is presented in Figure 7 12 With the raising of the series resistance of the solar cell a translation towards the left of the characteristic is to be observed leading to a dropping of the fill factor The excess raising of the series resistance can lead to transforming the solar cell from a current generator into a consumer 0 350 x 0 300 0 250 w 0 200 os 0 150 0 100 0 050 0 0 0 100 0 200 0 300 0 400 0 500 Voltage Y Figure 7 12 The series resistance influence on the l V characteristic of the solar cell The two characteristics method is a method that uses two I V characteristics raised at the same temperature for two illumination levels The two characteristics are translated one from the other with the quantities AIlsc and AIscRs AV1 Figure 7 13 on the directions y and x Two corresponding points from the characteristics are moved away from each other at a distance equaling the translations of the coordinates system The series resistance will be thus determined from the ratio in Equation 87 87 To obtain Equation 87 the starting point is given by the equations for the sin
26. close it The monitoring temperature VI Modify the Finite Temperature Measurements vi using the following steps Open the Finite Temperature Measurements vi b Replace the Waveform Graph with a Waveform Chart Right click on the Waveform Graph indicator and navigate to Replace Express Graph and select the Waveform Chart indicator c Adda numeric control and call it Delay d In the Diagram replace the For loop with the While loop Right click on the For loop border and select the Replace with While Loop option from the pop up menu e Delete the wires between Scale Temperature measurements and Temperature subVI Using the Editing positioning and resizing tool select the desired wire click double click or triple click and press the DEL key Move the Scale and Temperature measurements indicators inside of the While Loop and renew the connections f Delete the No of Measurements control Click on it and press the DEL key g Create the STOP button to stop the While loop Right click on the Loop condition Ch and choose the Create Control option from the pop up menu h Select the Time Delay function from the Express Execution Control palette and place it inside of the While Loop Select the Time Delay seconds value and press the OK button Move the Delay control inside of the While Loop and connect it with the Delay Time s input of the Time Delay icon i Return to the Panel window and select a value for Delay ex 1
27. factor is related to the curvature of the I V characteristic P FF 2 84 Vo x Lz l l The cell efficiency can be determined from these three external parameters and from the area of the cell see Equation 85 These parameters can be determined through direct measurements as well as by subtraction from the I V characteristic Vee VXL XEF a ee 85 P incident solar power The shunt resistance and the series resistance are two of the internal parameters also called parasite resistances The latter is determined by the series resistance of the base by the resistance of the metal semiconductor contacts of the electrodes and by the resistance of the diffused layer from the illuminated surface of the cell The other internal parameters are the reverse saturation current the ideality factor of the diode and the photo generated current Many methods can be used to determine the parameters of the solar cells The measurements can be performed in the lab as well as in natural light conditions When the measurements are performed in the lab the parameters can be determined both in illuminated conditions and in the dark To be able to create the mathematical model that describes the behavior of the solar cell 1ts equivalent circuit has to be used In Figure 7 3 the equivalent circuits of the silicon solar cell are presented from the simplest to the most complex The equations that mathematically describe the phenomena that take place within
28. measurements This indicator can be found in the Express Graph Indicators controls palette Figure 1 51 Controls Q Search b Express 4 sh pa ri mei T gt gt _ gt w 0 i i fa Graph Indicators User Controls Waveform Chart Select a Control F F I i RF Communications Chart Graph XY Graph Figure 1 51 The Graph Indicators palette Building the temperature measurement VIs This VI will execute a finite number of temperature measurements a Open a Blank VI and build the Panel in Figure 1 52 Lab 1 Introduction 39 43 Finite Temperature Measurements vi Front Panel o elea File Edit View Project Operate Tools Window Help gt A TT 15pt Application Font No of Measurements Temperature measurements Plot 0 IM Temperature Aio 320 Jo 4 a 1 1 1 1 1 1 1 1 1 Does A ber BS No of measurements Figure 1 52 The finite temperature measurements Select the Numeric Control from the Express Numeric Controls palette place it on the Panel and call it No of Measurements Right click on this control and from the opened pull down menu select Representation Long Id option wal This option changes the control into an integer numeric control Select the Waveform Graph from the Express Graph Indicators palette place it on the Panel and call it Temperature measurements From the Express Numeric Indicators palette select the Numeric
29. of the current is compulsory for defeating the force exerted by the resort and is called the threshold value If we make a comparison with the actuators it is clearly seen that the output value at relays abruptly varies when the threshold value of the current is reached while for actuators the variation is continuous being a function of the input value To avoid damaging or aging the contacts the current that passes through them needs to be limited A capacitor of 0 1 uF in series with a resistor of approximately 100 Q can be used to provide a supplementary protection of the contacts These components are used in order to eliminate instantaneous variations of the current in the commutation regime of the relay For the relay contacts several materials are used specifically Ag which presents a low contact resistance is relatively cheap and has very good thermal and electrical conductivity making it the most widely used material the AgCu alloy with a good resistance to wear but with a high contact resistance AgW which has a high contact resistance and demonstrates a low resistance to corrosion and the AgCdO alloy which demonstrates a higher resistance to melting and has properties of extinction of the electric arc Lab 4 Interfacing Actuators 93 Figure 4 3 The constructive schemata of an electromagnetic relay The electromechanical relays can be normally opened relays Figure 4 4 a normally closed relays Figure 4 4 b or dual
30. of the series resistance for one solar cell A major advantage of the educational platform NI ELVIS can be observed here namely with only a few parts and medium level programming knowledge extremely attractive experiments can be created for students 188 Lab 7 The Photovoltaic Characterization gadagan ee Saag Comparasion of the I V C File Edit View Project Operate Tools Window Help Solar Cell I V I Series Solar Cell LV Paralel Solar Cell I V D Users pcotfas Documents LabVIEW Data Carac Celula 99 been D Users pcotfas Documents lt LabVIEW Data Carac Panou Serie 11 Ehan D Users pcotfas Documents LabVIEW Data Carac Panou Paralel 11 Ehan Current A Read From Measurement Read From Measurement File k peed P ii Read From Measurement File3 Figure 7 17 Panel and Diagram of the series resistance application Lab 7 The Photovoltaic Characterization 189 File Edit View Project Operate Tools Window Help gt E an 35et Application Font L o i 6 Filename D Users pcotfas Documents LabVIEW Data Carac Panou Serie TN E han Filename 2 D Users pcotfas Documents LabVIEW Data Carac Panou Serie 11 E hana 7 D Users pcotfas Documents f LabVIEW Data Carac Panou Paralel TN E han j Filename 2 D Users pcotfas Documents LabVIEW Data Carac Panou Paralel 11 E hann Figure 7 18 The series resistance compa
31. s Setting text features for objects Figure 1 12 Aligning distributing resizing and reordering objects References P A Cotfas 2010 Prelucrarea semnalelor Aplicatii in LabVIEW Editura Lux Libris Brasov Romania N Kehtarnavaz amp N Kim 2005 Digital Signal Processing System Level Design Using LabVIEW Elsevier Newnes Oxford UK D Ursutiu 2001 Initiere in LabVIEW Programarea grafic in fizic 1 electronic Editura Lux Libris Brasov Romania NI LabVIEW Technical Resources http www ni com labview technical resources 2010 LabVIEW User Manual National Instruments Austin TX 14 Lab 1 Introduction Exercise 1 1 Create your first Virtual Instrument in LabVIEW This example will introduce you to graphical programming The goal is to show how easy is to program in LabVIEW We will use simple arithmetical operations to solve a first degree equation Background A first degree equation is also known as a linear equation The form of the first degree equation is given by Equation 1 a x b 0 1 where a and b are the coefficients of the equation and x is the equation s unknown To find the solution to this equation rewrite Equation 1 in the following form 2 a 2 xX The uniform rectilinear motion equation is a good example of an application that requires solving a first degree equation X Vol Xo 3 where x is the actual position of the material point vg is
32. source for their normal functionality The additional external energy is modified depending on the stimulus to produce the electrical output signal Sensors can also be classified into absolute and relative sensors If the response of the sensors doesn t need any other references the sensors are absolute ones if the response of the sensors is dependent on the external references e g atmospheric Lab 3 Interfacing Basic Sensors 67 pressure for pressure sensors environmental temperature for thermocouples etc the sensors are relative ones Light Sensors Light measuring and monitoring are very important for a large number of domains From public lighting to optical fiber communication many industries use light sensors Light sensors include photoresistors photodiodes phototransistors and solar cells among others In this lab we will test a light sensor TSL230R which is slightly different from other sensors because it converts light intensity into frequency The TSL230R Light Sensor The TSL230R light sensor is used for light intensity measurement and is produced by Texas Advanced Optoelectronic Solutions Inc TAOS This sensor measures the light intensity that falls on its surface using an array of silicon photodiodes The measured value of light intensity is converted into a square wave using a current to frequency converter The frequency of the output wave is proportional to the measured value The photodiodes and th
33. the initial velocity t is the actual time we considered the initial time to be equal to zero and x is the initial position of the material point If we want to know the necessary time t during which the material point moves in the x position we can write X Vol X gt vh X xX 0 gt at b 0 4 where a v and b xo x Solving Equation 4 gives the desired time Building the LabVIEW VI From the start panel of the LabVIEW application Figure 1 4 select the Blank VI option This option will open two windows the Panel and Diagram windows as shown in Figure 1 5 This is an empty application and is called Untitled vi Lab 1 Introduction 15 For the purpose of better understanding how LabVIEW programming is done it is recommended to arrange both windows in the tile left and right format as in Figure 1 13 This option can be selected from the pull down menu Window Tile Left and Right or by pressing the CTRL T keys bE dh Untitled 1 Block Diagram m File Eat View Project Operate Tools UE Hep Fle Edt View Projet Operate Tools Window Help BASM s5et Applicaton Fe Show i omele i Show Project Figure 1 13 The Panel and Diagram windows distributed in the tile left and right format Build your Panel as shown in Figure 1 14 Notice what happened in the Diagram coe mes Figure 1 14 Building the Panel and Diagram for solving a first degree equation For building this Panel follo
34. the output as voltage the sensitivity is given in mV g Notice For good results in measurements the mass of the accelerometers should be significantly smaller than the mass of the system to be monitored Memsic 2125 Accelerometer The Memsic 2125 Mx2125 is a dual axis low cost thermal accelerometer with a dynamic range of 3 g This sensor is provided by Memsic as a surface mount product and Parallax mounts it on a PCB providing all I O connections in 6 pin DIP package format Figure 3 5 Lab 3 Interfacing Basic Sensors 71 w Tilt Figure 3 5 Memsic 2125 dual axis accelerometer Memsic 2125 Operation The Mx2125 contains a gas chamber with a centered heater and four temperature sensors distributed on each chamber wall The operation mode of the device is based on heat transfer by natural convection When the accelerometer is in the horizontal position the heated gas rises to the top center of the chamber and the temperature gradient is symmetrical therefore the sensors will measure the same temperature When the accelerometer is tilted the temperature profile is disturbed and the temperature gradient will be asymmetrical By measuring the temperature difference between sensors the acceleration can be detected The temperature difference between the two pairs of sensors is converted into an output pulse signal for the two axes Figure 3 6 T1 I Ld lt gt T2 Figure 3 6 The Memsic 2125 output signal Th
35. the sampling frequency is equal to or less than twice the frequency of the input signal a signal of lower frequency 1s generated from such a process this is called aliasing In the following virtual instrument Nyquist_Aliasing vi Figure 2 4 an example of sampling is shown Students can study and verify the following concepts using the Nyquist Aliasing v1 Nyquist theorem Sampling rate s gt 2 highest frequency component of interest in the measured signal Nyquist frequency the highest frequency component allowed to avoid aliasing for a given sampling frequency Effects of various sampling rates when sampling a sine wave of frequency f If a signal is sampled at a sampling rate smaller than twice the Nyquist frequency false lower frequency component s appear in the sampled data spectrum This phenomenon is called aliasing 60 Lab 2 Introduction to Testing Measurement and Data Acquisition Nyquist_Aliasing vi Front Panel DER File Edit Yiew Project Operate Tools Window Help gt on 13pt Application Font tor Tar a Waveform Graph Signal Frequency iw SPECTRUM Aliasing AN SA 1 i 1 1 1 1 1 1 1 1 i O25 5 75 1012 5 1517 52022 5 2527 530 Frequency Hz gt Nyquist_Aliasing vi Block Diagram File Edit View Project Operate Tools Window Help Sm E Ealo seein Foe a Ia Relative Time Y b FFT Spectrum Mag Phase vi OO
36. with his hands raised sideways holding a pencil and tries to touch his nose with the pencil tip while keeping his eyes closed this movement becomes very difficult The difficulty derives from the fact that the man doesn t know the exact location of the pencil tip This is open loop control Any change in his movement will lead to an increased chance of error because he has no feedback for correction If he opens his eyes though he will see the pencil tip and will make the necessary adjustments to correct the error This is closed loop control Another example of a control system is the furnace of a house In normal conditions if the system works at x of its capacity the temperature in the house will be y C If it s necessary to increase the temperature to y2 C then the furnace must work at x2 of its capacity When a disturbing factor appears such as a window opening the system will not react because there is no mechanism for feedback In order to close the loop a temperature sensor should be used to control 140 Lab 6 Introduction to Control the furnace The temperature sensor will ensure that any change in the house temperature will be noticed and then the furnace would be controlled accordingly Widely used control algorithms include PID algorithms fuzzy logic algorithms neural networks algorithms and others The most frequently used algorithm is the proportional integral differential or three terms the PID algorithm
37. 25 45 ih 5 35 55 3535 6 Time Detected frequency Relaxation time s 20 5649 0 726484 Logarithmic decrement 0 033467 Damping coefficient 0 688246 rations vl vi Block Diagram Lojas File Edit View Project Operate Tools Window Help S O Ge baler ot Set Arvesion Font EA Detected frequency Extract Single Tone Information vi ae vc j T ps IDE Devic b 3 Damping coefficient NIELVISmx 2 THY Oscilloscope f iM Device Name igger CHOEnable b Channeld 4 Trigger i ror i Mean vi ion ti a gt Relaxation time s gt e Logarithmic decrement a m error in Stop l g Horizontal ELVIS Channel 0 gt H Figure 5 7 The Damping Vibrations Diagram 3 Place in the Diagram the NI ELVISmx Variable Power Supplay express VI from Function Measurement I O NI ELVISmx Right click on the Device Name input and choose the Create Control option Repeat the operation for the Supply V input create a constant and choose the 3 V value maximum 3 6 V so as not to damage the accelerometer Also create a constant for error in input 4 Next add in the Diagram the NI ELVISmx Oscilloscope express VI from Function Measurement I O NI ELVISm x In the configuration window 10 Il Lab 5 The Study of Vibration 127 choose for Channel 0 Source option AI0 Connect the Device Name input to the Device Name control
38. 5 The Study of Vibration 123 Because in the solutions of the attached equation we have free radicals we must discuss the quantity 6 w Three cases can be distinguished Case I If gt w high damping the quantity below the radical is positive and the solutions in Equation 43 are real and distinct Equation 44 the equation of the elongation can be written as X etl ae tO E 45 The initial conditions are used in practical applications in order to determine the integrating constants C and C2 The motion described by Equation 45 is a nonperiodic motion The motion trajectory is represented in Figure 5 3 0 20 017 0 15 012 p10 0 08 0 05 003 S S S S S E a a E 00 05 10 15 20 25 30 35 40 45 50 55 60 t Figure 5 3 Trajectory of nonperiodic motion for 6 gt Case II If the quantity below the radical equals zero and there will be two real and equal solutions for Equation 42 In this case the solution for the elongation is written as follows Xft C a C t e 46 In this case too there is a nonperiodic motion The elongation asymptotically tends towards zero so that the body moves towards the equilibrium position in minimum time without oscillating The motion is in this case called critical nonperiodic motion Case III If lt w low damping the quantity below the radical is negative and the solutions to the characteristic equation are complex In this case the e
39. 5 The Study of Vibration 129 Exercise 5 2 Study of forced harmonic oscillatory motion In many practical situations the use of vibrations is helpful for example the selection of certain materials looms vibration testing for machines and aluminum artificial aging As in the real case the oscillatory motion is a damped motion to be able to use the vibrations benefits they have to be forced In order to maintain the vibrations external forces need to be applied perturbing For the practical applications it is interesting to have a look at the case when the external force Fe being applied is a force of periodic type see Equation 51 which follows Rao et al Thomson F F sm t 51 The equation describing the motion in case of perturbing force application Fe 1s mx px kx F sin t 52 Equation 52 can be written as x 26x x qsin t 53 where 6 and o are previously defined constants and q F m Equation 53 is a nonhomogenous second degree differential equation with constant coefficients The solution of the nonhomogenous equation is given by the sum of the homogenous equation solution x Equation 41 and a particular solution xpi X X X unde X Asin at g cu A Ae 54 1 The particular solution is built starting from the term that gives its nonhomogeneity thus a sinusoidal solution is chosen for which we must determine the constants A and A sin a t 55
40. 91 amp Min The proceedings are similar for the short circuit currents and J 2 T represents the cell temperature and with a good enough approximation the room temperature can be taken into consideration If a more precise measurement is desired a temperature sensor can be used see the previous labs The elementary charge g and the Boltzmann constant k are both constant and the values are q 1 6 10 C and k 1 32 10 J K The theoretic value of m is 1 in the case of the diffusion mechanism The real values are situated within the interval 1 2 The fitting of the I V characteristic can be performed in order to determine the cell parameters Realize an application that permits this The single diode model is used for this purpose see Figure 7 3 b For the fitting the icon Nonlinear Curve Fit Vi can be used along with the path Functions Mathematics Fitting The fitting 1s realized using the algorithm Levenberg Marquardt see Figure 7 20 The model must be introduced for the fitting the single diode model in our case and the initial fitting parameters For the cell used in Exercise 7 1 the initial parameters can be seen in Figure 7 20 By fitting it is also possible to determine the short circuit current a the reverse saturation current J b the ideality factor of the diode m c k T q and the shunt resistances R I d File Edit View Project Operate Tools Window Help e model a b exp c x 1
41. Block Diagram from the pull down menu Window Open the Functions Palette from the pull down menu View or press the right mouse button in the Diagram window Select the Random Number 0 1 function from Express Arithmetic amp Comparison Express Numeric and place it on the Diagram window Place the Multiply and Add functions from Express Arithmetic amp Comparison Express Numeric Select the Numeric Constant function from Express Arithmetic amp Comparison Express Numeric and place it twice on the Diagram see Figure 1 33 Make all the necessary connections Save the application as Voltage vi For building the VI icon please perform the following steps k Double click or right click and select Edit icon on the icon located in the upper left corner of the Panel window and the Icon Editor window will appear Figure 1 34 3 Icon Editor File Edit Tools Layers Help Templates Icon Text Glyphs Layers Catego a Filter templates by keyword All Templates P yaw Library Frameworks VI Frameworks CA R 0 X 0 G 0 Y 0 7 f B 0 Z1 OK Cancel Help Figure 1 34 The Icon Editor window 30 Lab 1 Introduction l Double click on the Select tool gt delete key to erase the actual icon to select the entire icon and then press the m Double click on the Rectangle tool H to create the icon border n Select the Icon Text tab and in the Linel text field wri
42. Device Name Set Point RPM F AL autotune P Overrange gt Overrange Ls Voltage Inpu Time Interval Wait Until Next ms Multiple b errorin on Fes pal A is Figure 6 13 The PID Control Speed Diagram with autotuning 22 Design the Panel and run the application Press the autotune F control A new window appears see Figure 6 15 Follow the instructions in order to find the optimum PID coefficients for your system Process Variable Puta Setpoint Variable AN Z 34 591195 Controller Output T U 49 396777 Process Monitor 100 i 00 00 09 050 Step 1 of 4 Set autotuning parameters Edit the values this wizard uses for the autotuning process Click the Next button to continue IMPORTANT Before you proceed you have to have at least initial values for Kc and Ti min that allow the controller to go above and below setpoint See Tuning Controller Manually in the a LahVIEW DIN Control Toolkit Licer Manual far mare detaile Previous PID Parameters _ Controller Type PI Ke 0 4856 SESO ET Ti min 0 0354 eo E Td min 0 008859 Relay amplitude 1 a J gt if a Control design Slow lt Back Cancel Figure 6 14 The autotuning of the PID control interface Lab 6 Introduction to Control 155 Exercise 6 2 Pulse width modulation in the PID algorithm for DC motor speed control A modern method used for delivering energy to a system is ba
43. NI ELVIS Computer Based Instrumentation Petru A Cotfas Daniel T Cotfas Doru Ursutiu and Cornel Samoila Center for Valorization and Transfer of Competence CVTC Creativity Laboratory Transilvania University of Brasov Romania d NATIONAL TECHNOLOGY amp SCIENCE PRESS ISBN 10 1 934891 11 8 ISBN 13 978 1 934891 11 7 Publisher Tom Robbins General Manager Erik Luther Marketing Manager Brad Armstrong Development Editor Catherine Peacock 2012 National Technology and Science Press All rights reserved Neither this book nor any portion of it may be copied or reproduced in any form or by any means without written permission of the publisher NTS Press respects the intellectual property of others and we ask our readers to do the same This book is protected by copyright and other intellectual property laws Where the software referred to in this book may be used to reproduce software or other materials belonging to others you should use such software only to reproduce materials that you may reproduce in accordance with the terms of any applicable license or other legal restriction Multisim and National Instruments are trademarks of National Instruments All other trademarks or product names are the property of their respective owners Lab 1 Lab 2 Lab 3 Lab 4 Lab 5 Lab 6 Lab 7 Contents Introduction Introduction to Testing Measurement and Data Acquisition Interfacing Basic Sensors Interfacin
44. NI ELVIS consists of a custom designed bench top workstation a prototyping board a multifunction data acquisition device and LabVIEW based virtual instruments This combination provides an integrated modular instrumentation platform that has similar functionality to the DMM oscilloscope function generator and power supply found on the classical laboratory workbench The development of PC based data acquisition and control systems using LabVIEW 2010 and NI ELVIS II has revolutionized the way lab work is performed in research establishments industry and many educational institutions Lab 2 Introduction to Testing Measurement and Data Acquisition 53 Data acquisition using the computer is now routine many labs have been set up for complete experiment operation under software control and today s graduating science and engineering students must be familiar with the concepts and techniques of computerized laboratories Students need to acquire communication teamwork and project skills to be prepared for today s team based work environment in science and industry In addition students need instruction in modern instrumentation including both plug in data acquisition DAQ boards and computer controlled standalone instruments For years LabVIEW users have found that they can develop applications four to ten times faster than with traditional programming languages As new technologies have rapidly emerged LabVIEW has taken advantage of
45. O m 3 WV Frameworks K CA O aK Q A i gt lt de a J R 0 X 4 G 0 0 B 0 Z1 OK Cancel J Help Figure 1 46 The Icon Editor window r Double click on the Select tool w to select the entire icon and then press the delete key to erase the actual icon s Double click on the Rectangle tool c to create the icon border t Select the Icon Text tab and in the Linel text field write Temp In the Line2 text field write K C F Figure 1 47 Then press the OK button 43 Icon Editor Sei File Edit Tools Layers Help Templates Icon Text Glyphs Layers Ll 1 f O Line1 text Temp W ii color Line 2 text KCF BBB Line 2 color T E F4 F O Line 3 text BBB Line 3 color 9 T Line 4 text BBB bine 4 color R TAA Figure 1 47 The Icon Editor window with Icon Text Build the connector by going through the following steps 36 Lab 1 Introduction u Right click on the icon and select Show Connector If the pattern of the connector is not convenient it s possible to select another pattern see Figure 1 29 v Using the Wire tool make the connections shown in the VI diagram in Figure 1 48 and in the Context Help window a 3 Temperature vi Front Panel n fon Ex File Edit View Project Operate Tools Window Help gt fe u 15pt Application Font J 2c oa e A gt h Kelvin 4 Context Help x Temperature vi Voltage Temperature Scale select Sc
46. OO OO zz Simulate Signal SIGNAL gt SS SPECTRUM Sampling Frequency Figure 2 4 Front panel and block diagram of Nyquist_Aliasing vi application Lab 2 Introduction to Testing Measurement and Data Acquisition 61 Exercise 2 3 Simple NI ELVIS control application For this exercise the student can build a simple control system see Figure 2 5 The following components are required DC motor we used a solar kit DC motor with operating voltage 1 2 V and operating current 55 mA One Beckman DC tachometer 6 5 V at 1000 RPM Figure 2 5 DC Motor connected to the DC tachometer Flexible connection between the motor and the tachometer This system is presented in Figure 2 5 and can be connected to the NI ELVIS system The DC motor can be controlled directly by the variable power supply VPS The output of the tachometer can be connected to the digital multimeter DMM and also to the analog input AIO use the NI ELVIS Scope The final measurement system is presented in Figure 2 6 The student can regulate the motor speed and measure the rotation with the DMM and visualize the signal and measure it with the NI ELVIS Scope connected at the AIO In Figure 2 7 we can see the PC desktop The following observations apply The NI ELVISmx Instrument Launcher is at the top of the picture 62 Lab 2 Introduction to Testing Measurement and Data Acquisition
47. R GND Vdd Figure 3 4 The TSL230R connection diagram Accelerometers Acceleration is the rate of velocity change over time It is a vector characterized by magnitude and direction The acceleration measurement unit in the SI is meters per second squared m s Often the acceleration is quantified in terms of g force g is the acceleration measure for gravity and is equal to 9 81 m s The accelerometer sensor measures the proper acceleration experienced by an object that has the sensor attached Therefore an accelerometer is an electromechanical device that measures acceleration forces One can distinguish two types of acceleration forces static forces which are the gravitational forces and dynamic forces which are caused by the movement or vibration of the object Using an accelerometer sensor movement tilt collision static and dynamic acceleration rotation and vibration can all be measured The structure of an accelerometer is based on a mass damped by a spring When acceleration occurs the mass is displaced until the spring compensates for the acceleration By measuring the displacement the acceleration can be determined Based on the types of sensing elements and the principles of their operation accelerometers can be classified as follows Capacitive accelerometers Piezoelectric accelerometers Piezoresistive accelerometers Hall effect accelerometers Magnetoresistive accelerometers Heat transfer a
48. VIS II Instrument Launcher 4 Launch the Oscilloscope instrument Figure 3 13 Eei Oscilloscope NI ELVISmx bol E E Basic Settings Channel 0 Settings E Channel 1 Settings E Source Source AIO AI 1 x J Enabled Enabled Scale Vertical Scale Vertical Volts Div Position Div Volts Div Position Div 1v 0 j 1v fi 0j Timebase Trigger Type Slope Time Div cise y Source Level v J Chan 0 Source 0 2 2ms i Instrument Control evice Acquisition Mode v Run Continuously Cursors Settings Display Measurements Run Stop Log Help CursorsOn Ci CHO C2 CHO x v cHo V cHi Autoscale r3 Ej L Figure 3 13 The Oscilloscope instrument panel Enable Channel 1 using the Enable control Select AIO for Channel 0 Source and AI 1 for Channel 1 Source Set the Scale Volts Div at the 1 V option for both channels a Choose the 2 ms option for Timebase 78 Lab 3 Interfacing Basic Sensors 9 Press the Run button and visualize the signals 10 Tilt the NI ELVIS platform on each axis one at a time and notice the modification in the signal 11 Activate the cursors using the Cursors On control 12 Set both cursors on CH 0 or CH 1 Move the cursors in a convenient position to measure the period of the signal T2 and then move again to measure the T1 time Calculate the acceleration using Equation 17 for different tilting positions of th
49. VIS II system and the prototyping board 10 Run the application and visualize the LED and the motor indicator 11 Using the control No of step launch the stepper motor to perform 48 steps By using the indicator on the motor shaft check that it performed a complete rotation 7 5 x 48 360 12 The application created makes possible the rotation of the shaft in one direction only 13 What do we have to change or add in the diagram to realize the movement of the shaft in both directions CW and CCW To realize the direction shift we will use the icon Select Programming Comparison Insert a Boolean control as follows in direction CW the icon Select lets the unmodified command sequence pass in direction CCW the icon Select will let the reverse control sequence pass the icon Negate is used and the rotation direction will be modified see Figure 4 16 Using the control No of step let the stepper engine perform 24 steps in the direction CW and then 24 steps in the direction CCW Using the indicator on the motor shaft check whether the initial position coincides with the final one 14 The shaft of a stepper motor describes a circular arc with the measure equal to the step For example in the case of the motor chosen for the experiment a circular arc is described with the measure of 7 5 in some applications a positioning with a smaller angle is required the angle to the center is equal to the measure of the circular arc describe
50. a simple counter circuit and there is the possibility of designing very simple drivers such as those having one transistor per coil A characteristic of unipolar stepper motors is their center tapped windings In practical use to reverse the direction of the field provided by the winding the two ends of each winding are alternatively grounded and the center taps of the windings are wired to the positive supply The number of phases is twice the number of coils each coil being divided in two The diagram in Figure 4 5 presents the connection of a 4 phase unipolar stepper motor If power is applied to the two windings in sequence a continuous rotation of the motor is obtained In the diagram that follows 1 means turning on the current through a motor winding When the command is set for the motor the two halves of each winding can t be excited at the same time Lab 4 Interfacing Actuators 95 Index 1a 1b 2a 2b Z Phase la E I e Vu 5s S Ee lt 0 l Phase 2a Stator a cab p o2a MMOL Stator b csr 2b Phase lb Vy Phase 2b b Figure 4 5 Unipolar stepper motor coil setup High torque and half step drive sequences are also possible in addition to the full step drive sequence In the high torque sequence for every motor step two windings are active simultaneously Approximately 1 5 times more torque 1s yielded by this two winding combination than by the standard sequence but twice the curren
51. a x OSeSeOSR amp Del EE e eSOAG Mem 2 a w nueit 4 08888 BERERE w HEBA y oO gE DIT g e mm m a gt CH Design Toolbox 2l x qe Dee NA E Pea T E hs Se Oe ites NOE NENAS SERES Si bouee gt ERR i PROTOTYPING BOARD al 3 2 relay circuit COPYPIGHT 2008 Leer Ss i aS relay circuit gutice Di ste ii relay circuit NI ELVIS z m mn zj mm aa H r ia Eri id a gt g Hierarchy Visibility Project View R relay cir 4 gt x 1 Multisim 2010 01 24 10 53 24 2 gt wo a an Results Nets Components PCB Layers Simulation A ur Figure 4 7 The Multisim schema for relay testing Start NI LabVIEW software and build the application that has the Panel and the Diagram shown in Figure 4 8 Place in the Diagram NI ELVISmx Variable Power Supplies express VI for the relay feeding Place in the Diagram NI ELVISmx Digital Writer express VI to realize the control of relay opening and closing Place in the Diagram the NI ELVISmx Oscilloscope express VI from Function Measurement I O NI ELVISmx Create controls for Channel 1 Device Name Horizontal and a numerical indicator for vizualizing the measured contact voltage Contact Resistance Place in the Diagram the NI ELVISmx Digital Multimeter express VI from the contact current measurement Create indicators for the Contact Voltage and the Contact Current
52. achine code The appeal of using LabVIEW is its graphical programming nature An interesting parallel can be drawn between the success and popularity of LabVIEW and the popularity of the Web In both cases it was not so much the underlying technology that was so innovative but rather the well designed graphical interface that made it accessible For LabVIEW that meant programming by wiring graphical objects together like building breadboard circuitry For the Web it meant a Web browser application 6 Lab 1 Introduction that involved little more than just pointing and clicking on images or words that were of interest and were hyperlinked to other places on the Web Therefore using LabVIEW to create Internet enabled applications Figure 1 3 brings some of the best user interface technologies together We see exciting possibilities for creating easy to use and intuitive networked applications that take virtual instrumentation to another level gt ServerTCP_ Sim v TELA i File Edit Operate Tools Browse 2 Window Help om on on Sample rate 1r puncte Sample rate ts Es a i Fomo es Domains _ IAA a aval aooo 10000 100000 4 HAN TA TT Figure 1 3 Server client application Basic Elements of LabVIEW Programming After you have installed the LabVIEW programming environment you can start LabVIEW from Start All Programs National Instruments LabVIEW 2010 LabVIEW LabVIEW will open its s
53. ad the values for which the relay closes and opens the circuit 12 To avoid running the program if an error appears the While loop conditional terminal can be used Lab 4 Interfacing Actuators 103 Exercise 4 3 Monitoring the auto induced voltage The elementary use of a relay is to close and open a circuit Since it is also one of the most widely used applications we wish to analyze in this experiment what is happening in the relay in an open close cycle Starting from this target it was observed that in the relay there are voltage spikes of hundred of volts with a limited duration ms when a relay is commuted off or on The appearance of the voltage spikes is explained as follows see Figure 4 10 When the switch is closed through the circuit a current flows through the coil from to creating a magnetic field When the circuit opens there is no current flow through the circuit and thus the magnetic field created collapses across the coil inducing a voltage that has a spike with the reverse polarity of few hundred volts Figure 4 10 The schemata for the spike voltage These voltage spikes that appear in the relay can lead to a malfunction or even the deterioration of the electronic equipment so methods must be found to eliminate or reduce these spikes There are three methods to eliminate the voltage spikes 1 using a resistance in parallel with the coil of the relay thus reducing spikes under 100 volts see Figur
54. ale Figure 1 48 Editing the Connector w Right click on the icon and select Show Icon x Save the application as Temperature VI and close the VI The Temperature measurementvi Using the two VIs developed previously we will create an application that simulates the temperature measurements Open a Blank VI from the start panel of the LabVIEW application b In the Diagram choose Select VI from the function palette A file explorer window will open Find the path to the first VI created in this example Voltage Read VI and select it Place this VI into the Diagram c Next select the Temperature VI and place it into the Diagram d Connect the Voltage output of the Voltage Read subVI with the Voltage input of the Temperature subVI e Create a control for the Scale Select input of the Temperature subVI by right clicking on the Scale Select terminal of the Temperature subVI and selecting the Create Control option Figure 1 49 from the pull down menu Lab 1 Introduction 37 OLTAGE TEE KGF Visible Items gt Description and Tip Breakpoint b Numeric Palette gt Control Replace gt Indicator Figure 1 49 The creation of a control from the Diagram f Create the Temperature and Scale indicators g The VI Panel and Diagram are shown in Figure 1 50 CG z 43 Temperature measurements vi Front Panel e F Temperature measurements vi Block Diagr Co CE File Edit View Project Operate Tools Window He
55. ation in NI Multisim Lab 6 Introduction to Control 159 serow ee Figure 6 19 The circuit for the PWM control of the DC motor speed on NI ELVIS F PID Control Speed PWM vi Block Diagram File Edit View Project Operate Tools Window Help DIA am F Ss bot 15pt Application Font Ro SA stop Device Name L autotuning f Speed parameters p A A Set Point RPM Actual Speed tty PG WA a Ej pey T output range E PID Output F PID Control Input Filter vi L d PID Autotuning vi TEREE j NI ELVISmx Fu PID Digital gt PID gains Ble PID gains 1000 gt Multimeter pease P DC Offset V i a JES io u i eeb Stop ae bXScale Multiplier Amplitude Vpp pa iin Overrange Time Interval Wait Until Next ms Multiple NIELVISmx we Function ES ge Generator 4 m Figure 6 20 The diagram of the PWM control application of the DC motor speed 160 Lab 6 Introduction to Control Exercise 6 3 The PID algorithm for temperature control This third exercise is dedicated to understanding how the PID algorithm is applied in the area of temperature control We will use a power resistor 5 W in the heater role As feedback sensor we will use a LM335 sensor see Chapter 1 The positive supply of the variable power supply VPS is used as heater supply The maximum current of the VPS is 500 mA so the minimum resistance of the heater that can be used is calculated using Ohm s
56. be found in the Modern or Classic palettes Figure 1 9 Lab 1 Introduction 11 Modern Classic bo Boolean String amp Path A r N i T umeri 00120 f oA b Array Matrix List Table amp Graph b m Z Saca BN Array Matrix List Table amp Ring amp Enum Containers Yo Ring eq 4 cp SEnu ey Variant amp Cl Decorations b Ring amp Enum Containers Refnum Figure 1 9 Supplementary controls and indicators palettes The Functions Palette This palette contains all the operations instructions commands and mathematical functions that are implemented in the graphical programming environment These are grouped either in classes characteristic of the operated data types or by programming methods The Functions palette contains dozens of functions Figure 1 10 This is why it is structured into libraries and sub libraries The palette s manipulation and activation mode is similar to the one from the controls palette from the main menu of the Diagram choose View gt gt Functions Palette or press the right mouse button in the Diagram The functions are characteristic to the Diagram The Tools Palette The Tools palette is dedicated to the selection of mouse operating modes operating tools required for the application design but also for debugging The palette and the most frequently used tools are presented in Figure 1 11 If the Automatic tool selectio
57. board 8 Run the application and visualize the signals 9 Itis observed that for the relay tested in this experiment the value of the voltage spike is 60 V The conclusion that can be drawn is that this relay has a resistance placed in parallel with a coil not a diode Lab 4 Interfacing Actuators File Edit View Project Operate Tools Window Help secs x Coil Voltage V Horizontal Sample rate S s iM Record length ik chan OSource WA o Acquire i z E N Position 4 i File Edit View Project Operate Tools Window Help SMENE 5p Appteaton ore tox ae I Device Name NI ELVISmx Digital Writer2 gt errorin gt Lines to Write a gt Lines to Write os PoOOUOUUU l m f ogoogo gg Figure 4 12 Panel and Diagram of Spike application 105 106 Lab 4 Interfacing Actuators Exercise 4 4 The control of the stepper motor Stepper motors have multiple applications in industrial domains and elsewhere Their use requires an ability to control the motors Starting from the stepper motor s composition a central shaft that can be a permanent magnet and the four coils that surround 1t the control consists of the excitation one by one of the coils after a certain sequence In this experiment we aim to control the stepper motor using an electroni
58. c circuit easily realized on the fast prototyping board of the NI ELVIS platform To develop a good understanding of the control we will set three stages In the first stage we will rotate the shaft step by step The second stage consists of changing the shaft rotation direction As many of the applications need a higher precision 1t is necessary that we realize a control half step by half step This technique allows the use of the same motor in more application types otherwise it should be changed In the third part the control will be realized for half a step with the possibility of changing the direction To realize the experiment we chose a stepper motor that allows for easy visualization of the shaft rotation and easy checking of the control s effectiveness For all three work stages the same component is used along with the same positioning of the mounting see Figure 4 13 1 Implement the control circuit shown in Figure 4 13 on the NI ELVIS H prototyping board using the following a Stepper motor feeding voltage 12 V 7 5 degrees per step coil resistance of 100 Q b Polarization resistances of the LEDs of 1 kQ c Four LEDs that have a single role in the circuit namely the visualization of the motor command LEDs of different colors can be used for each step d The integrated circuit ULN 2003 composed of seven pairs of NPN transistors and a high current that assures the command of the stepper motor It can be replaced wi
59. c unit for angular velocity is radian per second rad s RPM and rad s are both used to measure the same thing In order to convert RPM to rad s multiply the RPM by 0 10472 2 30 To convert rad s back to RPM multiply the rad s by 9 54929 30 r Students can develop the LabVIEW virtual instrument directly to make this conversion when they measure the motor speed 64 Lab 2 Introduction to Testing Measurement and Data Acquisition Notes Lab 3 Interfacing Basic Sensors 65 Lab 3 Interfacing Basic Sensors Instructor s Notes For measurements first of all it s necessary to have a way to convert the physical quantities into electrical quantities that can be digitized using data acquisition systems Sensors are used for this kind of conversion Using the NI ELVIS system many sensors can be studied in order to understand the control and the functionality of the sensors and to determine the sensors parameters a oe geeeeTrrrs E as ean se s OVA EA 4 Supplies 6 g z an AD iy of r Ver iene Seely Mex Output L3 VOC See 9 A ase AnCOE Fae Y Figure 3 1 The NI ELVIS Il system used for the study of sensors Goal This lab illustrates how LabVIEW and NI ELVIS II can be used for studying different kinds of sensors see Figure 3 1 For this lab a light sensor and a dual axis accelerometer are used Required Components The following components and software applications are required
60. ccelerometers Today s accelerometers are based on the MEMS Micro Electro Mechanical Systems technology This technology allows manufacturers to decrease the 70 Lab 3 Interfacing Basic Sensors dimensions of the sensors to allow for their use in different kinds of applications e g medical transportation navigation and electronics Important accelerometer specifications include Introduction to Accelerometers Communication represents the output type analog or digital It is determined by the hardware that is interfacing with the accelerometer Number of axes represents the number of directions in which the acceleration can be measured two axes or three axes Dynamic range represents the maximum amplitude that the accelerometer can measure Typically it is specified in g Frequency response trepresents frequency range where the output of the accelerometer is within a specified deviation typically 5 This specification 1s dependent on the mass the piezoelectric properties of the crystal and the resonance frequency of the case Noise depends on the sensor electronics amplifying circuit Resonance frequency trepresents the frequency at which the sensor resonates In order to avoid this situation the measurement frequency must be below the resonance frequency of the accelerometer Sensitivity trepresents the variation of the output depending on the force For the accelerometers with
61. cing Basic Sensors 73 g g Figure 3 7 The two axes inclination sensing from horizontal Memsic 2125 Connection Figure 3 8 shows the Mx2125 accelerometer connection to the NI ELVIS II prototyping board based on the connection diagram shown in Figure 3 9 Figure 3 8 The NI ELVIS II prototyping connection of the Memsic 2125 sensor 5 Memsic 2125 ACH2 lt __ ACHO lt __ X out ACH1 lt 220 Q Figure 3 9 The Memsic 2125 connection diagram 74 Lab 3 Interfacing Basic Sensors The three Mx2125 outputs are connected to the analog input channels as follows Y out is connected to AI 0 X out is connected to AI 1 and Temp output is connected to AI 2 AI 0 AI 1 and AI 2 are connected to the ground Y out and X out are connected to the AI channels via two 220 Q resistors The input voltage is connected to the 5V power and the ground pins 3 and 4 is connected to the GND References An 00mx 007 Application Note from Memsic Inc http www memsic com J Fraden 2004 Handbook of Modern Sensors Physics Designs and Applications Springer Verlag New York Introduction to Accelerometers http www omega com prodinfo accelerometers html MXD2125G amp M Application Notes from Parallax Inc http www parallax com S Soloman 1998 Sensors Handbook McGraw Hill New York TSL230 Datasheet from Parallax Inc http www parallax com Lab 3 Interfacing Basic Sensors 75 Exe
62. con on the Diagram and choose the Create Local Variable option Connect it to the PID Gains out output of the PID Autotuning VI 3 PID Control Speed vi vi File Edit View Project Operate Tools Window Help gt Device Name autotune F autotuning Set Point Fae Dev4 a Cc Speed Actual Speed controller type _ error out PID i 2105 07 status code cycles 33 S 0 Fi flo J 1500 0 source relay amplitude 10 00 gt 1000 0 IPBES Ae an eae D ETE di control specification g j x normal V 500 0 f PV noise level 40 10 oo F output range J i i gel PID gains 00 00 00 00 00 28 output high F Time 4 100 00 proportional gain Kc g 0 048565 l f A PID Output Plot 0 output low integral time Ti min 3 0 035435 mee J 0 00 derivative time Td min 9 0 008859 45 4 04 Set Point RPM Actual Speed SA 3 55 goo 2000 1200 ee 5 4 S 800 1200 gt 3 04 600 1400 A 1400 RI r k f 600 2 54 E gt 160 400 1600 1 400 i 2 0 i 200 00 00 00 00 00 28 L 5 2100 Time 200 1800 9 sE 0 2000 1000 000 Set Point Overrange Time Interval 7 STOP 7 1000 1000 86 Actual Speed InRange 4g 1 b Figure 6 12 The PID Control Speed Panel with autotuning 154 Lab 6 Introduction to Control D Control Speed vi vi Block Diagram Edit View Project Operate Tools Window Help DIA Sm e 25 lal WP a2 15pt Application Font Eo a
63. controls for adjusting the polarizing voltage of the MOSFET Offset and Voltage For the transistor used the voltage that has to be applied on the Gate to open the transistor is of 2 V offset and it can be raised to 9 V when the transistor is completely open The value attributed to the Voltage control is added to the value of the Offset voltage Lab 7 The Photovoltaic Characterization 179 6 Place in the Diagram the NI ELVISmx Oscilloscope express VI from Function Measurement I O NI ELVISm x EV characters ith VPSuppla vi File Edit View Project Operate Tools Window Help No of samples e512 Voltage V I I y I 100 200 300 400 500 600 Samples Solar Cell Voltage PlotO AN I 767 Solar Cell Current PlotO AN Current A T EV characteristic with VPSupplayvi Block Diag Sle es File Edit View Project Operate Tools Window Help 1 25 ual o EAZ Solar Cell Voltage Variable Power Supplies Figure 7 10 Panel and Diagram of I V characteristic for the solar cell 7 Create graphic indicators for measuring the voltage and the current debited by the solar cell their values having been previously mediated using the icon Mean 8 To measure the current generated by the solar cell the voltage that falls on a resistance is measured The resistance was previously measured precisely In the software the value of the voltage measured is divided by the
64. created previously Right click on the CHO Enable input choose the Create Constant option and choose for the created constant the True value Repeat the operation for the Trigger and Horizontal inputs choosing the Create Control option Add Extract Single Tone Information vi from Function Signal Processing gt Waveform Measurements This VI allows the determination of measured signal frequencies Detected Frequencies output By extracting the first element from the vector Detected Frequencies output by the function Index Array the vibration frequency of the system under study is determined and displayed in the indicator Detected frequency By using the function Get Waveform Components from Function Mathematics Probability amp Statistics the following components are extracted Y data values of the waveform and dt the time interval in seconds between data points in the waveform The acceleration sensor generates a signal proportional to the vibration motion of the system around half of the feeding voltage 1 5 V In order to eliminate this offset the mean value of the Y signal can be determined and subtracted then from the signal The mean signal is determined by Mean vi from Function Mathematics Probability amp Statistics By using Get Waveform Time Array vi from Function Programming Waveform the array of waveform time stamps 1s obtained By subtracting the first element from this vector the array of relative ti
65. cted from the 184 Lab 7 The Photovoltaic Characterization short circuit current of the characteristic obtained for the higher illumination level and using the reverse interpolation the corresponding voltage value is found For the interpolation the icon used 1s nterpol Id the path being Functions Mathematics Interpolation amp Extrapolation 7 Create indicator R for series resitance 8 Power on the NI ELVIS II system and the prototyping board 9 Run the application and visualize the signals Lab 7 The Photovoltaic Characterization 185 Exercise 7 3 The study of the solar panel The realization of the photovoltaic system begins with the building of the solar panel To obtain the panel the cells are generally bound in series but they can also be bound in parallel or in a mixed pattern Table 7 1 contains the modifications made to the important parameters when the cells are bound in parallel and in series np representing the number of cells bound in parallel and n standing for the number of cells being bound in series Table 7 1 Na e T o a eR Isc Rg Rsh Voc O V W Figure 7 15 presents the building steps from the solar cell to the mini panel or solar panel To perform the experiment in optimum conditions the whole panel must be uniformly illuminated If some cells are illuminated partially or not at all they can become consumers A solar mini panel was used instead of the solar panel for an easier per
66. d A smaller angle can be achieved by replacing the motor with one that has a smaller step angle or the same motor can be used in the half step mode Lab 4 Interfacing Actuators 111 4 Stepper Full Step with Direction vi File Edit View Project Operate Tools gt Device Name rA Dev4 vl No of Steps Delay LA i 43 Stepper Full Step with Direction vi Block Diagram File Edit View Project Operate Tools Window Help pe Lu ce No of Steps BaH l NI ELVISmx Device Name A Digital Writer2 IR Lines to Write gt errorin rd errorout 1 r NI ELVISmx i Digital Writer error out Variable Power Supplies2 Figure 4 16 Panel and Diagram of full step control with direction application Although it sounds complicated the only modification that takes place in the diagram is the use of another control sequence To realize the control of the stepper motor by half step in the diagram the sequence from Table 4 1 will be replaced with the one from Table 4 2 see Figure 4 17 aefa e o Table 4 2 112 Lab 4 Interfacing Actuators Figure 4 17 Panel and Diagram of half step control with direction application Lab 4 Interfacing Actuators 113 Challenge l Measure the contact resistance of the relay using only tools offered by NI ELVIS Digital Multimeter VI Oscilloscope VI NI ELVISmx Variable Power Supplies VI and Di
67. d with good dynamic stability Vibrations can be Harmful they need to be reduced or eliminated if possible Useful they need to be used even amplified if possible The vibrations can be subdivided according to different criteria If the dynamics of the vibratory phenomena are taken as a parameter then the vibrations can be Small variation frequency vibrations which can occur in building structures mechanical structures and in case of earthquake High variation frequency vibrations which are encountered in fluid environments chemical solutions etc due to heat conduction from a body with high temperature to one with a low temperature If the perturbing force value is taken into consideration as a parameter the variations include Free vibrations due to an initial impulse the disturbing force being zero Forced vibrations in which the disturbing force is different from zero and is applied all through the movement Variable characteristics vibrations which are due to variation in time of a given parameter the variation being generated by an interior or exterior cause 116 Lab 5 The Study of Vibration Another criterion for the classification of vibrations is the resistance force or forces from the system these include Damped vibrations for which the amplitude drops in time to zero the drop being caused by the resistance forces that cannot be neglected Undamped vibrations which is the ideal cas
68. duction in 1986 Because LabVIEW is easy to use interactive and graphical it helps users build measurement applications in the shortest amount of time and without requiring them to have a computer science degree Designed to enhance the productivity of both new and long time users LabVIEW gives them the ability to create code from VI Snippet images globally manage probes visualize data on new three dimensional graphs parallelize individual iterations of For loops reduce memory usage with data value references and more In addition to providing increased performance for parallel programming with multi core processors and field programmable gate arrays FPGAs LabVIEW provides access to the latest wireless technologies and simplifies real time math by streamlining mathematical algorithm design and deployment to deterministic hardware 2 Lab 1 Introduction NI ELVIS The National Instruments Educational Laboratory Virtual Instrumentation Suite NI ELVIS offers the most frequently used instruments in an electronics laboratory NI ELVIS eliminates the need for bulky equipment in the lab It also allows for the design of customized instrumentation that can be used and reused for specific projects The NI ELVIS system is built using NI hardware and software technology entirely and it has two main components 1 The bench top workstation NI ELVIS ID which provides instrumentation hardware and associated connectors knobs and LEDs A
69. e The coefficient of power on cycle which is the maximum power developed within a cycle The resolution that represents the smallest movement that can be controlled There are several types of actuators According to the actuators functioning principle they can be divided into two categories classical actuators and special actuators If we take into consideration the input signal used to control the motion of the active element the actuators are divided into the following categories Actuators controlled by a heat flux thermal Actuators electrically controlled by the intensity of the electric field Piezoelectric actuators with active elements from crystal piezoceramics or piezopolymers with various applications in the robotics industry CD player manufacturing and other areas Magnetostrictive actuators that function on the basis of the magnetostrictive effect whereby a ferromagnetic material modifies its dimensions under the action of an exterior magnetic field Actuators controlled by the induction of the magnetic field magnetic Actuators based on bimetals Actuators based on alloys with shape memory Actuators commanded optoelectrically or optothermally optic Electroreologic actuators Magnetoreologic actuators that use as a base element in their structure the magnetoreologic fluid or the ferrofluid a dispersion of magnetic particles in a base liquid Ferrofluids respond instantaneously when near an exterior magne
70. e when the resistance forces can be neglected because they are very small Auto vibrations where the resistance forces within the system maintain the vibrations having the same sign as the elastic force Vibrations can be Harmonic if they can be expressed by a single function sin or cos Nonharmonic representing more complex vibratory phenomena Nonharmonic vibrations are modulated either in frequency or in amplitude The vibrations can also be classified as a function of freedom degrees Functions of this parameter include Vibrations in systems having one degree of freedom Vibrations in systems having two degrees of freedom Vibrations in systems having more than two degrees of freedom Vibrations in systems having infinite degrees of freedom Goal The aim of the exercises in this section is to familiarize students with the theoretical concept as well as with the applications of ideal harmonic oscillatory movement damped and forced Students will learn how to design experiments that validate the theoretical solutions for the differential equations describing the damped and forced harmonic oscillatory movement The characteristic measures of oscillatory movement will also be highlighted Required Components Component requirements and software application are as follows LabVIEW 2010 Lab 5 The Study of Vibration 117 NI ELVIS II platform and NI ELVIS drivers The lamella for the oscillation Acceleromet
71. e 4 11 2 using a diode instead of the resistance therefore reducing the spikes completely and 3 using a capacitor which is a method less often used 12 W hv 200 Q 200 0 Figure 4 11 The schemata for the de spike voltage with resistor 104 Lab 4 Interfacing Actuators To focus on the voltage spikes from the relay and to measure their amplitude the following steps should be taken 1 Build the setup shown in Figure 4 6 2 Start NI LabVIEW software and build the application Panel and Diagram shown in Figure 4 12 3 Place in the Diagram the NI ELVISmx Oscilloscope express VI from Function Measurement I O NI ELVISmx 4 Create controls for Channel 0 Device Name Horizontal Trigger and a graph indicator Coil Voltage for vizualizing the measured signals In this experiment it is necessary to use the Trigger option of the oscilloscope to initialize the starting of measurement at the proper moment The negative slope is also set and at the same time the sampling rate has to be set as well as the number of samples needed to catch the voltage spike 5 Place in the diagram the NI ELVISmx Variable Power Supplies express VI needed to feed the relay coil with the voltage of 12 V 6 Place in the diagram the NI ELVISmx Digital Writer express VI to realize the control of the relay the opening and closing of the relay being realized using the Connect icon 7 Power on the NI ELVIS II system and the prototyping
72. e Mx2125 output signal is a 100 Hz PWM duty cycle signal in which acceleration is proportional to the ratio T1 T2 With 5 V input voltage and zero g the output is fixed at a 50 duty cycle and the sensitivity scale factor is set to a 12 5 duty cycle change per g T2 represents the pulse duration 10 ms 100 Hz and T1 depends on the acceleration at zero g T1 is 50 of T2 To determine the acceleration Equation 17 must be used 72 Lab 3 Interfacing Basic Sensors a g T1 T2 0 5 12 5 17 where a g 1s the acceleration Using the information from the An 00mx 007 Memsic application note the sensor output can be converted into angle units The relationship between the acceleration output and the angle according to Figure 3 7 is o gsin a g sin 8 a where a and a represent the acceleration on X and Y axes measured by Mx2125 g is the gravity acceleration and a p are the inclination angles To determine the angle value it is necessary to apply the inverse sine function to Equation s 18 a sin A arosin 19 B sin 6A l arcsin 1 or sin A arosin i B sin A arcsin 0 if a and a are taken in g units This configuration can be used in applications that don t require an inclination angle greater than 60 because for inclination angles greater than 60 very few changes will appear at the accelerometer outputs because of the sine function Lab 3 Interfa
73. e NI ELVIS platform Lab 3 Interfacing Basic Sensors 79 Exercise 3 3 Mx2125 LabVIEW programming The second exercise with the accelerometer focuses on learning how to program the Memsic 2125 in LabVIEW For this experiment the same connection will be used but a mobile prototyping board and a protractor as shown in Figure 3 14 will also be used a U type holder f Bubble level b Mobile cross bar g Positioning gear c Mobile prototyping board h Power wires d Protractor i Output connection wires e Memsic 2125 Figure 3 14 The setup for one axis tilting of MX2125 1 To build the setup shown in Figure 3 14 Create a U type holder using two 15x0 5x2 cm aluminum flat bars and a 6 cm square made of melamine PAL On the top of the holder insert a mobile cross bar for anchoring the mobile prototyping board 80 Lab 3 Interfacing Basic Sensors Fix the protractor on the mobile cross bar axis in a convenient manner and fix the positioning gear on the opposite side Place Mx2125 on the mobile prototyping board Make the sensor connections for power and output to the NI ELVIS prototyping board For a feedback check that you can place a bubble level on the mobile prototyping board Start the NI LabVIEW software and build the application shown in Figure 3 15 and Figure 3 16 File Edit View Project Operate Tools Window Help Figure 3 15 The Memsic 2125 v1 vi panel Lab 3 Inte
74. e accumulated error is multiplied by K the integral gain and is then added to the controller output Because the integral term accumulates the values of the error the integral control can be accredited with the past term Since the integral term is dependent on the accumulation of the past errors it will lead to the process variable overshooting the set point value Figure 6 5 The integral term is often related to the proportional gain by K a 72 where 7 1s the integral time 144 Lab 6 Introduction to Control Generally the integral controller is not used by itself It is used together with the proportional controller giving the PI controller PV Setpoint 12 10 w gei 2 6 E r 4 Setpoint PV Ki 0 004 2 PV Ki 0 008 PV Ki 0 016 1 MN mA A A An N NEEE 0 2 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Samples Figure 6 5 The effect of K increasing As can be seen in Figure 6 5 the integral term tends to slow down the system reaction Derivative From Equation 70 the derivative term D term can be extracted as ult K el 73 where K4 is the derivative gain The derivative term is determined by the rate of error change The derivate represents the slope of the error curve so the derivate term indicates the future tendency of the error Due to this feature of the derivative term we can think about it as a future term Because the derivate inc
75. e by Radius VI Inverse sine and Index Array functions are used In order to calculate the center of 2D Picture indicator the Draw Area Size property node is used Right click on 2D Picture and from the pull down menu select the option Create Property NodeDraw Area Size For the Inverse Sine output conversion from radians into degrees Equation 22 is used o a rad 180 22 For picture representation the calculated angles must be converted in pixels For this Equation 23 is used DAS PC 90 23 where PC is Pixel Center DAS is Draw Area Size of the 2D Picture and T is the cluster of the a and p angles Save the application with the Circular level name Power on the NI ELVIS II system and the prototyping board Run the application and tilt the mobile prototyping board on both X and Y axes Notice the movement of the blue circle inside of the 2D Picture When the mobile prototyping board is in the horizontal position the blue circle must be inside of the green circle When the mobile prototyping board is in the vertical position the blue circle must be on one of the borders of the 2D Picture Lab 3 Interfacing Basic Sensors TEile Edit View Project Operate Tools Window Help 85 File Edit View Project Operate Tools Window Help 2D Picture 7 72 BHE 115000 Chan 0 Source Edge v Negative 5 aM Draw Circle by Radius vi SIE i Pe alo 15 Aep
76. e converter are integrated into a single CMOS chip with a PDIP 8 package The TSL230R sensor comes in three versions TSL230R LF TSL230AR LF and TSL230BR LF with different absolute output frequency tolerances 5 10 and 20 respectively Because all inputs and outputs are TTL compatible this sensor can be easily integrated with a microcontroller The functional diagram is presented in Figure 3 2 S Output a Photodiodes array Current to Frequency Converter gt a a a a a x Light S1 S2 S2 S3 OE Figure 3 2 The functional diagram of the TSL239R LF The SO and S1 inputs represent the sensitivity select inputs and S2 and S3 represent the scaling select inputs of the output frequency Table 3 1 and Table 3 2 show the selectable options for S0 S1 and S2 S3 inputs 68 Lab 3 Interfacing Basic Sensors Table 3 1 Sensitivity selection Table 3 2 Frequency scaling selection olof ofif 2 pt o l0 The TSL230R Connection Figure 3 3 shows the TSL230R LF test connection on the NI ELVIS II prototyping board The connection is based on the diagram shown in Figure 3 4 Figure 3 3 The NI ELVIS II prototyping connection of the TSL230R sensor To demonstrate the TSL230R functionality the SO S3 inputs were connected to the digital input output channels DIO0O DIO3 Using these channels the TSL230R can be configured according to Table 3 1 and Table 3 2 Lab 3 Interfacing Basic Sensors 69 TSL230
77. e high and unique low connection for each channel Data acquisition devices have either single ended or differential inputs and many devices support both configurations Like AI0 and AI on the NI ELVIS Prototyping board Single ended input SE refers to the way a signal is wired to a data acquisition device In single ended wiring each analog input has a unique high connection but all channels share a common ground connection Data acquisition devices have either single ended or differential inputs Many support both configurations Resolution refers to the smallest signal increment that can be detected by a data acquisition system Resolution can be expressed in bits in proportions or in percent of full scale For example a system can have a 12 bit resolution one part in 4 096 resolution or 0 0244 percent of full scale 58 Lab 2 Introduction to Testing Measurement and Data Acquisition Sample rate the speed at which a data acquisition system collects data The speed is normally expressed in samples per second For multi channel data acquisition devices the sample rate is typically given as the speed of the analog to digital converter A D To obtain an individual channel sample rate you need to divide the speed of the A D by the number of channels being sampled Interfaces GPIB Serial RS232 RS485 USB and so forth NI ELVIS IT uses USB for the PC connection Using the Analog Digital Resolution VI see Fi
78. e second term of the equation represents the recombination of the carriers in the space charge region of the junction If the current caused by thermionic emission is also taken into consideration the mathematical model as well as the equivalent circuit modifies In the mathematical model another exponential term appears and the equivalent circuit is given in Figure 7 3 d The considerations regarding the mathematical models and the equivalent circuits presented here start from the presumption that the solar cell is illuminated If the performances of the solar cell in the dark are under observation Iph disappears from the mathematical models The most general mathematical model for most of the solar cells studied in the dark becomes Equation 86 where the third term can be neglected given that the recombination component is much higher than the thermionic component Stutenbaeumer Mesfin I 1 CEA i PL f ni 86 m kT m kT R The Solar Panel A Si solar cell generates a typical open circuit voltage of 0 6 V regardless of its area The short circuit current is proportional to the area and generally has values in the range from 30 to 40 mA cm The maximum power generated by the solar cell is lower than Vo Is as can be seen in Figure 7 2 This leads to the need to raise the maximum power generated We can raise the generated power if 172 Lab 7 The Photovoltaic Characterization More cells are bound in series and the
79. ed using indicators Controls and indicators belong to the VI Panel The palette that offers access to all available controls and indicators is called Controls and is shown in Figure 1 6 Lab 1 Introduction 9 Controls Q Search amp Customizer v Modern 4 abc i be Poth Numeri Boolean String amp Path 7 le 4 1E Ts Array Matrix List Table amp Graph fa oq a cia ei Ring amp Enum Containers yo co gt OA gt m Ou B Variant amp Cl Decora tions Refnum gt System gt Classic v Express 4 H y 4 H Num Ctrl Buttons Text Ctrls N i r i 4 o age a User Ctrls Num Inds LEDs gt TextInds Graph Indica gt Control Design amp Simulation gt NET amp ActiveX gt Signal Proc g gt Addons gt User Control Select a Control gt NXT Robot gt RF Communica tions J gt Vision Change Visible Palettes Figure 1 6 Controls and indicators palette called Controls The controls palette can be activated from the main menu View gt gt Controls Palette or by pressing the right mouse button in the Panel In the second case the controls palette can be hidden by pressing the Esc key from the keyboard or by clicking the left mouse button while outside the palette To fix the palette to the Panel press the pin in the left upper corner When the controls palette is fixed navigate through the palette by pr
80. eful to use such a transistor in order not to raise the resistance in the measurement circuit e The polarizing resistance of the MOSFET transistor with the value of 5 6 kQ The electronic circuit was realized in Multisim as well for an easier implementation see Figure 7 9 Start the NI LabVIEW software and build the application that has the Panel and the Diagram shown in Figure 7 10 Place in the Diagram NI ELVISmx Variable Power Supplies express VI for the relay feeding 178 Lab 7 The Photovoltaic Characterization 4 Solar cell Multisim Solar cell l aes File Edit View Place MCU Simulate Transfer Tools Reports Options Window Help l a x JO ee OSQ BBC S e BSBA M Mem a w nueit r 0888 SCRE Rew eer Bee Eam y oe FoF g l l m a S SS z Design Toolbox Dead z NIELVISISERIES PROTOTYPING BOARD B A Solar cell Solar cell Circuit2 NI ELVIS BA Sobr cel Ld gt Multisim 2010 05 14 00 27 02 o o v a n 3 Eile Edit View Tools Options Window Help 5 x possano lBaals Solar cell 33 3D View Circuit2 NI ELVIS al gt Hierarchy Visibility Project View Multisim 2010 05 14 00 27 02 Spreadsheet View x Figure 7 9 The Multisim schemata for raising the I V characteristic 5 Create
81. el of the LabVIEW application b Select a Numeric Control from the Express Numeric Controls palette place it on the Panel and call it Voltage c Select a Numeric Indicator from the Express Numeric Indicators palette place it on the Panel and call it Temperature d Select a String Indicator from the Express Text Indicators palette place it on the Panel and call it Scale e Extend the Controls palette as shown in Figure 1 38 Controls Q Search Modern d System Classic gt Express gt Tu gt gt gt 4 m z Ari mti Controls Search s gt gt gt gt O amal 2 Express gt gt z i W u i En Dow Control Design amp Simulation 24 4 mri NET amp ActiveX gt 0210 r z Signal Processing gt SkA ies Addons gt User Controls b User Controls b Select a Control Select a Control RF Communications b RF Communications b A aU Figure 1 38 The extension of the Controls palette 32 Lab 1 Introduction f Select the Enum control from the Modern Ring amp Enum palette Figure 1 39 place it on the Panel and call it Scale Select 1 Controls Q Search Modern gt System 1 0 Modern Classic Express amp gt A 4 garm af gt gt gt nm Ed finaz mR gt diwn Ring amp Enum Control Design amp Simulation l Enum NET amp ActiveX i m ma nn Rin Rii Enum Signal Processing i P ges ail g
82. ells if they are bound in series or in parallel thus creating mini solar panels For the mini solar panels the I V characteristic is also raised and interpreted Required Components Component requirements and software application for relays testing include the following LabVIEW 2010 NI ELVIS II platform and NI ELVIS drivers MOSFET transistor IRF2907z resistance of 5 6 KQ resistance of 0 1 Q One solar cell 0 5 V 400 mA dimensions L x W 76 x 46 mm operating temperature 20 to 80 C Two solar cells 0 51 V 200 mA dimensions L x W 50 x 23mm operating temperature 20 to 80 C Lab 7 The Photovoltaic Characterization 167 One halogen bulb 35 W 12 V The power supply 12 V 4A 168 Lab 7 The Photovoltaic Characterization Background The Solar Cell The solar cell is the heart of a photovoltaic system In order to create an optimum photovoltaic system the cells that it comprises must be carefully chosen The internal and external parameters of the cells must be determined in order to make this choice In a panel only the so called twin cells must be used meaning the cells that have very close parameter values Current Intensity A V max Moe Voltage V Figure 7 2 The l V Characteristic for solar cells The main study method for solar cells parameters uses the current voltage characteristic I V see Figure 7 2 The main parameters that must be taken into account for measuri
83. enson ore EA NIELVISmx Hb CH0 Enabie_ Hb crt Enable gt Device Name b erorin T Horizontal p Stop ELVIS Channel Orf Merge Signals a sop peoo Figure 3 19 Sensing the inclination of the two axes from horizontal the Diagram 86 Lab 3 Interfacing Basic Sensors Challenge Using the Mx2125 accelerometer develop an application to study a pendulum Place the Mx2125 in a box or preferably a ball that is suspended from a high holder You can use the Mx2125 connection wires as suspension cord Fix the cord length and calculate the period of the resulting pendulum using Equation 24 T 27 E 24 amp where T is the oscillating period of the pendulum is the length of the pendulum cord and g is the gravitational acceleration Modify the Circular level application to visualize the angles also on the graphs the Waveform Chart can be used Using the time information from the dynamic data of the NI ELVISmx Oscilloscope Channel 0 and Channel outputs calculate the pendulum period Notes Lab 3 Interfacing Basic Sensors 87 88 Lab 4 Interfacing Actuators Lab 4 Interfacing Actuators Instructor s Notes Actuators are controllable execution elements that transform the input energy electrical magnetic thermal optic or chemical in mechanical work The conversion of the input energy into effective output energy is realized with electrical and magnetic fields as a result of ph
84. er Analog Devices ADXL325BCPZ Electromagnet used for forced oscillation Support 118 Lab 5 The Study of Vibration Background Oscillatory Movement The focus in this section 1s on the linear undamped harmonic oscillatory movement which is the simplest vibratory movement In this case we deal with vibrations in systems having one degree of freedom The system in Figure 5 1 can be used to describe theoretically the oscillatory movement It consists of a body of m mass tied with a spring with the elastic constant k to a rigid wall Figure 5 1 Mechanical model for harmonic vibration If the system is taken out of the state of equilibrium it will make an alternative motion around the equilibrium position due to the elastic force The movement of the body with a mass m will be considered without friction The motion equation 1s found using the second principle of dynamics A differential equation of the second degree is thus obtained mx kx 26 where x x t represents the motion and the minus is due to the elastic force opposing the deformation of the spring Dukkipati et al Timoshenko Equation 26 can thus be written as x ue 0 27 m Lab 5 The Study of Vibration 119 Equation 27 is a second degree differential equation with constant coefficients and is homogenous k m is noted as s The measure noted as is called proper pulsation of oscillatory movement The solution of the differential Equation 27
85. eral holes connected through to the data acquisition board There is also a front interface on the workstation with controls for a few select instruments Hands on learning of the kind made possible by NI ELVIS and LabVIEW allows students to achieve what experts call authentic learning Authentic learning situates students in learning contexts where they encounter activities that involve problems and investigations reflective of those they are likely to face in their real world professional contexts Brown Collins amp Duguid 1989 Lave amp Wenger 1991 Herrington and Oliver 2000 have identified nine characteristics of authentic learning l 2 Authentic contexts that reflect the way the knowledge will be used in real life Authentic activities that involve complex ill defined problems and investigations Access to expert performances enabling modeling of processes Multiple roles and perspectives providing alternative solution pathways Lab 2 Introduction to Testing Measurement and Data Acquisition 55 Collaboration allowing for the social construction of knowledge Opportunities for reflection involving metacognition 5 6 7 Opportunities for articulation to enable tacit knowledge to be made explicit 8 Coaching and scolding the teacher at critical times 9 Authentic assessment that reflect the way knowledge is assessed in real life All of these are well evidenced in our NI ELVIS Lab VIEW context exampl
86. es NI ELVIS connected with LabVIEW and running on one computer offers to the learner a recognized platform for testing measurement and data acquisition Figure 2 2 The NI ELVIS II Station References Bogdan M Panu M amp Viorel A 2007 Teaching Data Acquisition on a Virtual Laboratory The 4th Balkan Region Conference on Engineering Education ISSN 1843 6730 12 14 July Sibiu Romania Brown J S Collins A amp Duguid P 1989 Situated Cognition and the Culture of Learning Educational Researcher 18 1 32 42 Cerna M amp Harvey A F 2000 The Fundamentals of FFT Based Signal Analysis and Measurement National Instruments Application Note 041 Herrington J amp Oliver R 2000 An Instructional Design Framework for Authentic Learning Environments Educational Technology Research and Development 48 3 23 48 56 Lab 2 Introduction to Testing Measurement and Data Acquisition Lave J amp Wenger E 1991 Situated Learning Legitimate Peripheral Participation Cambridge University Press Cambridge UK Lab 2 Introduction to Testing Measurement and Data Acquisition 57 Exercise 2 1 Analog digital converter resolution Data acquisition systems as the name implies are products and or processes used to collect information to document or analyze some phenomenon In the simplest form a technician logging the speed of one DC motor on a piece of paper i
87. essing the button that corresponds to the desired libraries or sub libraries If the palette is not fixed navigate by moving the mouse cursor over the desired buttons The existence of a sub library is indicated by an arrow placed in the upper right corner of the corresponding button The following are basic control and indicator types that can be used in LabVIEW Figure 1 7 and Figure 1 8 Numeric controls Buttons and switches Text controls Numeric indicators LEDs Text indicators Graph indicators 10 Lab 1 Introduction Buttons amp Switches aw AT search S customizes pia Numeric Co Numeric Indi Time Stamp Time Stamp 107 Vertical Fill SI Vertical Poin Vertical Prog Vertical Grad omen Rocker Rocker Slide Switch Slide Switch Horizontal Fi Horizontal P Horizontal Pr Horizontal G yy a va EE SG J p r Toggle Switch Toggle Switch Push Button 3 Lod Text Button OK Button Cancel Button Stop Button Framed Colo i Bran String Ctrl Text Ring Menu Ring File Path Ctrl amp Customize H i a Num Ind Progress Bar Grad Bar Progress Bar Grad Bar 1 a a 100 8 me o amp j Gauge SS oc FTG search amp customizer Square LED Round LED abc Taea Figure 1 8 Basic indicators palettes In certain applications a larger variety of controls and indicators is required These can
88. f inflection POI Figure 6 7 The process reaction curve Knowing the L and T parameters Ziegler and Nichols propose the rules shown in Table 6 1 to calculate the PID coefficients Table 6 1 Setting the PID coefficients based on the process reaction method Control type The K and K4 coefficients can be calculated using Equations 72 and 74 Lab 6 Introduction to Control 147 Ultimate cycle tuning method Another variant of the Ziegler and Nichols method is the ultimate cycle tuning method In the first step of this method the K and K4 coefficients are set to zero Then K is slowly increased until the process output starts to oscillate This value of K 1s called ultimate gain and it is denoted by Ky The oscillation period is measured and is denoted by Puy Using Ky and Py values the PID coefficients can be calculated as shown in Table 6 2 Table 6 2 Setting PID coefficients based on the ultimate cycle method The values shown in Table 6 2 are calculated for a quarter amplitude decay response which means that the amplitude decreases by a quarter on each oscillation In order to obtain a response with or without overshoot the PID coefficients in Table 6 3 can be used Table 6 3 Setting PID coefficients for a response with or without overshoot 148 Lab 6 Introduction to Control In industry the PID tuning is made using dedicated software packages and the manual calculation methods presented previousl
89. formance of the experiment It is composed of two twin solar cells bound at first in series and then in parallel The area of these solar cells was chosen so that they would be uniformly illuminated Another problem that appears if the panel under characterization is a 36 cell panel bound in series is the fact that the generated voltage is 21 V surpassing the measurement capabilities of the board A voltage divider can be used tosolve this problem The experiment consists of raising the I V characteristic of the solar mini panel The I V characteristic is graphically compared with the short circuit current the open circuit voltage and the series resistance of the cell when the cells are bound in series and in parallel The steps in realizing the experiment are as follows 1 Build the setup shown in Figure 7 16 to include a the halogen bulb b the two solar cells c the command circuit which is similar to the one used for raising the characteristic of a solar cell and d a different positioning of the 186 Lab 7 The Photovoltaic Characterization TMG NE TU A Figure 7 15 From the solar cell to the solar panel a The solar cell b The mini panel c The solar panel 72 solar cells wire the cells are bound in series or in parallel or the second cell can be shunted Start NI LabVIEW software and build the applications Panel and Diagram shown in Figure 7 10 and Figure 7 11 These applications permit the rai
90. g Actuators The Study of Vibration Introduction to Control The Photovoltaic Characterization 51 65 88 115 139 165 Lab 1 Introduction l Lab 1 Introduction A computer based instrument is assembled inside or outside a computer and uses the computer for data acquisition processing measurement display and communication A computer based instrument consists of the following components 1 The computer itself which can be a desktop laptop or PXI industrial measurement computer 2 Hardware for data acquisition and or instrument communication This hardware may be a plug in data acquisition board GPIB USB serial or wireless device that acquires data from an external source and brings the data into computer memory for processing display and communication The NI ELVIS I workstation 1s a good example of a USB data acquisition computer peripheral 3 Computer based instrumentation software LabVIEW LabVIEW is a graphical programming environment used by millions of engineers and scientists to develop sophisticated measurement test and control systems using intuitive graphical icons and wires that resemble a flowchart LabVIEW offers strong integration with thousands of hardware devices and provides hundreds of built in libraries for advanced analysis and data visualization LabVIEW is a software platform that 1s scalable across multiple computer targets and operating systems and has been an industry leader since its intro
91. ge value of the pulse wave becomes DT Tai 80 Y Ymax 7 80 Figure 6 16 shows average values of the pulse waves obtained for different duty cycle values 10 Vi DT 20 ha V1 V2 V3 g V2 DT 40 e 10000 20000 4 0000 8 V3 DT 80 A J 4 i q 4 I T zT I I I l I I I i KIN I I l I I I l I i 7 I l I I I 0 002 004 0 06 0 08 01 012 014 016 018 02 Samples Figure 6 16 Average values of the pulse waves The PWM technique is used in many applications such as controlling the voltage generated by a computer power supply controlling the speed of a DC motor controlling the temperature of a heater and so forth This exercise is dedicated to the application of the PID control using the PWM for controlling the speed of the DC motor used in the first exercise To use the PWM control it is necessary to change the electronic circuit for powering the DC motor The schema is presented in Figure 6 17 and is based on a Lab 6 Introduction to Control 157 MOSFET transistor The pulse wave is generated with the NI Function Generator set on the square waveform In order to generate only positive pulses an offset is added E DC speed PWM Multisim DC speed PWM ann File Edit View Place MCU Simulate Transfer Tools Reports Options Window Help 5 x DSeOIese st SS p meSHAW Mem 2 aw wm inueit l BAQQg oe RRR twee eee eae Bee emyY eo gE BS eS 2 mm ew Se gt CH
92. gital Writer express VI Realize an application that allows the monitoring of the contact resistance of an electromagnetic relay One of the possibilities is to stress the electromagnetic relay with a fixed number of pulses applied to the coil and to measure the contact resistance Thus the monitoring is continuous Realize a complex application to test a relay that contains all of the three tested parameters Realize a complex application to control the stepper motor in full step and half step mode and its rotation direction For the applications created for the testing of the stepper motor four DIO ports are used Realize a control setup that uses only two DIO ports you can use the notes from http www 805 projects net stepper motor interfacing stepper motor connections php 114 Lab 4 Interfacing Actuators Notes Lab 5 The Study of Vibration 115 Lab 5 The Study of Vibration Instructor s Notes Vibratory or oscillatory movement occurs when the parameters that describe the system movement alternatively vary in time around the values corresponding to the reference state From now on the movement will be named vibration or oscillation for simplicity Vibration study has been and still is a research priority since vibrations have to be taken into consideration when Secure buildings have to be realized The working locations for the human operator are built High performance machines are built and are provide
93. gle diode model for the two illumination levels 182 Lab 7 The Photovoltaic Characterization Vitk ti AA re a 1 88 V R I gt 1 lal a 1 89 Taking into consideration Equation 90 as V is an independent variable V LR V LR 90 And the translation for the current 91 L SAL 91 Equation 87 is obtained Figure 7 13 l V curves used to determine the series resistance To practically realize the experiment the following steps must be taken 1 Build on the prototyping board of NI ELVIS the setup shown in Figure 7 8 2 Start the LabVIEW software Build the application that has the Panel and the Diagram shown in Figure 7 14 The new version of the software used for Exercise 7 1 is used to raise the characteristic I V of the solar cell The data for two I V characteristics are saved for two illumination levels of the solar cell The illumination levels can be realized either by varying the voltage drop on the bulb or by varying the distance between the bulb and the solar cell Using the software series resistance R see Figure 7 14 the saved data are read using the express icon Read from Measurement File Lab 7 The Photovoltaic Characterization 183 J Series Resistance Rs File Edit View Project Operate Tools Window Help gt een Filenamej Solar Cell I V characteristic Filename 2 q PUsers Documents Carac2 vm Ki Current A T Series Resistance Rs vi B
94. gure 2 3 the student can practice and better understand the ADC resolution Analog Digital_Resolution vi Front Panel File Edit Yiew Project Operate Tools Window Help o gt a u 13pt Application Font x Bodi e SIGNAL SIGNAL Input Signal A fii FREQUENCY Sine 2 Aquired Signal is 9 Ba 72 6 52 a 32 2 ie O1 Resolution Sasi Range ar Amplitude A F 1 1 1 1 1 1 1 1 1 1 Step Height mv 400 600 800 1000 1200 1400 1600 1800 2000 Time File Edit View Project Operate Tools Window Help JA m es bal of 13pt Application Font oria AE IGNAL x y b m Figure 2 3 Front panel and block diagram for Analog_Digital_Resolution VI application Lab 2 Introduction to Testing Measurement and Data Acquisition 59 Exercise 2 2 Sampling rate Nyquist rate The analysis of real world signals is a fundamental problem for many engineers and scientists and especially for electrical engineers since almost every real world signal see the case of different types of sensors is changed into electrical signals The sampling frequency determines the quality of the analog signal that is converted and analyzed Higher sampling frequency achieves better conversion of the analog signals The minimum sampling frequency required to represent the signal should be at least twice the maximum frequency of the analog signal under test this is called the Nyquist rate If
95. gy Vol 18 pp 501 512 Lab 7 The Photovoltaic Characterization 175 Exercise 7 1 Raising the I V characteristic for a solar cell The importance of raising the I V characteristic of the solar cell was described previously In this experiment the method to obtain this characteristic will be described as well as the work conditions that must be taken into account The raising of the I V characteristic can be performed in natural light conditions under solar radiation as well as in lab conditions In the lab the characteristic can be obtained when the cell is illuminated as in Figure 7 2 or when it is not illuminated dark condition as in Figure 7 7 Ln 4 oo o 1 o2 oa O 4 os O6 i OB AM Figure 7 7 The dark semi logarithmic I V caracteristic for the solar cell There are several methods for the raising of the I V characteristic Some of them include using the electronic load using a capacitor as a variable charge Cotfas D Cotfas P using a MOSFET and using a variable resistance a digital potentiometer can be used In order to be viable for raising the I V characteristic of the solar cell a device has to fulfill the following conditions It must be accurate It must be fast because the parameters of the cell modify with the temperature of the solar cell For example the open circuit voltage drops with 2 mV C If the characteristic is raised in a few tens of seconds use of a thermostat is compulsory The
96. he Diagram window as shown in Figure 1 15 J Lab 1 Introduction 17 solute Va Square Root Square Negate Reciprocal Sign i Num Const Random Num gt m Inf Machine Eps Math Consta Figure 1 16 Navigating through the Functions palette Connect the b icon with the x terminal of the Negate function using the Ka Pass over the b icon with the mouse pointer until this pointer takes the connecting tool form When that happens press the left mouse button once and move the mouse over the x terminal of the Negate function until the terminal starts blinking Then press the left mouse button once If the connection is successful the wire will have an orange color Connecting tool Connect all terminals as shown in Figure 1 15 When all the connections are successful the application 1s finished Running the application k Before running the application it is necessary to introduce the values for the equation coefficients a and b For this activate the Panel window by clicking on the left mouse button on the Panel window or by selecting Show Panel from the Window pull down menu Pass the mouse pointer over the b control in the Panel window until the pointer takes the operating tool form bj Press on the b control arrows until you receive the desired value Repeat the operation for the a control Run the application Press the Run button from the toolbar gt Notice the results shown in the x ind
97. he Panel of the application Place in the Diagram the NI ELVISmx Oscilloscope express VI from Function Measurement I O NI ELVISmx Create controls for Channel 0 Channel 1 Device Name Horizontal and create two indicator graphs for vizualizing the measured signals of the coil voltage and contact voltage To measure the voltage on the coil we used a voltage divider This is necessary as the value of the voltage on the coil exceeds the maximum limit of volts that can be measured with the NI ELVIS application Create a graph indicator for hysteresis representation on this graph the Contact Voltage versus Coil Voltage are represented Power on the NI ELVIS II system and the prototyping board 10 Run the application and visualize the signals 102 Lab 4 Interfacing Actuators File Edit View Project Operate Tools Window Help Coil Voltage Ploto A i n 1 Coil Voltage V A 5 vi Channel 1 Source SCOPE CH 1 Channel 0 Coupling Channel 1 Coupling 9 DC Channel 0 Probe Channel 1 Filter PlotO 1 78173 0 10928 Zj Coil Voltage V 4 File Edit View Project Operate Tools Window Help Lle 10 2 25 balaa 25et Application Font vifio eea Triangle Waveform vi Get Waveform Components gt errorin gt Lines to Write aml Figure 4 9 Panel and Diagram of the Hysteresis application 11 Activate the cursor for the Hysteresis graph and re
98. i AS Xp 18 a solution of Equation 53 it has to be verified therefore we obtain 130 Lab 5 The Study of Vibration A sin w t 9 264 0 cos t p 56 A a sin w t o q sin t e For each value of t Equation 56 must be verified As there are two unknown quantities e and g two values will be considered for et to facilitate calculations The values taken are 0 and z 2 For these values Equation 56 becomes A a sin 264 cos 4 sin p qsin0 57 A4 0 in Z p 204 0 cos p A O in Z p q sin 58 2 2 2 2 By elementary calculations the preceding equations become A lo sin 9 264 a cosp 0 59 A lo 0 Joos p 2064 sing q 60 Equation 59 is used to calculate the expression for and therefore 200 t20 61 EP o o 61 The amplitude of the forced oscillation is obtained by summing up Equations 59 and 60 previously having been squared A 62 l o 260 By analyzing Equation 62 it is observed that the amplitude of forced oscillation is constant in time and between the elongation of the forced oscillation and the perturbing force there is a phase shift Moreover the oscillation frequency is equal to the frequency of the perturbing force This phenomenon can also be verified experimentally Resonance is a very important phenomenon that appears in the case of forced oscillation It consis
99. icator Change the values for the b and a and run the application again Save the application as First degree equation vi using the Save As option from the File pull down menu 18 Lab 1 Introduction Challenge 1 Adapt the application to implement Equation 4 to find the necessary time t it takes the material point to move to the x position 2 Modify the application to study the uniformly accelerated linear motion using Equation 5 which follows ll KEXytVy tt e 5 where a 1s the acceleration Graphical Programming As mentioned previously programming in LabVIEW is very different from programming in one of the classical text based programming languages A LabVIEW program is very similar to a logical scheme in which graphical blocks are used instead of text The Icons Graphical blocks in LabVIEW are called icons There are several types of icons such as Figure 1 17 including Icons associated with objects from the panel which allow only data input or output in from the program Icons associated with the functions which allow the application of simple or complex operations to the data Icons associated with subVIs which offer the possibility to modulate and encapsulate the programs as with the procedures in the classical programming languages Express icons which are complex superior level VIs that include functions or other inferior level VIs Express VIs are very useful to non pr
100. igure 1 22 Code included inside the structure will be repeated N times where N is the finite terminal loop counter input and 7 is the loop index terminal which counts the number of iterations that have been executed output terminal The For loop is indexed so all output data from the loop is stored as an indexed array Figure 1 22 The For loop The While Loop The repetitive structure While is an infinite and non indexed structure Figure 1 23 Code that 1s included inside the While sequence will be repeated until the fulfillment of the stopping condition The stopping condition logic may be one of the following m stop if true the execution of the loop stops if the condition becomes true m continue if true the execution of the loop is ended when the condition becomes false The While loop is non indexed therefore only values obtained at the execution of the last iteration are memorized Numeric ae eles Figure 1 23 The While loop Lab 1 Introduction 23 The Case Structure The Case structure is a decisional structure that can work in two ways Figure 1 24 1 Similar to the If decisional structure from classical programming languages if the structure selector receives Boolean values 2 Similar to the Case decisional structure from classical programming languages if the structure selector receives numeric integer values or controls such as Ring or Enum The Case struc
101. ineering Workbench is a powerful and flexible instrumentation and analysis software system LabVIEW has been widely adopted throughout industry academia and research labs as the standard for data acquisition and instrument control software A measurement instrument built using the computer is called a Virtual Instrument VI Figure 1 2 LabVIEW s intuitive user interface makes writing and using a Virtual Instrument easy and logical File Edit Operate Tools Browse Window Help o gt A S u 13pt Application Font Iodide Harmonic Distortion Analyzer Demo Exported time signal iinput signal o Input Signal m Analysis Results gt Frequency in Hz j 1234 890 Amplitude 311 000000 Noise bitYolt 20 16 12 6 4 0 ay ts 10 u at 60Hz ighest harmonic limited by yquist to 20 Highest harmonic Fs Hz Block size ibs p gt 451200 41024 advance d searc h approx fund freq optional 1 00 search of Fsampl 5 E a 1 1 1 1 1 po 0 5000 10000 15000 20000Hz 25000 aZ Figure 1 2 A simple Virtual Instrument VI Advanced Harmonic Analyzer Graphical Programming GQ LabVIEW departs from the sequential nature of traditional programming languages and instead uses a graphical programming language called G In a G programming environment the program is embodied in a front panel that sits on top of a graphical block diagram which compiles into m
102. is realized by using the characteristic equation attached to it r o 0 28 The solutions of the characteristic equation Equation 28 are r tiO 29 Using the solution of the characteristic equation the solution of the equation describing the free harmonic oscillatory movement Equation 27 is Xu Ce aCe 30 Equation 30 can be written using the formula e cosa isina as follows Xg C C cos t C iC sin t 31 If we note C C B and C iC D and we give B as forced factor Equation 31 becomes D XQ af cos O t a sin oy 32 The notation is D B ctgg cos sing Equation 32 becomes cos Xlr a si wt s n COS of 33 By using the trigonometric formulae and by noting B sing A Equation 33 can be written as follows x Asin a t g 34 where the constants A movement amplitude and initial phase of movement are determined in initial conditions The measure x t is called motion elongation The amplitude is the maximum elongation of the motion The initial phase indicates the initial position of the body with a mass m towards the equilibrium position 120 Lab 5 The Study of Vibration Besides the measures already discussed the oscillatory motion is also characterized by both the oscillation period and the oscillation frequency The proper oscillation period represents the time necessary for a complete oscillation The expression of the proper peri
103. l see Figure 1 11 The color and shape of connecting wires differ based on the data type of the data source Figure 1 19 presents some data types and some connecting wires used in LabVIEW ST a Orange floating point Blue integer om l c Figure 1 19 Data types and the wires associated with them in LabVIEW The Data Flow LabVIEW is a programming language based on data flow that goes from left controls to right indicators Execution of each program node is conditioned by the node receiving all data from its input terminals After the node is executed the Lab 1 Introduction 21 data will be found at the output terminals of the node The data flow in a LabVIEW program is presented in Figure 1 20 Figure 1 20 Data flow in LabVIEW Programming Structures Very much as in the classical programming languages LabVIEW offers operators for repetitive decisional and sequential programming structures The most well known repetitive programming structures are For and While and decisional structures are If and Case Programming structures are found in the Structures sub palette Figure 1 21 Case Structure Flat Sequence E Diagram Disa Conditional Di Feedback Node VAR LOCAL GLOG Shared Variable Local variable Global Variable CAN Ou Decorations Figure 1 21 Structures sub palette 22 Lab 1 Introduction The For Loop For is a repetitive structure that is finite and indexed F
104. l of the labs is to provide students with a general background in taking measurements for scientific and engineering applications The LabVIEW programs called virtual instruments or VIs that accompany the labs allow the students to take measurements without learning a new complex tool but they do not shelter students from the need to understand fundamental concepts nor will they prevent errors that can occur with particular measurements These lab exercises require the students to write or only run simple LabVIEW programs Using these simple introductory exercises the students will see how easy it is to program in LabVIEW and they will learn the first steps to building and using simple computer based instruments Introduction The labs are organized into subject matter areas each containing introductory sections entitled Instructor s Notes Goal Required Components and Background These sections serve as a preview of the material students are expected to learn in the labs along with providing the information they will need to complete the labs If students have done some programming even very simple programming before performing these labs they will get more out of writing their first LabVIEW program If students have had no previous programming experience LabVIEW can provide a very good introduction to programming Visualizing the operation of a program graphically is easier for most people than looking at lines of textual code
105. law as follows R 40 81 I 0 54 For VPS safety it is recommended to use a bigger resistance In this exercise we use a 27 Q resistor In order to implement the PID algorithm for temperature control the following steps must be taken 1 Build the testing circuit shown in Figure 6 21 and Figure 6 22 2 Start the NI LabVIEW 2010 software and modify the application built in the first exercise as in Figure 6 23 and Figure 6 24 NATIONAL Dili iT mi sy i sehen ab es nba ah we bial We aea hoo ps A ELVIS I SERES S so ciii EG z z a Daie aan aaan a aae nea ieia PROTOTYPING BOARD L KUR a E PAE Re S 3 fared sega A ore nd Coe ade eae eee eee ae LLI a aa Pra er E Bref aires aana a reee ek Mente Toucan Sees a If babies Sw are Seats Se EE E OA A a AE D LI eomermemz fee ee Pw et aa sg s LLI Figure 6 21 The circuit for PID temperature control in NI Multisim Lab 6 Introduction to Control 161 vouw oe wll oe HEE EE ve eee ue a se a ws se lawa uwew ve oe ijee wa FE PMI re Es tz To DMM fee ee es sawn t Heater aT R 27Q sage HE LM335 Malls waar lied Or Figure 6 22 The circuit for PID temperature control on NI ELVIS ge ye ey ole es File Edit View Project Operate Tools Window Help gt Device Name autotune F autotuning Set Point WW J Dev4 v C
106. le Power fal Supplies m Figure 6 24 The Diagram of the temperature control In the Panel 3 Replace the Actual speed gauge control with thermometer control from Modern Numeric control palette and rename it Actual Temperature 4 Rescale the set point to appropriate values e g 80 C Double click on the maximum value of the scale and write 80 and then click outside In the Diagram 5 Place the temperature conversion VI called Temperature VI built in Chapter 1 and create a constant for the Scale select input Chose the Celsius option 6 Keep the PID output at the 0 100 range The conversion of the PID output to voltage applied to the heater by the VPS is based on the following equation i CO 11V UV ol 100 82 7 Set the PID coefficients to the following values K 21 T 0 8 and Tp 0 15 and run the application Notice the results 8 Press the autotuning button and follow the steps to obtain the optimum PID coefficients 9 Let the heater cool down and then restart the application Lab 6 Introduction to Control 163 Challenge 1 Using both setups described in this chapter try to apply the Ziegler and Nichols tuning methods to determine the PID coefficients 2 Inthe same configuration using the autotuning application calculate the optimum PID coefficients Compare the results 3 Control the systems using the P PI and PID algorithms and compare their performances 4 Find the PID coefficients u
107. lines AOO and AO1 belong to the data acquisition board Function Generator lines FGEN SYNC AM and FM belong to the Function Generator board 6 Power lines for 15 V 15 V 5 V belong to the workstation 7 DIO lines 0 to 23 belong to the data acquisition board PFI lines for counter and synchronization of DIO tasks belong to the data acquisition board The NI ELVIS I workstation is populated on its left side with BNC type I O terminals for the Function Generator FGEN the IOOMS sec Oscilloscope Scope and digital multimeter DMM On the right side the workstation has two knobs for manual voltage setting in 0 12 V or 12 0 V and another set of two knobs for the Function Generator frequency and amplitude settings 4 Lab 1 Introduction Goal This lab introduces the idea of a computer based instrument through building a simple instrument using the NI ELVIS II workstation and controlling it with a LabVIEW program The lab also gives a short tutorial for LabVIEW programming Required Components Required software includes LabVIEW 2010 NI ELVIS II software Required soft front panels SFPs include Digital multimeter DMM Digital voltmeter DMM V Digital ammeter DMM A Required components include 5 6kQ resistor R R2 and R I M335 temperature sensor Lab 1 Introduction 5 Introduction to Graphical Computer Programming LabVIEW LabVIEW or Laboratory Virtual Instrument Eng
108. ll remain see Figure 6 3 The offset is a function of the proportional gain K and the process gain Process Variable AZ 9 30 Rue PV Setpoint Setpoint he d 10 00 15 125 offset 10 ee ee EP EP ee ee ee en ee ee eee eee eee ey a JEPE a SA A GE E SEA TE A EE Se EES a aa a 75 ya A Ed 5 254 M l 0 85 Time Figure 6 3 The Proportional control Lab 6 Introduction to Control 143 The effect of K increasing over the offset is shown in Figure 6 4 One can see that the offset decreases as K increases But increasing the value of K can make the controller unstable In addition from Figure 6 4 one can see that the controller reaches the set point faster PV Setpoint 10 Amplitude Lad MN wW vn t y co wW SS SS e T Setpoint PV Kp 5 AN PV Kp 10 PV Kp 20 Orlicccpeceegesccgeecepuccepeccaqeeecguccegeccegeceequseugersegeeeeqeveeqeteegeatey 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Time Figure 6 4 The effect of K increasing over the offset Integral The integral term I term is defined by Equation 71 u t K e z dz 71 0 If the error is not zero the summation of this integral is proportional to both the error s magnitude and its duration So summing the error over time the control signal becomes larger forcing the system to react in the direction of eliminating the residual offset that occurs with just a proportional controller Th
109. lock Diagram File Edit View Project Operate Tools Window Help Filename2 b 6a E af Read From Measurement File2 Split Signals Convert from Dynamic Data3 Signals e Array Max amp Min p B Convert from Dynamic Data4 p Ea Solar Cell I V characteristic Filename 3 a Read From Measurement File Split Signals Figure 7 14 Panel and Diagram of the series resistance application 4 As for the method used to determine the series resistance two characteristics are necessary two identical lines are made for the program that permit the data to be read in turn and to be displayed on an X Y graph indicator 5 From each signal the current is extracted as well as the voltage To determine the short circuit current the maximum is extracted from the current vector The maximum value of the vector 1s a good approximation of the short circuit current because the portion of the I V characteristic for the interval 0 0 1V is parallel with the Ox axis To obtain this the icon Array Max amp Min is used 6 To obtain the necessary values in Equation 87 the following procedure will be put into practice the short circuit current of the characteristic for the lower illumination level of the characteristic will be divided by two and by using reverse interpolation changing the axis between them the value of the voltage will be found for this characteristic The value I 2 will be subtra
110. longation equation can be written as 124 Lab 5 The Study of Vibration XW e Ce Ce unde W 0 0 47 By using the Euler formulae see the undamped oscillatory motion Equation 47 the elongation equation becomes x A sin a t unde A Ae 48 The elongation and amplitude trajectory is shown in Figure 5 4 It can be observed that the amplitude becomes a monotonically decreasing function of time If the time tends to infinity then the elongation tends to zero In this case the body oscillates around the equilibrium position with smaller and smaller amplitude In order to characterize the decreasing of the amplitude the measure called logarithmic decrement is introduced By definition the logarithmic decrement is a natural logarithm from the ratio of two consecutive amplitudes See Equation 49 which follows A Ae A In In gy Ine T 49 Avr 0 20 017 015 012 010 Mand 0 05 0 03 a amp 0 03 0 05 0 10 0 13 0 15 0 18 Figure 5 4 Representation of elongation and amplitude in the case of low damping Another characteristic measure of damped harmonic motion is the relaxation time which is defined as the time in which the mechanical energy drops e times as in Equation 50 l kA 2 o Ew g 08 oot l ii Eis Skea 20 pP 50 Lab 5 The Study of Vibration 125 The experimental setup consists of see Figure 5 5 the follo
111. lp File Edit View Project Operate Tools Window 3 2 2 Ln se Appicaion on ora gt JA a n F e ballot 15pt ad Scale select Temperature Scale Ol Kelvin 312159 ik 4 mW b 4 mW p Figure 1 50 The Panel and Diagram for Temperature measurements VI h Save the VI as Temperature measurements vi i Run the application Change Scale select value and look at the Temperature and Scale indicators 38 Lab 1 Introduction Exercise 1 3 Using the For and While loops Repetitive loops are very common programming techniques The For and While loops are used in LabVIEW just as in text based programming languages Build an application that makes a finite number of temperature measurements and gives a graphical representation of the temperature values Then change the application to monitor the temperature until a Stop button is pressed The time interval between two measurements can be varied using a control ex 1s Background The finite repetitive structure is called a For loop and the infinite repetitive structure is called a While loop Both structures have an index which 1s a variable that keeps track of the number of iterations that the loop executes The For loop has a Terminal Count control which indicates the number of iterations that need to be executed The While loop is stopped by a conditional Boolean terminal A graph indicator will be used to give a graphical display for temperature
112. ls for output range and PID gains inputs 11 To increase the performance of the controller a filter is applied to the feedback measurements This filter is applied using the PID Control Input Filter VI from Function Control Design amp Simulation PID 12 To control the voltage applied to the DC motor the NI ELVISmx Variable Power Supply express VI from Function Measurement I O NI ELVISmx is used 152 Lab 6 Introduction to Control 13 14 15 16 17 3 PID Control Speed vi vi Block Diagram e File Edit View Project Operate Tools Window Help PID Control Input Filter vi i000 Bes b status Sw gt error out Time Interval Wait Until Next ms Multiple EHA Figure 6 11 The PID Control Speed Diagram In order to convert the measured voltage U V generated by the tachometer into the motor speed v RPM Equation 75 is used U V 1000 E a Because the DC motor has its moving start point near 2 1 V we set the minimum voltage of the controller that is applied to the DC motor at 2 2 V We also limited the upper values at 4 4 V which means that the maximum speed of the motor will be approximately 2500 RPM In order to increase the controller resolution we use the 0 100 range for the controller output CO 2 after which the conversion in voltage that is applied to the motor Uo V is made These features are implemented using Equation 76 Co 2
113. lumn contains links to other local or Web help type files and to the very useful application Find Examples which offers a set of LabVIEW example programs Applications that are built in LabVIEW have the extension VI VI stands for Virtual Instrument the basic element of graphical programming LabVIEW version 8 0 introduced the notion of projects to allow for better management of VIs by executing tasks belonging to the same application 8 Lab 1 Introduction VI Panel and Diagram When creating a new VI is created in LabVIEW two windows are opened the Panel and the Diagram Figure 1 5 The Panel represents the user interface This window enables the introduction of indicators and controls in the program as well as the visualization of the results given by the running of the program The default color of the Panel is gray but it can be changed by the programmer The Diagram represents the source code of the application In LabVIEW instructions and commands are called functions The standard color of the Diagram is white Ngee Oe eee ee Untitled 1 Block Diagra Untitled 1 Block Diagram File Edit View Project Operate Tools Window Help Figure 1 5 The Panel and the Diagram of a VI The Controls Palette Input data or input variables are introduced in the program by using the so called controls while output data or output variables are retrieved from the program and display
114. me is obtained By using the bundle function the zero offset signal is built as a function of relative time By using Peak Detector vi from Function Signal Processing Signal Operation the maximum amplitudes are determined for each oscillation of the system The envelope curve of the signal is obtained by tracing the fitting curve among these points A number of consecutive peaks N V 25 is extracted consecutive maximum amplitudes with the function Index Array within a For loop Figure 5 7 The logarithmic decrement A is determined by using Equation 49 and by calculating the mean of the results obtained The damping coefficient 0 can also be determined using Equation 49 and from Equation 50 the relaxing time t is determined By multiplying the Location output of the Peak Detector vi with the time interval between data points in the waveform dt the positions in relative time are obtained for the maximum amplitudes of the signal The envelope curve of 128 Lab 5 The Study of Vibration the signal is found by graphically representing the maximum amplitudes function of the positions obtained black curve on the Vibration Graph from Figure 5 6 12 In the Panel fix the values for Horizontal and Trigger controls as shown in Figure 5 6 13 Power on the NI ELVIS II system and the prototyping board 14 Run the application and manually give an elastic impulse to the lamella 15 Visualize the values see Figure 5 6 Lab
115. measurements obtained must be repeatable 176 Lab 7 The Photovoltaic Characterization The number of points on the characteristic must be large in order to facilitate a fitting in good conditions The parameters of the solar cells can be obtained by fitting the characteristic The additional resistances introduced in the circuit must be reduced to the maximum when the circuit is realized The same environmental conditions must be kept when the measurements are performed Using the facilities of the fast prototyping board and the tools of NI ELVIS the requirements listed can be satisfied if the capacitor or the MOSFET is used for raising the I V characteristic of the solar cell The MOSFET was chosen because the circuit required is much simpler even if it has two minor disadvantages namely that it is a little slower and a smaller number of points can be obtained on the characteristic in comparison with what is obtained with the capacitor To practically realize the experiment on the prototyping board of the NI ELVIS the mounting presented in Figure 7 8 must be made It is relatively simple to make and will be used for the entire set of experiments 1 Build the setup shown in Figure 7 8 The parts are labeled as follows The monocristalline Si solar cell 0 5V 400 mA b The halogen light bulb of 35 W fed from a source of 12 V and 4 A and mounted on a frame that permits the variation of the distance between the light bulb and
116. mounting realized 1s complex and will be used for the entire set of experiments to test the relay 1 Build the setup shown in Figure 4 6 using the following elements a Electromagnetic relay of dc 12 V Chansin b The resistance of 5 19 Q necessary to fix the current in the circuit 1A allowing us to measure the contact resistance The resistance used has to be a power resistance at least 5 W so that it won t change its value during measurements because of the thermal effect thus reducing the measuring error c The transistors needed for the relay control from the DIO ports of the NI ELVIS d The connection to the ammeter to measure the current in the circuit when the relay is closed 98 Lab 4 Interfacing Actuators Figure 4 6 The setup of relay testing e The connection to the oscilloscope NI ELVIS via two BNC cables For this part of the experiment only one channel is used to measure the voltage f The measured resistance of the contact voltage 2 Using Equation 25 we can find the value of the contact resistance R 25 3 The electronic circuit was realized in Multisim as well for an easier implementation see Figure 4 7 10 11 12 13 Lab 4 Interfacing Actuators 99 relay circuit Multisim relay circuit Bi 7 Loe es Fi File Edit View Place MCU Simulate Transfer Tools Reports Options Window Help l
117. n button is not pressed the selection of tools is made manually by pressing the button corresponding to the desired tool or by repeatedly pressing the Tab key If the Automatic tool selection button is pressed the selection is made automatically depending on the cursor s position relative to the objects on the screen 12 Lab 1 Introduction Functions Programming Measurement O Instrument O Vision and Motion Mathematics Signal Processing Data Communication Connectivity Control Design amp Simulation SignalExpress Express 3a Input F Gi Sig Manip Addons F Favorites User Libraries Select a VI NAT Robotics RF Communications Change Visible Palettes Figure 1 10 The Functions palette es cl Automatic tool selection ih Operating tool Editing positioning and resizing tool Text editing tool Connecting tool Samples inserting tool Figure 1 11 Tools palette Lab 1 Introduction 13 Aligning Distributing and Resizing Objects In order to create a friendly interface the objects from the panel must be aligned and uniformly distributed This can be achieved manually but it requires very meticulous and time consuming operations In addition certain objects must be dimensioned to the same size Such operations can be done with the help of the buttons situated on the instrument s toolbox TEY Aligning objects Distributing objects Resizing objects
118. ng the solar cells performance are short circuit current Zc open circuit voltage Voc maximum power Pmax fill factor FF efficiency and internal parameters These parameters are briefly described in thefollowing list The open circuit voltage V is the voltage generated by the solar cell when the current is zero high impedance J 0 This quantity is related to the bandgap of the semiconductor used T 1 v AE of 83 q L where k is the Boltzmann constant T is the temperature of the solar cell q represents the elementary load of the electron Zp is the photogenerated current of the cell and Z is the reverse saturation current Lab 7 The Photovoltaic Characterization 169 The short circuit current is the current generated by the solar cell if the voltage across the device is V 0 The current increases proportionally to the illumination level and the surface of the cell For the current the current density is also used denoted by J representing the ratio between the current generated by the cell and its area The maximum power Pmax produced by the device is reached when the product I V is maximum This is shown graphically in Figure 7 2 where the position of the maximum power point represents the largest area of the rectangle shown The fill factor FF corresponds to the ratio of the maxim power that can be generated by the solar cell to the product of Voe Ise see Equation 84 This
119. nown also as the Three Term Controller The three terms are Proportional Integral and Derivative The PID controller is described by Equation 70 u K elt K felryar K Lolo 70 0 where u t is the output of the controller also known as the control signal e t represents the tracking error and K K and Kg are the PID coefficients The tracking error is calculated as the difference between the set point SP the desired value and the process variable PV the system output value The diagram of this algorithm is shown in Figure 6 2 142 Lab 6 Introduction to Control Process variable Figure 6 2 The PID diagram Interpreting the Terms Proportional In order to understand the terms effect only one at a time will be considered In the first step the K and K4 have to be maintained at zero So from Equation 70 only u t K e t remains meaning that the control is proportional to the current error value The proportional control can be accredited with the present term The proportional term P term is sometimes called gain and is sometimes noted as Ke If the error is high the control signal is high if the error is small the control signal is small If the system is closer to the set point the response of the controller is negligible Thus if the system drifts a bit from the set point the control does almost nothing to bring it back Using the proportional control an offset between the SP and PV wi
120. od 1s given by the formula T ae 2r 35 O k The oscillation frequency can be calculated by the following equation V 270 2r JE 36 T m By deriving the function of t the elongation given by Equation 34 the oscillation velocity is determined the measure representing the velocity at which a body of m mass approaches or gets away from the equilibrium position v x Aw cosl t o 37 Because the oscillation can also be defined as the phenomenon during which energy is periodically transformed from one state to another the total mechanical energy of an oscillator can be calculated as the sum of the kinetic energy and the potential energy 2 2 E E E _ mA o COS a F 9 rt m A sin a 9 38 2 2 2 2 2 2 me cos w t g sin t p a As can be observed from Equation 38 the total mechanical energy of the oscillator is conserved as is shown in Figure 5 2 Lab 5 The Study of Vibration 121 Figure 5 2 Total mechanical energy of the ideal harmonic oscillator References R V Dukkipati amp J Srinivas 2004 Textbook of Mechanical Vibrations Prentice Hall of India Pvt Ltd New Delhi India J S Rao amp K Gupta 1999 Introductory Course on Theory and Practice of Mechanical Vibrations New Age International Publishers New Delhi India C W de Silva 2007 Vibration Monitoring Testing and Instrumentation Taylor amp Francis CRC Press Boca Raton Fl
121. ogrammers because they include a lot of functionality under one icon The icons of these VIs have a blue background and can be enlarged Express VIs can be configured either at the first call or by double clicking on them Configuration is done by selecting parameters For example in the case of the express VI for spectral analysis one can select the type of analysis that needs to be made the type of window to be used and so forth Lab 1 Introduction 19 Icons Controls Indicators Pf By the terminal Icons associated with DE type the objects from the panel DE By the data type Icons associated with the functions Icons associated with subVIs Express icons Simulate Signal Figure 1 17 Icon types Visualization in the Diagram of a VI icon that is associated with a subVI can be made in several ways Figure 1 18 as icon limited as icon extended or as icon resized extended The icon background is yellow for subVIs and blue for express VIs 20 Lab 1 Introduction Icon Extended Resized Icon Extended Resized default default F F bd Simulate Signal F F F F F F F 7 7 F fad Sine Waveform wi L Simulate Signal error out Sine Waveform vi signal ouk Simulate Signal Figure 1 18 Icons visualization modes Connecting the Icons Data transfer from one icon to another is made by using connecting wires The connection is made using the connecting too
122. ooo S r m E zra rin Shane an EREE epee pp a z THE Et a a E j l i i Soe J if Ll x r a oS am vue sue k Len J m ET a i am E al au Hai Pee Ls F JRF m H i maz Tk 1k c eo Tee a ie k r r e Ba J 1 i 1 stat Figure 4 14 The Multisim schemata for stepper motor control Lab 4 Interfacing Actuators 109 File Edit View E Operate Tools Window 2 n Device Name i Dew No of Steps Delay 3 Stepper Full Step vi Block Diagram File Edit View Project Operate Tools Window Help SE me epson Foe oe I No of Steps Delay f a Elapsed steps NI ELVISmx i Digital Writer2 error out mi NI ELVISmx qm mi Digital Writer NI ELVISmx b errorin b errorin in Variable Power NIELS Variable Power Supplies Figure 4 15 Panel and Diagram of the full step control application 6 Place in the Diagram the NI ELVISmx Digital Writer express VI to realize the control of the stepper motor The control is realized using the first four DIO ports of the NI ELVIS board The control sequence of the stepper engine is transformed from base 2 to base 10 see Table 4 1 Table 4 1 110 Lab 4 Interfacing Actuators 7 To avoid a loss of steps and a repositioning on the motor shaft at a new initialization the icon Rotate string is used 8 Create the numerical indicator for elapsed steps 9 Power on the NI EL
123. open circuit voltage is raised proportionally to the number of solar cells bound in series see Figure 7 4 In the given example two cells are bound in series The open circuit voltage is doubled see the red curve when the two twin solar cells are bound in series and the short circuit current remains the same Solar Cell I V I V characteristics Series Solar Cell I V va 0 32 0 3 as re a E oe a a ae a a i ae ae a E a ae E T 9175 a aa s een D CR a a a a a Ss eee a a ie zoe a OS ee es A a a i E es i j I 1 I i 0 0 2 0 4 0 6 08 1 1 2 Voltage V Figure 7 4 The I V characteristic for a cell blue and the characteristic for two cells bound in series red More cells are bound in series and the short circuit current is raised proportionally with the number of cells see Figure 7 5 In the given example two solar cells are bound in parallel The short circuit debited by the system is doubled see the red curve when the two twin solar cells are bound in parallel and the open circuit voltage remains the same Solar Cell I V vas I V characteristics Paralel Solar Cell I V 7 0 32 0 3 a ee a a we i So a aa C a 02 C ae a a Z 9 475 ae a a S 0 125 oO To S a a a ee De pt E NS i i E E EEN as a ae Se Voltage V Figure 7 5 The I V characteristic for one cell blue and the characteristic for two cells bound in parallel red Lab 7 The Photovoltaic Characterization 173
124. orida W T Thomson 2003 Theory of Vibration with Applications Nelson Thomes Ltd Cheltenham UK S Timoshenko 1937 Vibration Problems in Engineering Van Nostrand New York 122 Lab 5 The Study of Vibration Exercise 5 1 Study of damped harmonic oscillatory movement Given that the undamped harmonic oscillations represent ideal cases the emphasis in this section will be on damped harmonic oscillations In the real case due to friction from the oscillatory system the motion amplitude continuously drops de Silva Rao et al The damping can be either external 1 e friction takes place between the system elements and the environment or internal 1 e friction takes place within the system The most widely encountered case in practice is emphasized here namely when the friction force is proportional to the velocity See Equation 39 which follows F px 39 In this case Equation 26 can be written as mepa tien 40 If Equation 40 is divided by m the following is obtained mx 20x x 0 41 where 20 p m and is called the damping coefficient By attaching the equation characteristic to the differential equation with the constant coefficient we obtain r 26r 0 42 Equation 42 has the solutions n t f o 43 By using the solutions obtained for the characteristic equation attached to Equation 41 the following solutions are obtained for the latter n g am A ga 44 Lab
125. ormula Node structure The VI Icon and Connector Any LabVIEW VI can be used as a subVI in another LabVIEW application SubVIs resemble procedures from classical programming languages The major difference between the classical procedure and a subVI is that the subVI can be used as an independent application that does not need to include a call from another application For a VI to be used as a subVI the VI needs to have its own Icon and Connector The icon is the VI graphical representation Figure 1 28 Each LabVIEW VI has a default icon and connector associated with it The user chooses whether he or she wants to customize these or not The VI icon is displayed in the upper right corner of the VI Panel or the VI Diagram When using the VI as a subVI its icon will be visible in the Diagram Lab 1 Introduction 25 Figure 1 28 The icon of a VI The connector represents VI inputs and outputs using terminals Figure 1 29 The number of terminals in a connector depends on the number of input controls and output indicators the VI has The Execution of a VI Execution of an application is started by clicking the Run button from the toolbox or from the menu Operate Run The application will execute one time for each click on the Run button VI Properties Edit Icon Show Icon Find All Instances ermina HEUHA H fs em HIE JESRUAHER revere kii Properties E EHER eS EL Edit Icon HHEYH EHR EE Show Connec
126. ors 8 Using a pyranometer such as the Daystar Solar Meter and a light source with adjustable distance from the sensor its response can be calibrated Figure 3 12 4 Oscilloscope NI ELVISmx Cursors Settings Cursors On Display Measurements V CH 0 12 Basic Settings Advanced Se bal e ES Channel 0 Settings o Source AIO X 7 Enabled Scale Vertical Volts Div Position Div 2 VY iV x o Timebase Trigger Type Time Div 20us Instrument Control Run E Stop Log Help Ceme ia mi we l 7 Source Level V J Chan 0 Source 0 2 4 Horizontal Position U 50 Channel 1 Settings w Source AIO X Enabled Scale Vertical Volts Div Position Div J WZ 1V o Slope Acquisition Mode Run Continuously X Figure 3 12 The TSL230R sensor on NI ELVIS Il Lab 3 Interfacing Basic Sensors TI Exercise 3 2 Using the Mx2125 accelerometer The goal of the first exercise with the accelerometer is to understand the functionality of the Mx2125 This exercise focuses on visualizing the output signals of the sensor and the signal modification when the accelerometer is tilted 1 Implement the testing circuit shown in Figure 3 8 on the NI ELVIS II prototyping board 2 Power on the NI ELVIS II system and the prototyping board Start the NI EL
127. perature Monitoring vi Block Diagram Temperature File Edit View Project Operate Tools Window Help gt a Ll elieelecler 2 Figure 1 61 The Panel and Diagram of the Real Temperature Monitoring VI oc ute fabs A m Lab 1 Introduction 49 Challenge 1 Modify the Temperature Monitoring vi to offer the option of choosing the temperature scale 2 Build the circuit as shown in Figure 1 62 and measure the voltage Notice that the voltage is different from that in the circuit shown in Figure 1 58b Why Find the new relation between the measured voltage and Vcc and R R2 and R3 Find the current value for the studied circuits using Ohm s law gt 16 o DMM COM Figure 1 62 The modified Voltage divider 3 Modify the Voltage divider circuit to allow measurement of the current using the DMM Figure 1 63 To DMM COM Figure 1 63 The current measuring circuit 50 Lab 1 Introduction Notes Lab 2 Introduction to Testing Measurement and Data Acquisition 51 Lab 2 Introduction to Testing Measurement and Data Acquisition Instructor s Notes The lab exercises in this chapter introduce students to LabVIEW based systems but do not teach them all about LabVIEW programming Primarily LabVIEW is used as an instructor s aid for developing lab exercises and lab setups that introduce students to testing measurement and data acquisition The overall goa
128. perature on the Celsius scale Conversion of the voltage value in Celsius temperature units can be done using Equation 6 which follows t C U V a b 6 Building the LabVIEW VIs The Voltage vi Let us simulate the measurement of a voltage value that is an integer number in the range from 2 9 to 3 2 We will use the Random Number Generator 0 1 function which generates random numbers in the interval from 0 to 1 If we multiply the generated random number by 0 3 and then add 2 9 the resulting value will be an integer number in the interval from 2 9 to 3 2 3 Voltage Read vi Front Panel Co e 3 Voltage Read vi Block Diagram File Edit View Project Operate Tools Window File Edit View Project Operate Tools Window fanal gt OLTA u 15pt Application Font niles CORES ICSE A Random Number 0 1 Figure 1 33 The Panel and Diagram for the Voltage vi The following steps must be completed in order to build the Voltage vi Panel and Diagram Figure 1 33 a Open a Blank VI from the start panel of the LabVIEW application l j Lab 1 Introduction 29 Open the Controls Palette from the pull down menu select View or press the right mouse button in the Panel window Select a Meter indicator from Express Numeric Indicators place it on the Panel and name it Voltage Activate the Diagram window by pressing the left mouse button inside the Diagram window or select the option Show
129. perform this function in our case LabVIEW or NI ELVIS instruments do this job inside the computer system Data distribution is the process of supplying of measurement data to the target object If there are multiple outputs several target instruments may possibly be present such as a series of control devices in a process control In some cases 54 Lab 2 Introduction to Testing Measurement and Data Acquisition these targets can be the direct educational results of measurements and process control Data pal Data ull Data Acquisitig if Processin Distributi Wa Wa Wa Figure 2 1 Measuring system structure The entire NI ELVIS system is built on top of National Instruments s LabVIEW software and hardware and has three main components as shown in Figure 2 2 and described in the following list ELVIS software on the PC provides a graphical interface for several electronic instruments These instruments are discussed in detail throughout the remainder of this guide The PC connects to the bench top workstation through the data acquisition board located inside the NI ELVIS II system This board has both analog and digital input and output lines The bench top workstation provides electrical connections for the user to interface with circuits These provide inputs and outputs for the virtual instrumentation provided by the NI ELVIS software There is a prototyping board breadboard on the top of the workstation with sev
130. prototyping board breadboard sits on top of the workstation plugged into the NI ELVIS HI platform and offers hardware workspace for building circuits and interfacing experiments 2 NIELVIS II software which includes Soft front panel SFP instruments LabVIEW application programmatic interface API Multisim application programmatic interface API The APIs offer access to and custom control of NI ELVIS II workstation features using LabVIEW The bulk of the breadboard 1s made up of prototyping area holes that are not connected to the data acquisition board The prototyping board has four areas marked with the sign Connections inside these areas should be made based on vertical columns Connections in the three other sections of the prototyping board should be made horizontally Breadboard areas which are located at the far left and far right of the workstation are connected to the following instrumentation signal lines see Figure 1 1 1 Analog input signals AIO AI1 AI7 AISENSE and AIGND belong to the data acquisition board Lab 1 Introduction 3 NATIONAL Winstrumenrs NI ELVIS I NI ELVIS II SERIES W ree yyy 1 EA Figure 1 1 The NI ELVIS II platform 2 Programmable function I O lines PFIO to PFI11 belong to the data acquisition board and are used for synchronization of several instruments DMM Impedance Analyzers BASE DUT DUT belong to the DMM 4 Analog output
131. quency Function Generator to the value Actual Frequency determined by raising the previous frequency with the step of 0 184 between the values Start Frequency Hz and Stop Frequency Hz sustained Vibrations vi Po es File Edit View Project Operate Tools Window Help Study of vibrations Function Generator Configuration Oscilloscope Configuration Device Name Detected amplitude Dev4 0 0223599 Detected frequencie error out 22 724 status code AE 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 J 1 1 1 1 1 1 1 1 1 1 j 1 1 1 1 1 1 if 1 1 1 1 1 200 0m 400 0m 600 0m 800 0m IO LI LA LI LA LS Oe LB L9 20 21 22 293 2E Z5 26 27 29 29 30 31 327 33 34 35 36 37 38 39 49 Time w r Figure 5 11 The hammering phenomenon 4 Time Delay express vi is introduced between NI ELVISmx Function Generator express vi and NI ELVISmx Oscilloscope express vi The value for Delay Time s must be chosen so that the system vibrates with a new frequency given by the electromagnet ce Vibrationsvi sees File Edit View Project Operate Tools Window Help Study of Resonance Vibrations Vibrations Function Generator Configuration 1 510 1 500 1 490 TA E Actual Frequency Hz 10 044 i 1 j 1 j 1 j 1 1 300 0m 500 0m 700 0m 900 0m 1 0 Time Detected frequency Detected amplitude H 19 7475 0 0239587 error out as 45 Figure 5 12 The Resonance Vibration Panel
132. rcise 3 1 Using the TSL230R sensor This exercise about using the TSL230R LF focuses on understanding its functionality and configuration according to Table 3 1 and Table 3 2 We will use the NI ELVIS II virtual instruments F Digital Writer NI ELVISmx so fea Manual Pattern a 9 AAA ADAAN JUVURUUNM o Lines 7 6 5 4 x 2 1 0 Action Direction Toggle Rotate shift Left Instrument Control Run Stop Help Lm mt Figure 3 10 The Digital Writer instrument panel Build the testing circuit shown in Figure 3 3 Power on the NI ELVIS II system and the prototyping board Start the NI ELVIS II Instrument Launcher _ fae Launch the Digital Writer instrument Use this instrument to select the status of the SO S3 inputs Figure 3 10 5 Set the DIOO 3 lines according to Table 3 1 and Table 3 2 As one can see from Figure 3 10 the sensitivity is fixed at x value SO DIOO0 1 and S1 DIO1 0 and the frequency scaling is divided by 10 S2 gt DIO2 0 and S3 DIO3 1 6 Start the Oscilloscope instruments from the NI ELVIS II Instrument Launcher Choose the AIO option for Source and the 2 V value for Scale of the Channel 0 Settings 7 Notice the obtained values shown in Figure 3 11 Using the sensor responsitivity given in the manufacturer s datasheet the irradiance level can be determined TSL230 Datasheet 76 Lab 3 Interfacing Basic Sens
133. reases once with the sharp transition it has the tendency to amplify any high frequency noises If the system noise or the derivative gain 1s sufficiently large the system can become unstable Similar to the integral term the derivative term can be related to the proportional gain by K K T 74 P where T3 is the derivative time Lab 6 Introduction to Control 145 The effect of the derivative term is to decrease the time necessary for the controller to reach the set point Figure 6 6 This is obtained by slowing the rate of change of the controller output especially around the set point PV Setpoint Amplitude 4 Setpoint os PV Kd 0 001 2 PV Kd 0 002 PV Kd 0 004 75 Lf ec eee DENNEN DENEAN DOANEAN DENONA BONE Sm mereen semeren marenae samne saen 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Samples Figure 6 6 The effect of K increasing Combining the three terms good controller stability can be obtained The most frequently used combinations of these three terms are P PI PID and more rarely PD PID Tuning The PID controller is based on three coefficients Kp Ki and Kg as was shown previously The stability of the system depends on the selection of the coefficients The process of adjusting the PID coefficients to optimum values in order to obtain the desired control response represents the controller tuning There are many methods to find the coefficients
134. relays Figure 4 4 c The normally opened relays have a switch that remains open until excitation while the normally closed ones are closed until excitation Sullivan NO NC e a M S 5 a b c Figure 4 4 Electromagnetic relay types 94 Lab 4 Interfacing Actuators Stepper Motors The stepper motor converts the electric energy into mechanical energy Its functioning is realized by transforming a digital impulse train into a proportional movement of its axis As compared to standard DC motors stepper motors don t have a fluid functioning but instead consist of small steps taken one at a time The steps of the motor represent the angular motion of the rotor The number of steps 1s a controlled function of the command impulses applied to the phases of the motor Due to the univocity of the conversion impulses the number of steps associated with the memory of position stepper motors have become widely used devices in systems involving position adjustment Stepper motors can be divided into three major classes Permanent magnet there are many types unipolar bipolar and multiphase and they have two independent windings with or without center taps Variable reluctance motors these can have three or four windings Hybrid motors these are a combination of the first two types combining the advantages of both Unipolar motors are easily controlled The necessary stepping sequence can be generated by
135. rfacing Basic Sensors 81 EF AA vi wi Shock ana File Edit View Project Operate Tools Window Help n k pulse number 1 fe u period Channel 0 Eai NI ELVISmx pez ap Oscilloscope gt gt 8 2 gt ps j Channel 11 pulse duration p__ChannelO cee Device Name DE l T a duty cycle in Jazz f Trigger j Pulse Measurements vi Trigger 3 ELVIS Channel 0 stor out E EVIS Channe PTE a BD erorout oe fe cay Ee stop i Figure 3 16 The Memsic 2125 v1 vi diagram Place in the diagram the NI ELVISmx Oscilloscope express VI from Function Measurement I O NI ELVISmx Create controls for Channel 0 Channel 1 Device Name Horizontal Trigger and a graph indicator for visualizing the measured signals Place in the diagram the Pulse Measurements VI from Function Signal Processing Waveform Measurement Create indicators for period pulse duration and error out outputs With the pulse number 1 control one can set up the number of cycles for signal processing to determine the period T2 and the pulse duration T1 Using T2 and T1 values the acceleration values can be calculated using Equation 17 The implemented version of Equation 17 1s a g T1 T2 0 5 8 21 To implement Equation 21 the Divide Subtract and Multiply functions from Arithmetic amp Comparison Express Numeric are used Power on the NI ELVIS II system and the p
136. rgy by a process called photovoltaic conversion The cell is essentially a large area p n junction diode or rectifier made from two pieces of silicon that are fused together The general configuration of a simple cell and a challenging one is presented in Figure 7 1 The main part of a solar cell is represented by the p n junction which converts light into electrical power The contacts are realized from highly conductive metals The back contact covers the whole area of the cell and the front contact is realized with the shape of fingers For the more challenging cells an antireflective coating is added to these components with the purpose of reducing the reflection from the front surface S10 and Ta20O can be used as antireflective coatings their thickness being carefully chosen Kazmersk1 166 Lab 7 The Photovoltaic Characterization h depletition LA saan ma a b Figure 7 1 Schematic view of a PV cell which shows the basic semiconductor layers a and b Goal The purpose of this set of exercises 1s to study the behavior of some types of solar cells and mini solar panels using the NI ELVIS II platform The first goals of the lab exercises include the raising of the I V characteristic of the solar cell the determination of some solar cell parameters and investigating the variation of the short circuit current Is and open circuit voltage Voc function of illumination An additional goal is to study the behavior of the c
137. rison 190 Lab 7 The Photovoltaic Characterization Challenge 1 By modifying the program in Exercise 7 1 for raising the I V characteristic of the solar cell create a program that permits a The raising on the same graph of both the current voltage characteristic and the power voltage characteristic see Figure 7 19 et La 1 T re Solar Cell characteristics 024 024 1 I 1 01 0 2 0 3 0 4 0 5 0 6 Voltage V Figure 7 19 The l V and P V characteristics of the solar cell b Using as a possible example the interpolation from Exercise 7 2 determine the maximum power debited by the solar cell determining at the same time the current and the voltage corresponding to the maximum power point c With the results obtained in list item b and using Equation 84 create a program permitting the determination of the fill factor FF The short circuit current can be determined by extracting the maximum value from the current vector and the open circuit voltage Voc can be similarly extracted from the voltage vector 2 Realize an application that permits the determination of the ideality factor of the diode m Equation 92 which follows can be used to this purpose V oct 7 Vier 92 ne KT I q I sez The open circuit voltages Voc and Voc2 can be determined from the two I V characteristics raised at different illumination levels using the icon Array Max Lab 7 The Photovoltaic Characterization 1
138. rototyping board 82 Lab 3 Interfacing Basic Sensors 10 Run the application and visualize the signals Place the prototyping board in a horizontal position and notice the acceleration values 11 Tilt the prototyping board once every five degrees using the protractor and record the acceleration values in Table 3 3 Using the recorded values the sensor can be calibrated in angle units What kind of dependencies are obtained For more details consult the Memsic application notes MXD2125G amp M Application Notes An O0mx 007 Application Note Table 3 3 Dependence of acceleration versus angle Angle a Acceleration g ee Lab 3 Interfacing Basic Sensors 83 Exercise 3 4 Circular level using Mx2125 Based on the application built in Exercise 3 3 in this experiment a circular level will be developed 1 Start the LabVIEW software 2 Build the setup shown in Figure 3 17 as follows a Remove the mobile prototyping board from the U type holder shown in Exercise 3 3 and dispose of the holder b Leave the same connection between the mobile prototyping board and the NI ELVIS prototyping board Figure 3 17 The circular level setup 3 Start the NI LabVIEW software and modify the Memsic 2125 v1 vi as in Figure 3 18 and Figure 3 19 4 Inthe Panel the 2D Picture Horizontal Pointer Slide and Vertical Pointer Slide are used 84 10 11 Lab 3 Interfacing Basic Sensors In the Diagram the Draw Circl
139. s performing data acquisition As technology has progressed this type of process has been simplified and made more accurate versatile and reliable through the use of electronic equipment Equipment ranges from simple recorders to sophisticated computer systems Data acquisition products serve as a focal point in a system tying together a wide variety of products such as sensors that indicate temperature flow level or pressure Some common data acquisition terms are shown in the following list italics indicate how students will encounter these terms in the NI ELVIS II system Analog to digital converter ADC an electronic device that converts analog signals to an equivalent digital form The analog to digital converter is the heart of most data acquisition systems Like AIO to AI7 on the NI ELVIS II Prototyping Board Digital to analog converter D A an electronic component found in many data acquisition devices that produces an analog output signal Like Analog Outputs AOO and AO in the NI ELVIS II system Digital input output DIO refers to a type of data acquisition signal Digital I Os are discrete signals that represent one of two possible states These states may be on off high low 1 0 and so forth Digital I Os are also referred to as binary I O Like DIO 0 to DIO 23 in the NI ELVIS II system Differential input refers to the way a signal is wired to a data acquisition device Differential inputs have a uniqu
140. s on the arrow of the Case structure to see the options For activating the Fahrenheit option right click on the case structure border and select the Add Case After option the result should look like Figure 1 42 J Kelvin Default Celsius lt Fahrenheit Scale select f Figure 1 42 The case structure with Kelvin Celsius and Fahrenheit options Select the Kelvin option from the top of the case structure Select the Multiply function and a Numeric Constant from Express Arithmetic amp Comparison Express Numeric and place it into the Kelvin case structure Assign the numeric constant a value of 100 Extend the function palette using the arrows in the same manner as for Control palette Select a String Constant from Programming String Figure 1 43 and place it into the Kelvin case structure Write into String Constant the K value 34 Lab 1 Introduction J Functions Q Search gt Programming Measurement I O 1 Programming Instrument I O i String Se z b gt Vision and Motion m Mathematics fl of i Structures Array Cluster Clas Signal Processing 7 aq 5 Data Communication i A I St aS ring Connectivity Numeric Boolean String String Constant Control Design amp Simulation gt gt gt E gt shag SignalExpress gt h P ria Express Comparison Timing Dialog amp Use Eg bed A Eaton Ean l mt el Jat ue Eem tra E A A PE 5 es File YO Waveform Applica
141. s option allows visualization of the application s data flow values that travel through the connecting wires You can also use a Probe to visualize data in LabVIEW The Probe is an indicator of data type corresponding to the investigated wire connection The Probe is a method that allows for visualization of the data that passes through a wire during application execution Probe activation can be made either by using the probe insertion tool Probe Data Figure 1 32 or by pressing the right mouse button on the wire to be investigated and selecting the Probe option Lab 1 Introduction 21 List Errors displays the list of errors in the application fom Highlight Execution animated execution 7 Probe Data Probe insertion tool Set Clear Breakpoint application s execution breaking points insertion tool Figure 1 32 Buttons for LabVIEW application s execution 28 Lab 1 Introduction Exercise 1 2 Create and use a subVl When a certain task has been coded and will be used more than once in the same program or in other programs it is a good idea to save that code as a subVI Applications that use this subVI will be more easily understood Build an application that simulates reading of a voltage from a source and then converts the voltage into Celsius or another temperature unit Kelvin or Fahrenheit Background Let us consider that we have a temperature sensor that gives out voltage that is proportional with the tem
142. sed on Pulse Width Modulation PWM This technique means controlling the on time of a pulse wave The pulse wave is characterized by the period T amplitude 4 and the duty cycle DT see Figure 6 15 The period represents the time interval that verifies Equation 77 y t y t T 77 where y t is the signal wave The duty cycle DT represents the on time interval In general DT is expressed in percentages J Amplitude I I I l I I I l I I I l I I I l I I I l I I I l I I I l I I I l I I I l I I I l 0 0 02 004 006 008 0l 012 014 O16 O18 02 Samples Figure 6 15 The pulse wave parameters The PWM concept follows from the fact that the output of a system is switched quickly between fully on and fully off modulating the pulse width The frequency used in switching a system from on to off is between a few hundred Hz and a few hundred kHz Using PWM the power amount delivered to the system can be regulated at desired values The regulation is based on the fact that the average power delivered to the system is proportional to the modulation duty cycle Using passive filters the pulse waves can be smoothed in order to recover the average voltage value In order to obtain the average value of a pulse wave Equations 78 and 79 are used 156 Lab 6 Introduction to Control t T l a y t dt 78 I T DT y yoa 7 ve ll tdt fral dt T DT y 7 DT yn F T DT 79 T If Ymin 0 then the avera
143. shown in Figure 6 10 and Figure 6 11 43 PID Control Speed v1 vi Sago Ex File Edit View Project Operate Tools Window Help seen Device Name Set Point AN Dev4 Speed Actual Speed A error out 2105 07 status code z S fo z 1500 0 source w 1000 0 t x 500 0 output range l f 2 f aca i J e 00 00 22 4 100 00 proportional gain Kc a 0 057612 T i ime Ti min 0 031244 T output low integral time Ti min a PID Output Plot 0 AN 0 00 derivative time Td min 0 007811 5 07 4 54 4 04 Set Point RPM Actual Speed v 1000 au 30 800 1200 a Thy 4 E 800 1200 5 gt 3 04 gt f M 600 2 57 1600 400 1600 1 400 al 4 205 aem 1800 00 00 00 00 00 22 i y Time 2007 1800 X 9 70 ii 1000 000 Set Point Overrange Time Interval STOP ai 1000 996 595 Actual Speed In Range gi Figure 6 10 The PID Control Speed Pane 9 Place in the diagram the NI ELVISmx Digital Multimeter express VI from Function Measurement I O NI ELVISm x Right click on the Device Name input and choose the Create Control option Repeat the operation for the DC Voltage Input create a constant and choose the 60 V value 10 Place in the diagram the PID VI from Function Control Design amp Simulation PID In order to use this VI it is necessary to first install the NI LabVIEW PID and Fuzzy Logic Toolkit The PID VI implements Equation 70 Create the contro
144. sing of the I V characteristic and the data saving for a single state To realize the comparison of the data obtained a program structure is used see Figure 7 17 permitting the raising of the I V characteristics on the same graph The current voltage characteristic for one single cell is blue in color What can be observed In comparison with the red curve that represents the characteristic for two cells bound in series 1t can be said that the short circuit current is the same and the opencircuit voltage is twice as big For the binding in parallel the current rises two times with the voltage remaining the same An improvement in the program can be achieved by making the experiment for the determination of the series resistance an interpolation and numeric indicators can be created for the short circuit current as well as for the open voltage Lab 7 The Photovoltaic Characterization 187 BANANA A BANANA B BANANA C x BANANA D or 20 Vrms MAX Figure 7 16 The setup of solar mini panel characterization 4 Another application that can be realized with the mounting already made and with the software used for Exercise 7 2 is the determination of the series resistance and its variation when the cells are bound either in parallel or in series 5 It can be observed in Figure 7 18 that when the cells are bound in series the series resistance rises and when they are bound in parallel it decreases in comparison to the value
145. sing the control specification from the autotuning parameters cluster set on the values normal fast and slow Notice the differences in the system s response 164 Lab 6 Introduction to Control Notes Lab 7 The Photovoltaic Characterization 165 Lab 7 The Photovoltaic Characterization Instructor s Notes The term photovoltaic combines the Greek word for light photos with volt the name of the electromotive force unit the force that causes the motion of electrons The volt was named after the Italian physicist Alessandro Volta the inventor of the battery The photovoltaic effect consists of the occurrence of an electromotive voltage when the cell is illuminated The direct conversion of light into electric energy involves the photovoltaic effect where photon energy is used to change an electron from its ground state into an excited state Spanulescu Green Ideally there should be a one to one relationship between light and electric current each photon that strikes the device delivers its energy to an electron which in turn transports the energy to an electrical load connected to the terminals of the device The most important photovoltaic effects take place in the p n homojunction and heterojunction regions and at the metal semiconductor contact that being the place where a potential barrier and an electric field appear The solar cell has the capability to convert solar energy directly into electrical ene
146. t at full speed the output voltage of the tachometer is 18 V To measure this voltage it is necessary to set up the range of the DMM at 60 V In order to verify the system s functionality the following steps must be taken 150 Lab 6 Introduction to Control Pe 7 Build the testing circuit shown in Figure 6 8 Power on the NI ELVIS II system and the prototyping board Start the NI ELVIS II Instrument Launcher Launch the variable power supply VPS Use this instrument to set the voltage applied to the DC motor see Figure 6 9 Launch the digital multimeter DMM used for measuring the output voltage of the tachometer see Figure 6 9 Modify the voltage applied to the DC motor between 0 V and 5 V the maximum values for DC motor input see the DC motor datasheet and read the voltage generated by the tachometer this depends on the tachometer type see the tachometer datasheet 4 Variable Power Supplies NIELVISmx o E bh Digital Multimeter NI ELVISrnx Supply Supply E Manual Manual Voltage Voltage i 1 r a r Ili a gii sh te amp M Measurement Settings Null Offset Instrument Control Acquisition Mode Run Continuously A Run Help stop Heip ea e Figure 6 9 The DMM and VPS Panels Close the DMM and VPS application and the NI ELVIS II Instrument Launcher Lab 6 Introduction to Control 151 8 Start the NI LabVIEW 2010 software and build the application
147. t is drawn Half stepping is based on combining the two sequences One or two of the windings is alternatively activated Thus the number of steps the motor will advance for each revolution of the shaft is doubled and the number of degrees per step is reduced to half Johnson Among the characteristic measures of the stepper motors the most important are enumerated here The limit frequency of starting is the maximum frequency of the command impulses needed for the MPP to start without losing steps The step angle is the angle of the movement of the rotor when a command impulse 1s applied The limit characteristic of starting determines the domain couple frequency domain of the limit command of the stepper motor which starts without losing steps The angular speed represents the product between the step angle and the command frequency The limit frequency of functioning is the maximum frequency at which the motor functions for a durable couple The power at the shaft represents the useful power at the shaft of the motor 96 Lab 4 Interfacing Actuators References J F Cuttino D D Newman J K Gershenson amp D E Schinstock 2000 A Structured Method for the Classification and Selection of Actuators for Space Deployment Mechanism Journal of Engineering Design Vol 11 No 1 March J Johnson 1998 Working with Stepper Motors K R Sullivan Understanding Relays Automotive Series H A
148. tart panel as shown in Figure 1 4 The starting interface is divided into two columns Files and Resources The Files column contains three distinct fields New allows the creation of a new application or of a new project Open offers the possibility of opening an already existing application This field automatically lists the last projects or applications used Targets enables the selection of a required device e g PDA for which the new project is created Lab 1 Introduction T Et LabVIEW 2010 fa R27 wa NATIONAL sion 10 0f2 32 bit Finishing initialization INSTRUMENTS E EE Latest from ni com LabVIEW News 5 fs Empty Project LabVIEW in Action 6 H VI from Template O More W Blank VI Example Programs 2 Training Resources 1 Online Support Di ion F iscussion Forums lf C PQ Starter Kit lvproj I Code Sharing i D Agilent U2500 Series Ivproj KnowledgeBase im C Generate Signal Tremolo vi Request Support C Achizitie Microfon vi Help s C mydaq_equalizer vi Getting Started with LabVIEW C AlarmaTemperatura vi a m ab VIEW D Laborator Acustica Piano vi m E 2009 E LabVIEW 2009 NI CODE clock vi List of All New Features im E LabVIEW 2009 NI CODE clock 6 1 vi Q Find Examples Browse Q Find Instrument Drivers Figure 1 4 Start panel of LabVIEW application The Resources co
149. te Voltage Figure 1 35 then press the OK button 43 Icon Editor File Edit Tools Layers Help Templates IconText Glyphs Layers Figure 1 35 The Icon Editor window with Icon Text For building the connector please go through the following steps o Right click on the icon and select Show Connector Figure 1 36 If the pattern of the connector is not convenient it is possible to select another pattern Figure 1 29 Figure 1 37 t Operate Tools Window VI Properties Edit Icon Show Connector Find All Instances Figure 1 36 The Show Connector selection tage Read vi Front Panel bo la Edit View Project Operate Tools Window i AE u 15pt Application Font J 3 Figure 1 37 Connector editing Using the Wire tool connect the right terminal with the Voltage indicator Lab 1 Introduction 31 q Right click on the icon and select Show Icon Run the application and see the indication on the Voltage indicator Run continuously by pressing the button and see what happens on the Voltage indicator Save the application The Temperature vi For this application we consider that the read voltage is proportional to the temperature in Kelvins We use the following conversion equations for Kelvin scale 7 Celsius scale 8 and Fahrenheit scale 9 K U V a 7 t C U V a 273 15 8 t F U V a 1 8 459 67 9 Open a Blank VI from the start pan
150. th a set of four transistors Lab 4 Interfacing Actuators 107 e qt a oo Figure 4 13 The setup of stepper motor control The electronic circuit was also realized in Multisim for an easier implementation see Figure 4 14 For the first work stage the NI LabVIEW software is started and the application 1s built Panel and Diagram as shown in Figure 4 15 Place in the Diagram the NI ELVISmx Variable Power Supplies express VI which is necessary for supplying the stepper motor with a voltage of 12 V Ifa stepper motor of 5 V is used then the Variable Power Supplies is left out and the motor is supplied directly from the source of 5 V Create a For loop from Execution Control 108 Lab 4 Interfacing Actuators Pim i pe Fe B Sew Toe jee fees Ge Yd Leb Deer e E BS hetOad B20 amp p JF Baaaa BOER e2 tc PRE jk DnR h mA En pu a i Co Teg Tobe OT E a i DE ARLE BORA LE BORAT i TETEA j TETE D g 2d i eN YE rarman hapa HE ved E pes et nT TI na rs S ELL I a h E oe EED M jil is T Li T 7 7 FP _ ESN p o mk fara ria be Tai p m MEL iaiia a Gi sim gt te eed i FEC 7 Ira 1 rs rT aL Se lis 1 mim au TT kj k i He wes Se See EESE Ei H HeRR PHM rrr lla e E EHH id LF TA A ma miei m Dimis E basis I nan CE ma Pana cee gt T a Se mra faias I E EERE fe e farer ak m
151. the solar cell are also presented 170 Lab 7 The Photovoltaic Characterization a l R t Iu hfe SED 1 PA KL can ae ta 2 2 1 inle 2 aD V IR wal Re maA T S gU R eS GV R hle 42 2 agt pay T makT R d Figure 7 3 The equivalent circuit and mathematical model of the solar cell a The ideal circuit b The circuit with parasite resistance c The circuit for the two diode model d The circuit for the three diode model Lab 7 The Photovoltaic Characterization 171 To determine the equivalent circuit of the solar cells in a static regime continuous current the analyses will start from simplified hypotheses The solar cell can be considered a current generator lpn with a current that decreases due to the current through the diode Ig The diode is thus in parallel with the current generator I is the current passing through a resistance of charge R see Figure 7 3 a In order to consider the internal losses in the equivalent circuit the parasite resistances must also be included the series resistance R and the shunt resistance Rsn see Figure 7 3 b The current voltage dependence for a solar cell can be expressed by the double exponential model This model is based on an equivalent circuit with two diodes see Figure 7 3 c In the equation that mathematically renders the model the first term represents the diffusion process of the minority carriers from the depletion layer Th
152. the solar cell By realizing this movement the illumination on the cell can be varied without modifying the spectrum of the light radiation The variation of illumination can be performed 1f there is a source with a variable voltage available By varying the voltage between 10 and 12 V a variation of the cell illumination can be achieved without significantly modifying the spectrum of light radiation c As the acquisition board permits only the measuring of the voltage a resistance 1s used to measure the current R 0 1 Q 1 W The measured voltage is divided in the program to the value of the resistance previously precisely measured A low value resistance is used because the characteristic starting from the point V I R is closer or further from the current axis function of the value of this resistance It is preferable that the starting point of the voltage be as close to 0 as possible The value of the resistance can t be greatly reduced because finally the measurements could Lab 7 The Photovoltaic Characterization 177 be performed under the resolution of the board thus the noise will in fact be measured ra b d p BANANA 4 lhe SA BANANA B a Programs BANANA C Figure 7 8 The setup of raising the I V characteristic of the solar cell d To realize the characteristic a MOSFET transistor will be used IRF2907z with a low resistance Ragonof 4 5 mQ Static Drain to Source On Resistance It is us
153. them in a way that users could easily exploit Now we can add to this the advantages offered by the new NI ELVIS II and NI ELVIS II systems Nowadays NI ELVIS II and the latest release of LabVIEW 2010 offer a recognized universal platform for education The aim of any measuring system is to obtain information about a physical process and to find appropriate ways to present that information to an observer or to other technical systems With electronic measuring systems the various instrument functions are realized by means of electronic components or in some cases by virtual instruments VIs developed in LabVIEW A measuring system may be viewed as a transport channel for the exchange of information between measurement objects in our case sensors or different devices that interact with the NI ELVIS system and target objects see Figure 2 1 Three main functions may be distinguished in this structure data acquisition data processing and data distribution which are described as follows Data acquisition involves acquiring information about the measurement object or objects and converting it into electrical measurement data More than one phenomenon may be measured or different measurements may be made at different points simultaneously requiring multiple inputs Data processing involves processing selecting or otherwise manipulating measurement data according to a prescribed program Often a processor or a computer is used to
154. tic field by applying viscosity Piro piezoelectric actuators Actuators chemically controlled Other types of actuators based on other physical phenomena 90 Lab 4 Interfacing Actuators The actuator has a transducer as a fundamental component this being defined as a device that transforms the non electric energy into electric energy and the other way round see Figure 4 2 Electrical ACTUATOR Port Mechanical 5 Port i Transducer Transducer cs i ie Figure 4 2 Defining the actuator Goal The purpose of this set of exercises is to study the behavior of two actuators using the NI ELVIS II platform The first device that we are going to study is an electromagnetic relay which transforms electromagnetic energy into mechanical energy The targets of the lab exercises are determining the contact resistance of the relay investigating the variation of the coil voltage at the opening and closing of the relay contact and investigating the differences of the auto induced voltage of the relay coil when the relay closes The second device that will be studied is the stepper motor In the lab the emphasis will be on the control of the motor Required Components Component requirements and software application for relays testing are as follows LabVIEW 2010 NI ELVIS II platform and NI ELVIS drivers One electromagnetic relay Chansin of 12 V initial contact resistance 100 mQ LA 24 VDC contact material silver alloy
155. tion i er gt go MW Fo firm a m oO ee i T M L3ILEC TEEN i Synchronizat Graphics amp S Report Gener E User Libraries gt Select a VI FPGA Interface gt RF Communications gt A Figure 1 43 Selection of the String Constant m Make the connections as in Figure 1 44 Temperature Notice that where the wires pass the case structure border between the Temperature icon and the Multiply function and between the Scale icon and the String Constant two tunnels appear These tunnels have white insides This means that it s necessary to connect the wires from all case structure windows n Build the following diagrams and make all the necessary connections as in Figure 1 45 Voltage Temperature Figure 1 45 The Celsius and Fahrenheit case structure windows Lab 1 Introduction 35 Notice that when all connections have been made the tunnels are filled with color o Activate the Panel window Run the VI with different values for Voltage control and select the desired scale from the Scale select control Create the icon and the connector for this VI q Double click or right click and select Edit icon on the icon from the upper left corner of the Panel window and the Icon Editor window Figure 1 46 will appear 3 Icon Editor File Edit Tools Layers Help Templates Icon Text Glyphs Layers V4 A Catego A Filter templates by keyword All Templates 7 da Library Frameworks o
156. tor a HIE HH H oo ao Find All Instances z gm z Figure 1 29 The configuration of the connector If the application needs to run multiple times click on the Run Continuously button The application will run continuously in this case until you click the Abort Execution button Figure 1 30 Run Run Continuously iil Abort Execution Pause Figure 1 30 Execution buttons in LabVIEW applications 26 Lab 1 Introduction Debugging Applications LabVIEW offers several debugging tools The simplest verification of a VI is done by running the VI e clicking on the Run button If the arrow representing the Run button is interrupted and is gray Figure 1 32 the application has errors In order to visualize these errors you need to click on the Run button again An error window will open and describe the errors in this application Figure 1 31 43 Error list BAX Items with errors X Untitled 1 1 errors and warnings Show Warnings d Block Diagram Errors i Case Structure Case Structure unwired selector v Details The Case structure must have a Boolean numeric or enumerated input wired to its selector A terminal the v Figure 1 31 The error window with the error list Another method for application debugging in LabVIEW is to execute the application in animation mode by activating the Highlight Execution option Figure 1 32 Thi
157. ts of the appearance of the maximum forced oscillation amplitude Lab 5 The Study of Vibration 131 The forced oscillation amplitude is a derived function of the pulsation e in order to determine the maximum point and then the result obtained will be equal to zero 3 A ale O y 260 Y 2 20 86o 63 e 4w lo 26 0 64 The resonance frequency is given by the solution of Equation 64 and is Oe 0 28 65 The resonance amplitude of the system under study is obtained by replacing the resonance frequency obtained in Equation 62 which gives the oscillation amplitude _ q Ars 26 a 67 66 Figure 5 8 shows the resonance curves for different values of the damping coefficient Ae ge cece eee ee ee ee e e i Figure 5 8 Representation of the amplitude function of the damping coefficient 132 Lab 5 The Study of Vibration The following steps must be taken to study the forced vibrations 1 Connect the electromagnet to the Function Generator BNC output see Figure 5 5 In function of the used electromagnet a power amplifier is chosen If a power amplifier is chosen it should be interposed between the electromagnet and the Function Generator 2 Modify the application in the preceding exercise as shown in Figure 5 9 and in Figure 5 10 3 Place the Diagram into a Case Structure the NI ELVISmx Function Generator express VI from Function Measurement I OyNI ELVISm
158. ture allows execution of a code variant window selected from several variants depending on the value received by the selector Figure 1 24 Case structure The Sequence Structure The Sequence structure allows sequential execution of code Execution in sequences may be used to implement certain program logic synchronization among several parts of the program debugging and the like There are two types of Sequence structures in LabVIEW 1 Flat sequence the frames are displayed one after another for a better visualization of the code and data flow Figure 1 25 2 Stacked sequence the frames are overlapped on top of each other Selection of any of the frames is made by using the selector placed in the upper central part of the sequence This structure is more compact but less visually clear than the flat sequence Figure 1 26 The addition of a sequence frame is made by pressing the right mouse button against the sequence border and selecting Add Frame After or Add Frame Before 24 Lab 1 Introduction Flat Sequence Structure Figure 1 25 Flat Sequence structure Stacked Sequence Structure Figure 1 26 Stacked Sequence structure The Formula Node Structure The Formula Node structure is used for implementing mathematical formulas and expressions in text mode Figure 1 27 The structure supports MATLAB script and code written in C input variable Lop etal output wariable optional Figure 1 27 F
159. ur computer screen click on the NI ELVISmx Instrument Launcher Icon or shortcut A strip of NI ELVIS II instruments appears on the screen Figure 1 56 You are now ready to take measurements On the prototyping board build a voltage divider Figure 1 58a based on the circuit shown in Figure 1 58b Connect the input voltage Vcc to the 5 V pin socket Connect the common to the GROUND pin socket Connect the external leads to the DMM voltage inputs VQ gt and COM on the side of the NI ELVIS workstation and the other ends across the R2 resistor Check the circuit and power up the NI ELVIS II prototyping board switch on the front of workstation near the prototyping board Verify that everything has been connected the three power indicator LEDs 15 V 15 V and 5 V should now be lit and green in color Start the DMM SFP and press the Run button Notice the measured voltage Stop the measurements by pressing the Stop button Power down the prototyping board Change the R2 resistor and repeat the measurement Lab 1 Introduction 45 XLV1 o DMM COM Figure 1 58 The voltage divider a The voltage divider on the NI ELVIS b The NI Multisim voltage divider circuit design Build a thermometer using the DMM SFP To measure the temperature a LM335 temperature sensor can be used For this sensor the output voltage is proportional with the Kelvin temperature scale The proportionality constant is 100
160. value of the resistance 180 Lab 7 The Photovoltaic Characterization 9 The I V characteristic of the solar cell 1s obtained by unifying the two signals To visualize the characteristic an indicator of the type XY graph is used 10 Power on the NI ELVIS II system and the prototyping board 11 Run the application and visualize the values As in the previous version the data obtained were not saved explicitly but a new version of the software was created to which an express icon was added for the writing of the data Write To Measurement File Figure 7 11 3 LV characteristic with VPSupplay and Save Data vi Block Diagram a s File Edit View Project Operate Tools Window Help 2 1 DIW O a 25 bal P 2 15pt Application Font Bodi AE Solar Cell Voltage i sA Solar Cell I V characteristic E Solar Cell Current TH EAN AT E gt EAN a Vo aw ll mt ib fo b A i NIELVISmx panic i A Write To i Oscilloscope i ri Figure 7 11 The software Diagram for raising the l V characteristic of the solar cell and for data saving Lab 7 The Photovoltaic Characterization 181 Exercise 7 2 Determining the series resistance for a solar cell The series resistance is one of the most important parameters of solar cells Due to the importance of this parameter researchers have realized more than 25 methods for determining it There
161. w these steps 16 Lab 1 Introduction Open the Controls Palette from the pull down menu by selecting View Controls Palette or press the right mouse button in the Panel window Select a Numeric Control from Express Numeric Controls place it on the Panel and call it b write the b character in the control label the black area above the control that contains the Numeric word Repeat the preceding step and call the new control a Select a Numeric Indicator from Express Numeric Indicators place it on the Panel on the right side of the controls and call it x Notice that all three objects from the Panel have a corresponding object in the Diagram Next build the application Diagram as shown in Figure 1 15 43 Untitled 1 Block Diagram File Edit View Project Operate Tools Window ales m E e bal Figure 1 15 The Diagram for solving a first degree equation Activate the Diagram window by pressing the left mouse button inside of the Diagram window or select the option Show Block Diagram from the pull down menu Window Open the Functions Palette from the pull down menu View or press the right mouse button in the Diagram window Select the Negate function from Express Arithmetic amp Comparison Express Numeric Figure 1 16 and place it in the Diagram window as shown in Figure 1 15 Select the Divide function from Express Arithmetic amp Comparison Express Numeric and place it in t
162. wing Stable support for the fixing of the oscillatory system b An elastic steel lamella that will form the oscillatory system c An accelerometer from Analog Devices ADXL325BCPZ with three axes and a maximum range of 5 g d An electromagnet used for inducing the oscillations in the elastic lamella sd NI ELVIS II SERIES PROTOTYPING BOARD AHEHE OHE HAHHAA ot as HES W fer she oo se ee 4 wt gt g H F T eee00 m i ron ABCDE n x Ae D Ae va or 20 Vrms Mal Figure 5 5 The setup for the study of damped oscillations Because the accelerometer used has an operating voltage range from 1 8 V to 3 6 V the supply voltage pin is connected to the variable power supply The sensor is positioned so that the y axis is on the vibrating direction of the lamella The Y Channel Output of the sensor is connected to the first analog input channel ACHO borne ACHO connected to GND To verify the system s functionality the following steps must be taken 1 Build the testing circuit shown in Figure 5 5 2 Start the NI LabVIEW 2010 software and build the application shown in Figure 5 6 and Figure 5 7 126 Lab 5 The Study of Vibration Damp Vibrations v1 vi fos x File Edit View Project Operate Tools Window Help gt Device Name E Boe Study of damp vibrations Vibration Graph p 075 Amplitude t O On 1 1 1 1 1 j 1 1 j 1 1 I 1 1 S 05 O75 1 L5 25 15 2 25 25 25 3 325 35 325 4 4
163. x Create controls for Frequency Hz and Amplitude Vpp inputs and a constant for Signal Route input by right clicking on these inputs and choose the Create Control and Create Constant options respectively Choose the FGEN BNC value for the Signal Route constant 4 Create a Boolean control for the case structure and call it Update In Panel set the values for Horizontal and Trigger controls as shown in Figure 5 9 5 Power on the NI ELVIS II system and the prototyping board 6 Run the application Modify the values of Frequency and Amplitude controls and press the Update FG button Visualize the values 7 It can be observed that the vibration frequency of the lamella is double in comparison with the one generated by the functions generator This happens because the lamella is attracted by the electromagnet on each signal change 8 Observe that by changing the frequency with small values for a short period of time the phenomenon of hammering appears It is caused by the composition of two harmonic vibrations of close frequencies When the frequency generated by the generator is modified the initial vibrations of the lamella are composed with the newly induced vibration by the electromagnet see Figure 5 11 Lab 5 The Study of Vibration File Edit View Project Operate Tools Window Help 1 Study of vibrations Oscilloscope Configuration Detected amplitude 0 188142 Function Generator Configuration _Trigger
164. y are no longer used For more information about PID tuning the references below can be studied References W Bolton 2004 Instrumentation and Control Systems Elsevier LabVIEW PID and Fuzzy Logic Toolkit User Manual http www n1 com pdf manuals 372192d pdf PID Controller http en wikipedia org wiki PID controller PID Theory Explained http zone n1 com devzone cda tut p 1d 3782 A Wolfgang 2005 Practical Process Control for Engineers and Technicians Elsevier Linacre House Jordan Hill Oxford UK Lab 6 Introduction to Control 149 Exercise 6 1 The PID algorithm in speed control Controlling the speed of a DC motor can provide an example of the PID control application The aim of this experiment is to understand how the PID algorithm can be used for speed control The experimental setup consists of a DC motor coupled with a tachometer as a feedback sensor for the motor s speed This setup should be performed on the prototyping board of the NI ELVIS II as shown in Figure 6 8 The DC motor is connected to the variable power supply and the tachometer output is measured using the DMM sone evn war com y gt ome gt Figure 6 8 The setup for DC motor speed control The voltage output specified by the manufacturer of the tachometer is 6 5 V 1000 RTM The input voltage of the DC motor is 5 V At the maximum input voltage the speed of the motor is 3000 RPM This means tha
165. ysical phenomena such as piezoelectrics magnetostriction the shape memory or the bodies dilatation with the raising of the temperature the change of phase the electroreologic effect electro hydrodynamics and the diamagnetism The mechanism of the actuator transforms amplifies and transmits the movement in accordance with the specific parameters of the technological process The function of an actuator can have the following schematic representation see Figure 4 1 Input l Actuator enercy T 5 mechani sm Figure 4 1 The schemata of the actuator s function The main performance characteristics of the actuators according to Zupan et al Cuttino et al are as follows The specific course that is obtained by making a ratio between the maximum course and the length of the actuator measured in the direction of the course The efficiency of the actuator represented by the ratio between the mechanical work produced during a complete cycle and the energy consumed per cycle The specific force that is the result of the ratio between the maximum force generated and the transversal section of the actuator The density that is obtained by neglecting the source mass and the peripheral devices and by making a ratio between the actuator s weight and its volume in the initial shape Lab 4 Interfacing Actuators 89 The coefficient of the work course that is obtained by the ratio between the specific course and the specific forc

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