Laboratory 4 Open Loop Analog Control of a DC Motor
Contents
1. differences between the calibration curves for the two different settings make sense from a physical point of view Explain Your Lab Report should clearly state your name Lab Report number Lab date and your laboratory partner s name if any Your lab report should be thorough but concise You will be graded on quality not quantity Lab Report 4 is due at the beginning of Laboratory 5 Additional Reading Feel free to read the following material to learn more about LabVIEW s analog output features LabVIEW Data Acquisition Basics Manual Chapter 10 Things You Should Know About Analog Output and Page 11 1 Available online at www ni com pdf manuals 320997e pdf 132. 8 10 15 2008 Time sec Figure 1 Front Panel for yourname MotorDrive Tacho vi DAQ_MotorDrive_Tacho FO8 vi Block Diagram fof x File Edit View Project Operate Tools Window Help gt J l om e jed bol off 13pt Application Font MESES so 5 a Analog Input Voltages us Samples Y DaQmx Create Virtual Channel vi DAQmx Timing vi DAQmx Start Task vill DAQmx Read vi DAQ mx DAGmx D L Pal Analog 1D wfm NChan 15amp DAG n Pl sai AO Voltage Y Sample Clock v DAQmx Start Task vi Analog DEL DAQmx Create Virtual Channel vi DAQmx Timing vi 1Chan 15amp Cpa Min TER Polymorphic VI Selector Figure 2 Block Diagram for yourname MotorDrive Tacho vi Experiment 1 Check the Analog Output Voltage Signal Generated by your Virtual Instrument In this experiment you will use a labVIEW VI that will enable you to output an analog voltage signal from your DAQ data acquisition board Analog Output Channel 0 DACOOUT on the DAQ board has already been configured to output voltage signals in the range 5 V to 5 V You will verify the output voltage signal on the oscilloscope as shown in Figure 2 Oscilloscope D A Converter A D Converter DAQ board Figure 2 Analog voltage output from DAQ board to oscilloscope 1 Open yourname MotorDrive Tacho vi 2 To view the analog voltage signal from the DAQ board connect your oscilloscope to the CB 68LP connector block a
3. HD Ul S gt pf cc Q Figure 5 DC Motor Control Module connections for open loop analog control Experiment 3 Obtain Analog Velocity Feedback from the DC Motor Module In this experiment you will use a LabVIEW VI to obtain analog velocity feedback from the tacho generator output of your DC motor control module This system is shown in Figure 6 Oscilloscope D A Converter Drive Circuits x A D Converter Tacho generator DAQ board DC Motor Module Figure 6 Open loop analog control of DC Motor including velocity feedback View Analog Velocity Feedback Signal 1 To view the analog velocity feedback signal use a banana connector to connect the Tacho Generator Output from your motor control module to the CB 68LP connector block according to Table 3 Do not remove the connections you made between the CB 68LP connector block and the motor control module during Experiment 2 Also retain the osciRfsMRieb Medes for viewing purposes Table 3 Pin assignment for measuring a voltage signal using Analog Input Channel 0 TACHO GENERATOR OUTPUT Panel on Motor Control Module Vour socket Analog feedback Pin 68 AI 0 OV socket Analog ground Pin 67 AI GND Run Your VI Open yourname MotorDrive Tacho vi 2 Click the Run button Verify that the voltage viewed on your oscilloscope and Tacho Generator Chart corresponds to the voltage specified by your Motor Drive Input Control A
4. ME 104 Sensors and Actuators Laboratory 4 Open Loop Analog Control of a DC Motor Department of Mechanical Engineering University of California Santa Barbara Fall 2008 Revision Introduction In this laboratory you will write a LabVIEW program that will enable you to drive a DC Motor using an analog voltage signal You will also learn how to measure and view both angular velocity and angular position feedback signals from the motor The DC Motor is part of the MS15 DC Motor Control Module Figure 1 The angular velocity of the motor can be controlled using either an analog voltage signal or a pulse width modulated P W M digital signal In this laboratory we will use only analog signals 360 Precision Eddy Current Drive Motor Potentiometer Brake Slotted Disc Protractor EN Pulse Width Modulation Digital Tachometer Tachogenerator Figure 1 MS15 DC Motor Control Module Background Reading Please read the following material prior to this lab 1 DC Motor Control Module User Manual Pages 3 7 and 14 16 LJ Technical Systems Inc Pre Lab Please build the following VIs prior to this lab 1 yourname MotorDrive Tacho vi Build a VI to generate a DC voltage to drive a motor and read the tachogenerator voltage Open the VI DAQ MotorDrive Tacho FO08 vi located in the melab share drive Save this VI as yourname MotorDrive Tacho vi to the desktop or your network drive Go to the front panel o Select P
5. ccording to Table 1 Table 1 Pin assignments for viewing voltage from Analog Output Channel 0 on oscilloscope Oscilloscope probe Analog voltage Red probe Pin 22 AO 0 Analog ground Black probe Pin 55 AO GND You are now ready to run your VI Verify that the voltage viewed on your oscilloscope corresponds to the voltage specified by your Motor Drive Input Control 3 FOR LAB REPORT Save screenshot of front panel and block diagram 4 To stop running the VI set your Motor Drive Input Control to the OV position and then click the STOP button Experiment 2 Drive the DC Motor Using an Analog Signal In this experiment you will drive the DC motor using the analog voltage output from your DAQ board The open loop analog motor control system is shown in Figure 3 DC Motor Module D A Converter A D Converter Tacho generator DAQ board Figure 3 Open loop analog control of DC Motor The MS15 DC Motor Control Module requires an external power supply that consists of 5V 12V and 12V signals with specific currents Make sure the Tektronix PS280 DC Power Supply is off Configure the DC Power Supply to provide 5V 12V 12V and OV ground Wire the DC Power supply to the Motor Control Module Be sure to connect all OV plugs to ground with a wire ASK YOUR TA TO CHECK THE POWER SUPPLY CONNECTION BEFORE CONTINUING AUN The PCI 6024E DAQ board has two 12 bit analog out
6. control module You will plot this data as part of your lab report If the indicator values are changing not steady observe the changing values for a few seconds and record the lowest value and the highest value 4 Increase the voltage value on your Motor Drive Input Control by 0 20 V and repeat step 3 above Do so up to and including the maximum Motor Drive Input Control t At high velocities the signal displayed on your Potentiometer Chart will be distorted due to aliasing and graphical interpolation effects For better viewing of the potentiometer output signal you may consider simultaneously viewing it using the second unutilized channel of your oscilloscope 11 value of 5 00 V For your convenience you may specify the increment value of your Motor Drive Input Control byright clicking on it and selecting Data Range 5 To stop running the VI set the Motor Drive Input Control to 0 and click the STOP button 6 Repeat steps 1 through 5 but this time use 1 00 V as your starting voltage and decrement the voltage by 0 20 V until you reach 1 00 V 7 Set your digital control to the OV position and stop running the VI Determine Dead Zone If you look at your data you will notice the drive voltage dead zone in which the motor does not turn even though the drive voltage is not zero To determine the exact location of the dead zone you can repeat the procedure outlined in Steps 3 through 7 but wit
7. h a more convenient starting point and a smaller increment or decrement such as 0 01V 8 Turn off your Tektronix PS280 DC Power Supply Experiment 6 Calibrate Velocity of DC Motor Module under External Load Conditions In Experiment 5 you calibrated your DC Motor while the Eddy Current Brake was disengaged in the 0 setting In this exercise you will calibrate your motor with the Eddy Current Brake engaged in the 1 setting 2 3 Retain all the CB 68LP connections and banana plug connections you had at the end of Experiment 4 Open yourname_MotorDrive_Tacho vi Set the Eddy Current Brake to the 1 position and repeat the calibration you performed in Experiment 5 Steps 2 through 8 Saving Files Before you leave remember to save all of your files to your ECI account for later use and backup purposes For this laboratory you should save the following files from the Desktop yourname_MotorDrive_Tacho vi Laboratory Report 1 2 For the VI s you wrote in this laboratory listed in the preceding section provide a printout that shows the front panel and block diagram with working data Provide four tables that contain the data you collected in Experiment 5 and 6 The first and second tables should be for the upward calibration from 5V to 5V for the motor w out brake and w brake and the third and fourth tables should be for the downward calibration from 1V to 1V for the motor w out brake a
8. lso observe the digital OUTPUT SHAFT R P M indicator on the TACHOMETER panel on your motor control module Figure 7 Figure 7 Tachometer panel on DC Motor Control Module 3 FOR LAB REPORT Save screenshot of front panel and block diagram showing data in the chart 4 To stop running the VI set your Motor Drive Input Control to the OV position and then click the STOP button Experiment 4 Obtain Analog Position and Velocity Feedback from the DC Motor Module In this experiment you will use a LabVIEW VI to obtain analog position feedback from the potentiometer output of your DC motor control module The position feedback will be in addition to the velocity feedback you already have This system is shown in Figure 8 Oscilloscope D A Converter Drive ii Circuits he Motor ometer Outo ote A D Converter E i Output Shaft Position Tacho DAQ board DC Motor Module Figure 8 Open loop analog control of DC Motor including position and velocity feedback 10 View Analog Position Feedback Signal 1 To view the analog position feedback signal use banana connectors to connect the Potentiometer Output from your motor control module to the CB 68LP connector block according to Table 4 Do not remove the connections you made between the CB 68LP connector block and the motor control module during Experiment 3 Also retain the oscilloscope connections for viewing purposes Table 4 Pin a
9. nd motor w brake Each table should have separate columns for the Motor Drive Input data the Tacho Generator Output data and the Tachometer Output Shaft RPM data Using the data you tabulated in question 2 above plot Tacho Generator Output voltage versus Motor Drive Input voltage for the No Brake case and Brake case Plot separately the upward calibration curve and the downward calibration curve and clearly indicate which is which Label the dead zone s in your plots Define Vin as the minimum positive smallest magnitude drive voltage that 12 causes the shaft to turn and define Vin as the maximum negative smallest magnitude drive voltage that causes the shaft to turn Clearly label all values of Vin and Vin on your calibration graph Provide a piecewise linear description of the calibration curve you obtained in Question 3 above Make sure your description covers the entire drive voltage range 5V to 5V In particular what are the equations for the linear region s of your calibration curve What would the equations be if you plotted Motor Output Shaft Angular Velocity versus Motor Drive Input voltage Explain and clearly specify units Was the dead zone for your upward calibration equal to the dead zone for your downward calibration Justify your observation from a physical point of view Hint Why does a dead zone occur Compare and comment on the calibration curves for the two different Eddy Current Brake settings 0 and 1 Do the
10. ointer Slide from the Numeric subpalette and place it on the front panel and change the label to Motor Drive Input Control On the block diagram o Wire the Pointer Slide to the DAQmx Read vi o Wire the Pointer Slide to the Merge Signal icon that is connected to the Voltage Signal Chart This displays the Motor Drive Voltage on the Voltage Signal Chart To make the digital display corresponding to the Pointer Slide visible right clicking on the Pointer Slide gt gt Click on Visible Items gt gt Click on Digital Display You can now set the the Motor Drive Voltage using the Pointer slide or entering a number in the Digital Display Set the Pointer Slide properties by right clicking on the Pointer Slide and selecting Properties from the Pop up menu o Data Range tab Range 5 0 5 0 Increment 0 01 Save this completed VI as yourname MotorDrive Tacho vi It should look similar to Figure 1 and Figure 2 DAQ MotorDrive Tacho FOB vi Front Panel of x File Edit View Project Operate Tools Window Help EI DIS 8 u 13pt Application Font x Soll tox ee 5 2 6 Sampling rate Hz ng rate He Dev1 aio ZY Voltage Signal Chart ail i Analog Input Voltages Bom mi Analog Output Motor Drive Voltage kg Dev1 a00 p SR 2 14 Motor Drive Voltage ae fel 2 3 sd 5 KJEND i 1 11 28 12 412 AM 11 28 15 000 AM 11 28 17 412 AM 10 15 2008 10 15 200
11. put channels each with a maximum output rate of 10 kS s t This is to prevent the motor from turning due to random data after you have turned off your VI 6 Find the MOTOR DRIVE switch on your motor control module To specify that you are using analog drive input select the Vin position 7 Find the TACHO GENERATOR switch on your motor control module To enable voltage output reading at the Tacho Generator Output select the Vour setting 8 Find the MOTOR DRIVE INPUT panel on your motor control module To enable the selected input Vin to drive the motor use a banana connector to connect the E Enable Input socket to the OV socket as shown in Figure 5 9 Turn on your Tektronix PS280 DC Power Supply This will provide power to the motor control module 10 Make sure the Eddy Current Brake is disengaged That is make sure that the Eddy Current Brake Position Indicator shown in Figure 4 is in the 0 position Eddy Current Brake Position 360 Precision h Eddy Current Potentiometer Brake Drive Motor Slotted Disc Protractor Disc Gray Code Disc Output Shaft a LSD R J Pulse Width ff Modulation Tachometer Tachogenerator Figure 4 Eddy Current Brake Position Indicator on DC Motor Control Module 7 To drive the motor module with the analog voltage signal generated by your VI connect the voltage input socket Vin on the Motor Drive Input Panel shown in Figure 5 of the motor cont
12. rol module to the CB 68LP connector block according to Table 2 Do not remove the connections to the oscilloscope Table 2 Pin assignment for using voltage from Analog Output Channel 0 to drive DC Motor MOTOR DRIVE INPUT Panel on DC Motor Control Module Vin socket Analog voltage Pin 22 AO 0 OV socket Analog ground Pin 55 AO GND You are now ready to drive your DC Motor 8 Open yourname_MotorDrive_Tacho vi 9 Click the Run button to drive the DC Motor using the voltage output from your DAQ board Verify that a positive voltage from the Motor Drive Input Control results in counterclockwise rotation while negative voltage from the same Motor Drive Input Control results in clockwise rotation Observe that the DC Motor does not move for drive voltages very close to 0 V The small voltage neighborhood within which the motor does not move is known as a dead zone and is a result of friction and a few other effects 10 You DON T need to save the vi for this part of the lab just verify that it works 11 To stop running the VI set the Motor Drive Input Control to the OV position in your VI and then click the STOP button Motor Control Board Layout 2 MOTOR ComTROL MODULE i 5 ANALOGUE CONTROL MOTOR DRIVE INPUT Banana Motor Drive Input Connector Panel TACHO GENERATOR OUTPUT F ttt Qv ov ov il POTENTIOMETER OUTPUT I i i ICT Over OS OG AG PE
13. ssignment for measuring a voltage signal using Analog Input Channel 1 POTENTIOMETER OUTPUT Panel on Motor Control Module Vour socket Analog feedback Pin 33 AI 1 OV socket Analog ground Pin 67 AI GND Run Your VI Open yourname MotorDrive Tacho vi 2 Click the Run button Verify that the voltage viewed on your Potentiometer Chart agrees with the voltage specified by your Tacho Generator Output Chart That is the frequency of the signal on your Potentiometer Chart should increase with rotation speed 3 FOR LAB REPORT Save screenshot of front panel and block diagram showing data in the chart 4 To stop running the VI set your Motor Drive Input Control to the OV position and then click the STOP button Experiment 5 Calibrate Velocity of DC Motor Module In this experiment you will document the motor drive signal and velocity feedback signal from your motor control module By plotting this data you can calibrate the angular velocity versus drive voltage behavior of your open loop system 1 Retain all the CB 68LP connections and banana plug connections you had at the end of Experiment 4 Run Your VI 2 Click the Run button for yourname_MotorDrive_Tacho vi Obtain Data 3 Enter 5 00 inthe Motor Drive Input Control FOR LAB REPORT record the voltage values shown on the Motor Drive Input Control andthe Tacho Generator Indicator Also record the value shown on the OUTPUT SHAFT R P M indicator on your motor
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