User Manual - Olin-NASA Research Group
Contents
1. 1018 Carbon Steel Finish Coating Unpolished Mill Maximum Attainable Hardness Rockwell B72 Yield Strength 55 000 psi Four 4 6 32 through holes for mounting Four 4 4 40 through holes for actuator mounting Two 2 countersunk holes for transformer mounting Actuator Grips 1018 steel from McMaster Carr P N 8910K598 0000000 0 e See Section 8 for drawing and dimensions Thickness 0 25 Thickness Tolerance 0 003 1018 Carbon Steel Finish Coating Unpolished Mill Maximum Attainable Hardness Rockwell B72 Yield Strength 55 000 psi Two 2 4 40 holes for baseplate mounting One 1 4 40 hole for grip tightening 14 Fasteners Screws Size 4 40 Screws from McMaster Carr P N 90272A115 90272A106 Length 1 0 for mounting grip Length 0 25 for grip attachment Material Steel Zinc Plated Head Style Pan Drive Style Phillips Thread Size 4 40 Decimal Size 0 112 Head Diameter 0 219 Head Height 0 080 Thread Point Style Standard Machine Rockwell Hardness B70 Minimum Tensile Strength 60 000 psi 0000000000 0 0 Size 2 56 Screws from McMaster Carr P N 90022A096 Length 0 375 Material Steel Zinc Plated Head Style Pan Drive Style Allen Thread Size 2 56 Decimal Size 0 068 Head Diameter 0 167 Head Height 0 062 Thread Point Style Standard Machine Rockwell Hardness B70 Minimum Tensile Strength 60 000 psi 0000000000 02. 15 Nuts Size 4 40 for mounting grips from McMaster Carr P N 90760A005 Undersized Machine Screw Hex Nut Height 0 0625 Width 0 1875 Material Steel Zinc Plated Grade 2 Thread Size 4 40 Right Hand Thread Standard Threads Rockwell Hardness Maximum C44 00000000 0 Washers Size 4 40 Belleville Washers from McMaster Carr P N 9712K53 Material Steel Non Serrated Inside Diameter 0 125 Outside Diameter 0 25 OOOO Size 2 56 Belleville Washers from McMaster Carr P N 95221A101 Material Steel Non Serrated Inside Diameter 0 09 Outside Diameter 0 20 OOOO 16 Circuit Op Amp OPA551PA from Digikey P N OPA551PA ND 30 V 200 mA Slew Rate 15 Vms Bandwidth 3 MHz OOOO Transformer Audio Output transformer for high impedance wires from Radio Shack P N 273 1380 Turn ratio 11 1 Input 1 kQ Output 8 2 Tested at 77 K OOOO Mono Audio Cable P N 42 2387 o Connection size 1 8 to 1 8 o Length 6 ft 17 7 Frequency Response Report The performance of the oscillator assembly was tested at various frequencies at room temperature 296 K The accelerations output by the oscillator assembly were measured using an Endevco 2272 Accelerometer which was calibrated to output 3 V per G The accelerations on the test mounting were used to calculate the accelerations that would occur if the assembly was mounted on a 10 kg mass The
3. 4 Attach the amplifier circuit to a computer via a 3 5 mm mono audio cable Plug a 3 5 mm mono audio cable into the small black audio port on the amplifier circuit The other end of this cable should be plugged into the audio port of a computer that supports MATLAB 7 0 5 Open MATLAB 7 0 and run control m Open MATLAB 7 0 and navigate its current directory to the folder containing control m and control fig Type control into the MATLAB interface to launch the program 6 Calibrate the output of the control program Set the sound card volume on the computer at a value that corresponds to the normal listening volume of the computer if head phones were in use Set the output amplitude to 1 by opening the Adjust Output window in the Calibrate pull down menu Close the Adjust Output window Select the top line in the program window Enter 2000 in the Frequency Hz field and 5 in the Duration s field Connect a floating scope across the two output wires of the ampllifier circuit in order to measure the output waveform Click Test Selected Line and observe the output waveform If the wave form is clipping open the Adjust Output window again and reduce the output amplitude The oscillator functions best at the greatest amplitude that does not result in clipping This calibration should be done at the beginning of each use 7 Run program with desired frequencies In the control program window input t
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5. the high impedance wiring within the dewar This is because the voice coil works more efficiently with a high current and a low voltage Circuit Diagram Signal Input oe 1 uF Transformer 11 13 Voice Coil 10 Ohms Connecting the Circuit The amplifier circuit should be connected to a 18 V power supply via banana clips Higher voltages may result in op amp failure even though it is rated to 30 V A 3 5 mm mono audio cable should be plugged into the signal input port The other end of this cable should be plugged into the audio output port of the computer that is supporting the oscillator control software The orange output leads of the amplifier circuit should attach to the blue and green leads of the transformer via a feed through on the dewar Each connection port wire is labeled in the diagram below Ground wm or e e ue e wm ue e mg mm gn 1000000009000 000000N5 300000095 tlll ia y 1009994 Ss To EK Ae ez Output Leads to Voice Coil 10 Ohm Shunt Wem Audio Signal Input Performance In room temperature testing the circuit was found capable of delivering high quality waveforms to the oscillator over the majority of the desired frequencies 60 2000 Hz This waveform had an amplitude of approximately 400 mA Details of experimental data can be found in Section 7 The quality of the voice coil current waveform should improve sionificantly at cryogenic temperatures 4 K be
6. Mechanical Oscillator User Manual Franklin W Olin College of Engineering Olin NASA Research Group Summer 2005 Table of Contents Lick Sas 3 ee EOS 5 gt pling Cireuitana Transtornos pia 7 O re ene erent eens 9 ee 11 KE rada 12 STE QUEEN RESPONSE EDO Ls e 18 SE e Sch GE Ee 29 TO ACRO OWL Ed o EENS E E E E E O 23 1 Quick Start Guide 1 Mount oscillator to target object with 6 32 size screws The oscillator assembly should be mounted to the target object using 6 32 size screws The base plate of the assembly has four through holes one at each corner dimensioned to accommodate these screws The assembly should be attached using all four of these holes to ensure a strong connection 2 Connect blue and green transformer leads to orange leads on amplifier circuit The blue and green leads coming from the transformer which is mounted to the base plate must be attached to the orange leads coming from the bottom of the amplifier circuit Since the amplifier circuit was designed to function at normal room conditions these connections must be made via a feedthrough to the outside of the dewar 3 Attach 18 V power supply to amplifier circuit Connect a 18 V power supply to the amplifier circuit via banana clips The 18 V lead should be plugged into the red port labeled with a The 18 V lead should be plugged into the red port labeled with a A grounded lead should be plugged into the black port
7. am Chan Brandeis University
8. cause the resistance in the wiring of both the transformer and the voice coil becomes negligible This improvement may allow for high quality waveforms at frequencies as low as 20 Hz Replacing Components Note Before making changes to the circuit or adjusting components be sure that it is disconnected from the computer and the power is off Otherwise power may be inadvertently back fed into the computer Over the course of its use some components in the circuit may burn out or otherwise break The OPA551 can be replaced by simply pulling out the damaged one and pushing a new one into its place It is important to orient the replacement op amp such that the semicircular notch on the op amp is close to the positive input terminal All other components must be removed by melting away the solder that holds them in place 4 Software Control Program Overview The control software was designed to be easily customized and to operate within multiple operating systems Developing the application and interface using MATLAB permits the software to be run from any system that supports this program OSX Windows XP etc The output from the software was directed through the audio output port of the computer because the sound card on a computer outputs a relatively accurate reproduction of sound sources in the range of 1 V Since sound cards on different computers may output waves of different amplitudes a configuration option was included that woul
9. d alter the amplitude of the output wave as to provide similar output conditions regardless of which computer is used Launching the Application The application was developed in GUIDE so it consists of two files control Ge and control To launch the application navigate MATLAB s current directory to the folder containing both of these files then either type control into MATLAB or run the z file This causes the following window to be displayed Oscillation Control Program ele File Calibrate Help Y Oscillation Program Frequency Hz Duration Test Selected Line Calibrating the Output Set the sound card volume on the computer at a value that corresponds to the normal listening volume of the computer if head phones were in use The calibration tool scales the output of the program by a factor between O and 1 where 1 is the maximum output possible The value of 1 will roughly correspond to 1 V output but this might vary from computer to computer To calibrate the output amplitude of a specific computer open the Adjust Output window seen below in the Calibrate pull down menu Set this value to 1 and Close the Adjust Output window Select the top line in the program window Enter 2000 in the Frequency Hz field and 5 in the Duration s field Connect a floating scope across the two output wires of the driving circuit in order to measure the output wav
10. eform Click Test Selected Line and observe the output waveform If the wave form is clipping open the Adjust Output window again and reduce the output amplitude The oscillator functions best at the greatest amplitude that does not result in clipping This value will not be saved onto the hard drive so each time the application is launched this value will need to be set To edit the default amplitude of the output wave see Customizing the Application Amplitude Please enter the desired amplitude of the output waveform such that the output i t possible output Running the Application The frequency and the length of the output can be set in the Frequency Hz and the Duration s fields There are two options for outputting sound waves with the program either one specific line or all five lines sequentially Using the Test Selected Line command may be helpful for configuring the oscillator before testing begins Lines may be selected by clicking the round button on the left of the desired line For substantial data collection the Run Program command will be useful When the Run Program button is pressed the application will progress through each line that contains a frequency and duration If these parameters are not present it will move on to the next line The button of the current line will be selected and the parameter fields will be green while that line is being played The image below demons
11. ers should be placed between the heads of the screws and the grips as well as between the nuts and the ops After the actuator is secured the centering springs may be placed along the moving magnet as described previously Next the counter masses should be attached These masses are held on to the magnet via 3 8 long 2 56 size screws Size 2 56 Belleville washers should be placed on either side of the mass before screwing the mass to the magnet Attaching the Assembly to the Target Object The oscillator assembly should be mounted to the target object using 6 32 size screws The base plate of the assembly has four through holes one at each corner dimensioned to accommodate these screws The assembly should be attached using all four of these holes to ensure a strong connection 3 Amplifier Circuit and Transformer Circuit Overview The circuit diagram below is a graphical representation of the amplifier circuit This circuit is a current driven operational amplifier circuit A current driven circuit was desirable because it prevents the voice coil current from varying as the resistance of the feed through wiring varies The op amp used in this circuit was an OPA551 See op amp specs in Section 6 The transformer shown in the circuit diagram is actually separate from the amplifier circuit It is attached to the base plate of the oscillator assembly and is placed inside the dewar This transformer was necessary to connect the voice coil to
12. gs keep the magnet centered within the voice coil without substantially affecting its travel The transformer connects the actuator to the amplifier circuit which is kept outside of the dewar Details about the function of the transformer can be found in Section 3 Specs for all of these components are available in Section 6 Mounting System The mounting system for the oscillator assembly consists of three main parts two actuator grips and a base plate These pieces were cut from 1 4 1018 steel This is the same steel of which the casing of the actuator is made This prevents any damage to the actuator that may have otherwise occurred due to thermal contractions Drawing files for these parts are in Section 8 Assembling the Oscillator System To begin assembling the oscillator system the actuator should be placed through both of the actuator grips The grips should then be generally positioned over the threaded holes in the base plate Two 1 4 long size 4 40 screws may be used to attach the grips to the base plate Each screw should be screwed in to half its length before any of the screws are tightened A size 4 40 Belleville washer should be placed between the head of each screw and the grip to ensure tight connects after thermal contractions The actuator can be secured in the grips by placing a 1 long size 4 40 screw through the holes in the top of the grip and tightening a nut on the other end of the screw Belleville wash
13. he counter masses and springs should be removed To open the voice coil note that there is a snap ring on one side of the oscillator Removal of the snap ring with pliers allows access to the inside of the assembly 11 6 Components Oscillator System Actuator Non Commuted Direct Current Moving Magnet Linear Actuator from H2W Technologies P N NCM02 05 005 4JB Serial G501 0000000000000 0 0 See Section 8 for drawing and dimensions Power Rating 3 5 W Voltage Rating 3 5 V Current Rating 1 A Casing Material 1018 Steel Magnet Travel 0 15 Max Acceleration 20 G Continuous Force 5 lbs Peak Force 1 5 lbs Average Km 0 27 lbs W7 2 Total Mass 0 067 lbs Moving Mass 0 026 lbs Inductance Room Temp 0 2358 mH Inductance 77 K 0 2262 mH Resistance Room Temp 3 38 Q Resistance 77 K 0 649 Q 12 Centering Springs Compression Springs from Century Spring Corporation P N 10572 OOOOOOOO k 1 1 lbs in OD 0 234 ID 0 210 Free Length 0 310 Max Deformation 0 250 Max Load 0 270 lbs Wire Diameter 0 012 Number of Turns 4 5 Counter masses Lead from McMaster Carr P N 9054K23 OOOO Welght 0 054 lbs each OD 0 95 Thickness 0 18 Through Hole 2 56 13 Mounting System Base Plate 1018 steel from McMaster Carr P N 8910K598 0000000 0 0 See Section 8 for drawing and dimensions Thickness 0 25 Thickness Tolerance 0 003
14. he desired frequency and time duration of the signal Up to five signals can be played sequentially Click Run Program to begin driving the oscillator The frequency currently being played should become green 2 Oscillator Assembly Assembly Overview The solid model shown below is graphical representation of the oscillator assembly This assembly is intended to be placed inside the dewar and operate at 4 K This assembly was tested at temperatures as low as 77 K at which it was still fully functional At room temperature the oscillator was found to able to produce vibrations that when attached to a 10 kg mass would have magnitudes on the order of mG s The assembly was found to have resonances at 530 Hz as well as 2500 Hz At these frequencies vibrations of approximately 30 mG s were predicted Details of the experimental data can be found in Section 7 BI Mounting Base Plate Actuator E Actuator Grips Bi Transformer El Counter Masses Oscillator System The actuator used in this system is a moving magnet linear actuator purchased from H2W Technologies This actuator functions on the principle of a voice coil The lead counter masses mounted to each end of the moving magnet are approximately 25 g This mass is great enough to produce accelerations on the order of mG s on a 10 kg mass Compression springs were placed along the magnet between the counter masses and the end of the actuator casing These sprin
15. magnitudes of these accelerations along with the input parameters of the experiment were recorded in the tables at the end of this section A plot of the projected acceleration as a function of frequency is shown below Frequencies below 60 Hz resulted in jagged acceleration waveforms particularly in the trials that included the transformer The waveforms both with and without the transformer improve at colder temperatures due to decreased resistance and inductance in both the actuator coil and the transformer This decrease in resistance is also predicted to result in greater maximum accelerations Therefore more force will be exerted by the assembly at 4 K than at the room temperature 45 00 40 00 35 00 30 00 25 00 20 00 15 00 10 00 Projected milliG s on 10kg Mass 5 00 0 00 N O O O Y O 100 O O O O O Li O DO O O O O O O O O CH o O N FT 1600 1800 2000 2500 3000 3500 4000 4500 5000 Without Transformer With Transformer Frequency At low frequencies the force produced in the trial by the oscillator assembly with the transformer has noticeably lower amplitudes than the trial without the transformer This variation in amplitude is due to some properties of the transformer The discrepancy between the setups disappears when the assembly was subjected to cryogenic temperatures because the resistance of the
16. transformer becomes significantly reduced This in effect reduces the magnetizing inductance of the coils which yields higher quality output at low frequencies Two resonances are apparent at approximately 500 Hz and 2500 Hz It is believed that these are due to properties of the mounting system and testing setup 18 Warm Testing Calibration Without Transformer Power Supply Voltage to G s Shunt Resistor Voltage V Scaling Factor In Gircuit 9 om 33 1 Ohm Frequency Hz Audio Output mV Voice Coil Current mA Accel Voltage V Output G s le eee Notes on 10 kg mass 23 36 lrregular Wave Form 12 41 Irregular Wave Form Irregular Wave Form Warm Testing Calibration With Transformer Power Supply Voltage to G s Shunt Resistor Voltage V Scaling Factor In Gircuit Frequency Hz Audio Output mV Voice Coil Current mA Accel Voltage V Output G s ola Notes on 10 kg mass 5 84 Irregular Wave Form 5 84 Irregular Wave Form Irregular Wave Form somewhat Irregular 1 10 Irregular Wave Form 0 95 Somewhat Irregular Note All Volt Amp and G data values are in the chart are 20 8 Drawing Files Mounting System a 21 Actuator L600 0 afr s00 S0 cOINON MOI Ysa A DAA AA AA AE 19 VEN 55216 VO TUAMA 199301 AY OD Eat Duy saou L MZH SCHER POY YEO 99104 snonunuog ZILU MEM EN ZC 0 JUBE SUOD 89104 PS enoo alyadeg pamer a o
17. trates how an active line will appear Customizing the Application To edit the graphical layout of the application type guide into MATLAB and this will launch the GUI development tool To edit the default amplitude of the output wave change the value on lines 22 and 201 to the desired value This will be the amplitude that the program will run at upon launch 10 5 Troubleshooting Unusual Waveform In some cases the output of the amplification circuit appears as below When this happens the op amp is not functioning properly and must be replaced When replacing the op amp it should be positioned so that the semicircular notch is closest to the positive voltage port Replacing this component should solve the amplification circuit s problems Note Before making changes to the circuit or adjusting components be sure that it is disconnected from the computer and the power is off Otherwise power may be inadvertently back fed into the computer Amolitude wl al 8 0 01 0 008 0 006 0 004 0 002 O 0 002 0 004 0 0068 0 008 0 01 Time te Clipping Waveform If clipping is noticed on the output waveform of the circuit follow the instructions in Section 3 under Cahbrating the Output Choppy Voice Coil Movement If the moving magnet in the voice coil clicks or no longer moves smoothly this may mean that it is dirty or otherwise clogged The voice coil may be opened and cleaned Before opening the voice coil t
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