Masterarbeit_Verteidigung

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Closed-loop Motor Position Control at arcsecond precision for the ERIS Project at VLT (Very Large Telescope)

AMR AWAD STUDENT NUMBER: 840804

05/01/2023

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2Agenda

1. About Max Planck Institute for Extraterrestrial Physics and the Project (ERIS)2. Introduction to the Master Thesis Contribution3. The Project Setup4. Direct Motor Control5. Motor Control with the Grating wheel6. Conclusion

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3Agenda

1. About Max Planck Institute for Extraterrestrial Physics and the Project (ERIS)

2. Introduction to the Master Thesis Contribution3. The Project Setup4. Direct Motor Control5. Motor Control with the Grating wheel6. Conclusion

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4Max Planck Institute for Extraterrestrial Physics (MPE)

MPE research fields and approach• modern astrophysics and space plasma research

MPE instruments• Above the dense Earth (Satellites)• Ground-based observatories (Telescopes)

Electronic group• Structure (developing, engineering and workshop)• Developing concept Engineering Constructing

Testing Commissiong

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5ERIS Project

ERIS: Enhanced Resolution Infrared Spectrometer SPIFFI instrument at VLT

• SPIFFI: SPectrometer for Infrared Faint Field Imaging• VLT: Very Large Telescope

About the telescope physical measurement• Near InfraRed (NIR) Imaging

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6Agenda

1. About Max Planck Institute for Extraterrestrial Physics and the Project (ERIS)2. Introduction to the Master Thesis Contribution3. The Project Setup4. Direct Motor Control5. Motor Control with the Grating wheel6. Conclusion

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7Grating Wheel

holds four gratings for the different wavelength bands (J, H, K, High Resolution J/H/K)

Accuracy of 2 arcsec Setup notes:

• First functional tests of the Grating-Wheel mechanism without Gratings have been done.

• Turns ration is not precisely defined• Test setup does not have Indyctosyn

Motor+Resolver

Inductosyn Gear

Gratings

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8Agenda



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9Project Block diagram

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10Agenda



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11Problem definition

Motor Control Problem

Rated TorqueMicro-

stepping (512 micro-steps

test)

Open loop Closed loop

Position control

Resolver feedback

Resolver and Autocollimator

feedback

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12Test setups (1)

1. Motor axis slot to fix the lever to the motor2. Lever3. Weight

Translation motion Reflected light position changes in Y AND Z

with the mirror motion Moving light focus in an arc Theoretically covers 610 Micro-steps Practically Moving dot (Reflected light)!

4. Mirror carrying structure5. Mirror’s reflexive surface

Y

Z

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13Test setups (2)

Rotation motion Reflected light position changes in Z with the

mirror motion Moving light focus in a line Theoretically covers 9 Micro-steps Practically less degrees of freedom but

easier for control Practically same pattern like the grating

wheel 1. Motor axis slot to fix the lever to the motor2. Lever3. Weight

4. Mirror carrying structure5. Mirror’s reflexive surface

Y

Z

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14Load torque characteristics

Aluminium lever: M [mNm] = 67.836 [mm]* 0.5778 [N] +m [kg]*9.81*(95 [mm] –a [mm])

Vanadium lever: M [mNm] = 56.73 [mm]* 1.0546 [N] +m [kg]*9.81*(95 [mm] –a [mm])

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15Results for Motor: 42.200.2,5

Lever Weight a [mm] M [mNm] Max_Y Min_Y Range_Y

Al

without N.A 39.1956 104.5 100 4.5

Al

72.01 46.4352148 121.7 111.2 10.561.03 49.8928278 -147.3 -156.6 9.350.01 53.3630368 -348.9 -370.8 21.939.09 56.8017557 -240.7 -251.8 11.1

28 60.2940078 182.8 168.1 14.7

VA

71.99 59.8271891 97.1 66.2 30.961.01 69.6722305 260.5 246.7 13.850.02 79.5262381 -104.3 -133.2 28.939.01 89.3981785

VA

without N.A 59.8275 83.1 77.2 5.9

Al

72 67.070181 151.7 132.5 19.255.02 72.4172 3.7 -10.8 14.5

41.5 76.6746615 13.6 7.2 6.427 81.240726 34.3 22.6 11.7

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Rated TorqueMicro-


test)


Position control

Resolver feedback


feedback

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17512 Micro-stepping test (Open loop)

ssd Load Torque:40, 50, 60, 65, 70 [mNm]

Reduced Current:500, 1000,1500, 2000, 2500 [mA]

Statistical approach

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18512 Micro-stepping test (Closed loop)

ssd Load Torque:40, 50, 60, 65, 70, 80 [mNm]

Reduced Current:Minimum reduced current (Bisection approach in equation roots finding)500, 1000,1500, 2000, 2500 [mA]

Statistical approach

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19512 Micro-stepping application

LabVIEW TWINCAT 3 (Tc2_MC2)

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20Sample result: Open loop, 40 [mNm], 2500 [mA] (Current/ Torque)

Motor cycles:• 128 up 256 down 128 up

Holding Torque Equation:

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21Sample result: Closed loop, 40 [mNm], 1000 [mA] (Current/ Torque)

Motor cycles:• 128 up 256 down 128 up

Holding Torque Equation:

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22Sample result: Position diagram Open loop vs. Closed loop

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23Sample result: Position Error diagramOpen loop vs. Closed loop

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24RMS Error (Open loop, Motor: 33.200.2,5)

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25RMS Error (Closed loop, Motor: 33.200.2,5)

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26Maximum Load Torque Motor: 33.200.2,5

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Rated TorqueMicro-


test)


Position control

Resolver feedback


feedback

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28Position control loop

Setpoint scale: 10: 350 °

OPC UA (Realtime problem) PLC blocks update Enable/ Disable time

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29Position control loop with two sensors(fine tuning)

Setpoint scale:• 10: 350 °

Sensors reading normalization to avoid abrupt control action at the transition point

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30Position control loop application

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31Sample result: Kp= 0.0001, Enable time = 20 [ms], Disable time= 50 [ms]

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32Agenda


2. Introduction to the Master Thesis Contribution3. The Project Setup4. Auxiliary Tools5. Direct Motor Control6. Motor Control with the Grating wheel7. Conclusion

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Grating wheel control problem

Homing Gear ratioMicro-


test)


Position control

LabVIEW via OPC UA PLC control

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34Motor referencing procedure

1. Initial position2. Reference switch latch detection3. Motor stop4. Travelling backwards5. Signal synchronization (omitted)6. Reference switch release detection7. Stop at Home Position

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35Motor referencing results

Mechanical response of the limit switch

Central limit theory Normal distribution

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test)


Position control


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37Gear ratio estimation

Homing one complete Homing at the new reference Counting the number of revolutions made by the motor

(LabVIEW interface with the absolute 16 bit encoder) Statistical approach of the gear ratio estimation Estimated gear ratio = 2097.142 Calculated Variance= 0.273731 Calculate standard deviation = 0.523193

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test)


Position control


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39512 Micro-stepping test (Open loop)

Load Torque:Grating Wheel

Reduced Current:250, 500, 750, 1000,1500, 2000, 2500 [mA]

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40512 Micro-stepping test (Closed loop)

Load Torque:Grating Wheel

Reduced Current:250, 500, 750, 1000,1500, 2000, 2500 [mA]

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41Sample result: Position diagram at 2500 [mA]Open loop vs. Closed loop

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42Sample result: Position Error diagram at2500 [mA] Open loop vs. Closed loop

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43Sample result: Resolver vs Autocollimator at 2500 [mA] Open loop vs. Closed loop

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44Sample result: Resolver vs Autocollimator Offset- Open loop vs. Closed loop

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test)


Position control


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46Position control loop (LabVIEW via OPC)

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47Position control loop (PLC)

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48Sample result: Full pathError < 0.02 [arcsec] (grating wheel side)

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49Sample result: Half pathError < 0.02 [arcsec] (grating wheel side)

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50Agenda


2. Introduction to the Master Thesis Contribution3. The Project Setup4. Auxiliary Tools5. Direct Motor Control6. Motor Control with the Grating wheel7. Conclusion

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51Conclusion

Control achieved in open and closed loop (2 [arcsec] precision) OPC UA real time limitation Feedback from the grating wheel side is much better Inductosyn Limit switch changing with better preciseness to be used with the

Inductosyn

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52

Thank You!

Masterarbeit_Verteidigung

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