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TRR Team SAVI Satellite Active Vibration Inverter

Wasseem Bel Joseph Schmitz

Patrick Byrne Justin Tomasetti

Blake Firner Jackson Vlay

Corey Hyatt Benjamin Zatz

Project Purpose

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• Develop a Satellite Active Vibration Inverter (SAVI) mount system that will identify and cancel low frequency vibrations from a cryocooler that cause image smearing on a telescopic camera.

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Cryocoolers create Exported Forces and Torques (EFTs) • Frequencies dynamically range from 40 to 60 Hz • Amplitudes on the order of 20 microns (twice the

thickness of a sheet of paper)

Simulated Telescoping Camera Payload • 3.19 kg simulated mass • 1 𝜇rad Pixel Resolution

Image Smearing • Pixel Movement

• Angular Displacements from EFTs

These EFTs will cause up to 150 pixel smear 1- Cryocooler 2- Simulated camera payload 3- SAVI system

Budget Test Readiness Schedule Overview

SAVI and Test Stand Details

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• Flexures placed on top and bottom of actuating legs to avoid shear stresses in piezoelectric actuators

• Flexures placed on top of solid leg to allow for plate rotation

• Accelerometers placed on top plate next to each leg and on bottom plate next to the two actuating legs


SAVI Actuating Leg

Accelerometer

Solid Leg

Top Plate

Base Plate

Top Plate

Base Plate

Actuating Leg

P176.50 Flexure

Test Stand

Solid Leg

P176.50 Flexure

Simulated Mass

Levels of Success

Level 1: • Pixel smear reduced by 60% to about 60 pixels of smear

Level 2: • Pixel smear reduced by 80% so that about 30 pixels or fewer are smeared

• Signal frequency has dwell time of 2 seconds

Level 3: • The system dimensions will not exceed 20 cm x 20 cm x 10 cm

• The system mass will not exceed 5 kg

• The system will use no more than 10 W of power

4 Budget Test Readiness Schedule Overview

Critical Project Elements

• Acquire Vibrometer • Verify 20 𝜇m displacement • Testing Location • Scheduling • Off Ramp

• Full System Laser tests • Revisit test location choice

• Electronics enclosure box

• Originally not part of design, but was added due to recommendation

• SAVI and Test stand assembly • Small parts need to be assembled

to complete SAVI and test stand • Integration of purchased flexures


Updates

• Flexures have been purchased for the actuator tips to ease connection and mitigation of associated risk.

• Looking to rent a vibrometer from Polytec for actuator and full system validation of 20 micron displacements

• Testing location set to occur in the ITLL and Aerospace Wing • Testing at Ball not feasible due to occupancy of onsite facilities

• Top plates must be redone to accommodate the new flexures

• Enclosure box added to electronics design


Schedule


Noise Test

• Requirements • Testing environment must have no frequency peaks in the 40–60 Hz range

-FR.1 → DRT.2: Ambient noise in operational range shall not have peaks exceeding background noise level.

• Test site shall have no more than 1 mV of background noise. -FR.2, FR.5 → DRT.2: SAVI testing environment shall not have greater than 1 mV of background noise.

• Objective • The testing site must be viable for SAVI to operate with high signal to noise

ratio

8 Overview Budget Test Readiness Schedule Overview

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Noise Test Protocol

1. Accelerometers will be connected through the signal conditioner to the cDAQ input module 2. Accelerometers placed atop background damping system (if needed) 3. Data will be collected for 2 minutes at 16 kHz 4. Frequency analysis of the noise data will be done using FFT to check for peaks in operational range 5. Analysis of peak-to-peak noise amplitude of data

MATLAB Code

DAQ

Charge Amplifier

Accelerometer

Foam Background damping (if needed)


Noise Test Verification and Validation

• Key Measurements: • Maximum and mean ambient noise amplitudes

• Frequency of ambient noise

• Desired Results: • The testing location will be proven to be viable

• Frequency analysis of noise data shows no peaks in operational frequency range

• Maximum of 1 mV peak-to-peak noise in ambient noise data

• Impact of Results: • Full system test can be completed at chosen location


Actuator Test Requirements

• Requirements • Electronics shall operate at specified actuation between 40-60 Hz

• FR.2 → DRE-1: Electronics shall perform between 40-60 Hz

• System shall be capable of producing 20 𝜇m vibrations • FR.2 → DRE-2: System shall measure and produce vibrations up to 20 𝜇m

• Objective • SAVI will be capable of actuating at 20 𝜇m amplitude between 40-60 Hz


Actuator Test Protocol

1. Setup an actuator with an accelerometer attached to actuating tip

2. Align laser vibrometer with actuator accelerometer pair

3. Input 20 𝜇m peak-to-peak signal into actuator at specified frequency

4. Collect vibrometer data and accelerometer data for 20 seconds

5. Analyze accelerometer output and compare with vibrometer data to compare accelerometer displacement prediction with vibrometer measured displacements

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Laser Head

P-820 Actuator Tip and C-65

Accelerometer

Polytec Vibrometer


Actuator Test Verification and Validation

• Key Measurements: • Accelerometer data corresponding to 20 𝜇m vibration

• Vibrometer data corresponding to 20 𝜇m vibration

• Desired Results: • The accelerometer and vibrometer data will give consistent displacement

predictions

• Each method will show a 20 𝜇m displacement

• Impact of Results: • Verify that actuator meets requirement of displacement

• Verify that accelerometers measure vibrations


Full System Test • Requirements

• Test Stand shall produce EFT vibrations of 20𝜇m in amplitude, with varying frequencies of 40-60 Hz

-FR.1 → DRT.2: Cryocooler EFT’s can be imitated for testing

• Test Stand will support SAVI system above itself as a fixed structure -FR.3 → DRT.1, DRT.4: SAVI will support simulated camera payload

• Test Stand will measure residual vibrations using two piezoelectric accelerometers mounted on SAVI

-FR.5 → DRT.3: SAVI success is quantified by magnitude of residual vibrations

• SAVI will mitigate tip and tilt by 60% (Tier 1) and 80% (Tier 2) -FR.1, FR.2, FR.5

• Objective • To utilize accelerometer output for the purpose of verifying reduction in tip/tilt


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Full System Test Protocol

1. Setup system in the environment where the ambient noise is acceptable (determined by Ambient Noise Test) 2. Include Test Stand under SAVI structure and setup vibrometer from the Polytec/MEMS facility 3. Actuate test stand at 20 μm 4. Sense actuation with accelerometers and actuate SAVI 5. Verify amplitude reduction of structure with vibrometer


MATLAB Code

DAQ

Charge Amplifier

PDM Driver Actuator

Accelerometer

Vibrometer

Test Stand

SAVI

Full System Verification and Validation

• Key Measurements: • Residual vibrations in testing system’s accelerometers

• 2 piezoelectric accelerometers, placed on opposite ends of the top plate on SAVI • Both accelerometers will have same readings when no tip or tilt is present on top plate

• Residual vibration is the difference between the two accelerometers • Results are in mV

• Desired Results: • Tier 2 level of success will be met and conveyed by accelerometer data

• Difference in accelerometer signals will be approximately ±3 mVpp at 80% reduction

• Impact of Results: • Results will be analyzed using the same process SAVI uses to measure EFTs

• Voltage will be converted to acceleration and then to displacement • Maximum displacement and radial distance between accelerometer and center of plate will

calculate a maximum angular deflection of top plate in residual signal and thus number of pixels smeared

• Number of pixels smeared will quantify project success


76%

7%

17%

Electrical

Mechanical

Remaining Budget

Total Budget

Electrical 3800.38

Mechanical 320.15

Total 4135.38

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Remaining Budget $864.62


Electrical Budget Item Description Procurement

Status Item Cost Shipping Number Total Item Cost

PDm200 Piezoelectric Driver Received 230 30 3 720

P-820.20 Piezoelectric Actuator Received 646 28.17 3 1966.17

Laser and Goggles Received 119.90 15 1 134.90

P-176.50 Flexible Flexure Ordered 177 - 3 531

P-176.30 Magnetic Adaptor Ordered 33 - 3 99

P-176.10 Magnetic Adaptor Ordered 21 30 3 93

AE0505D16F Actuator MSR Demonstration Actuator Received 88 30 1 118

Vector Boards Circuit Board Received 19.84 0 2 36.98

BNC Panel Mount Received 2.30 0 7 16.10

Banana Tip Panel Mount Received 0.70 0 2 1.40

LEMO Push/Pull Surface Mount Received 17.85 0 4 71.40

Wire Header Purchased 6.29 - 2 12.58

TOTAL $ 3800.53


Mechanical Budget

Item Description Procurement

Status Item Cost Shipping Number

Total Item Cost

8”x8” Aluminum Plate 1½” Thick

Simulated Mass Received 71.12 - 1 71.12

Aluminum Rod Leg Struts Received 6.29 - 1 6.29

ABS Rod Flexures Received 2.26 - 5 11.30

8”x8” Aluminum Plate ¼” Thick

Base/Top Plates Received 14.80 - 6 88.80

10”x10” Aluminum Plate Base/Top Plates Received 20.28 40.95* 4 130.07

Loctite Epoxy Purchased 12.57 - 3 12.57

TOTAL $ 320.15

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*Shipping is totaled from all orders


Backup Slides

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Adhesive / Flexures

• Requirements • Removability

• Shear Strength > 69 kPa • Product ranges: 2-20 MPa

• All Loctite Super Glues have more than 20x needed shear strength

Flexures

• Requirements • Withstand 23 N in compression

• Critical force on flexure is 6055 N • Withstand 7 N in tension

• Yield force is 471 N • Maximum bending stiffness of

330 N-m/rad • Bending stiffness is 17 N-m/rad

• Factor of safety is so high that

we are confident with our design

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Adhesive

Flexure Test • Compression

• Requirement – flexures must be able to support 23 N force without failing • Requirement derived from DRM 2,4

• Measurement - pass/fail

• Tension • Requirement – flexures must not fail with a 7 N force applied

• Requirement derived from DRM 4 and DRE 1,2 • Measurement - pass/fail

• Moment • Requirement – flexures must not fail with 8 N-cm moment applied

• Requirement derived from PI p-820.20 Limitations • Measurement - pass/fail

• Requirement – flexures must deflect a minimum of 4.85 𝜇m with 8 N-cm moment applied • Requirement derived from minimum flexure stiffness need for actuation and

tolerance of machining • Measurement – angle deflection, then converted to deflection

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Compression

Tension

Moment

Date post:	28-Apr-2019
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