1. Dave Akin, Lockheed Martin AKIN@LMSAL.COM 650-424-3989
HMI Mechanisms
Dave Akin, Lockheed Martin
Revision K

2. HMI Mechanisms Hollow-Core Motors (7 motors) Shutters (2 motors)
Each motor rotates an optical element
Shutters (2 motors)
One for each CCD
Control exposure to CCD
Focus Wheels (2 motors)
Adjust focus by placing various thickness glass into optical path
Calibration mode places 2 lenses into optical path
Front Door (2 motors)
Open and close aperture door
Alignment Mechanism (2 motors)
Move (point) instrument with respect to spacecraft

3. HMI Mechanism Locations

4. Hollow-Core Motor Requirements
Design Life (5-year mission): 80 M operations
Repeatability: 20 arc-seconds (1 sigma)
Absolute Stopping Accuracy: ±8 arc-minutes
Clear Aperture: > inches (34 mm)
Operating Temperature: 15 to 35 C
Survival Temperature: -10 to 50 C
Time to Move: 180 degree move in 1 second

5. Similar Motor from Program D

6. Hollow-Core Motor Section
RED = ROTATING PARTS

7. Hollow-Core Motor Design
Motor: H.Magnetics Brushless DC Motor
Bearing: MPB Size S2532
Lubrication: Nye 2001B (vacuum impregnated)
Retainer: Phenolic, one-piece
Preload: Back-to-back matched pair; 10 – 15 lb.
Mass: < 500 g
Energy dissipated by Hollow-Core Motors (Joules):
Windings: * degrees moved
Encoder: * degrees moved
Total: * degrees moved
(results of computer simulation)
Torque
34 oz-in available (stall)
Bearing Friction: < 2 oz-in
Magnetic Detent: TBD (1 to 6 oz-in, based on prototype testing)
Hysteresis Drag Torque: < 1 oz-in

8. Hollow-Core Motor Testing
Prototype
Operate with 2 different rotors
Skewed magnets
Like Program D motor
Minimal magnetic detent
Straight magnets
Unknown magnetic detent
Reduced eddy current losses
Pick design with best repeatability
Operate motors in thermal chamber (-20 to 60 C)
Repeatability test with external encoder (all positions)
Repeatability test with theodolite (fewer positions, higher resolution than encoder)
Torque margin verification (operate with reduced voltage)
Friction & Cogging (measure with torque watch)
Measure disturbance torque vs. time
Measure Resistance, BEMF (Back ElectroMotive Force) , Damping and Friction Coefficients
IRED (Infrared Emitting Diode) intensity margin

9. Hollow-Core Motor Testing
Flight Motors
Repeatability test with external encoder (all positions)
Torque margin verification (operate with reduced voltage)
Friction & Cogging (measure with torque watch)
Measure Resistance, BEMF, Damping and Friction Coefficients
IRED intensity margin

10. Hollow-Core Motor Life Test
5-year expected use is 80 M operations
Vacuum life test 2 identical motors to minimum 160 M operations each
Life Test Motors:
Assembled using detailed assembly procedures (same as used for flight motors)
Functional Tests (same as flight motors)
Vibration (GEVS level)
(GEVS = GENERAL ENVIRONMENTAL VERIFICATION SPECIFICATION FOR STS & ELV PAYLOADS, SUBSYSTEMS, AND COMPONENTS)
Thermal (-10 to 50 C in air)
Vacuum Life Test
Temperature held at 30 C with heaters
Mechanism health is trended throughout the test
Disassemble & Inspect
Refurbish to become Flight Spares (new bearings)

11. Hollow-Core Motor - Heritage
MDI Michelson Tuning Motors
Single, Magnetically Preloaded Bearing
TRACE Guide Telescope Motors
Identical to MDI Tuning Motors
Program D Polarization Modulator
Similar Bearing Design (slight size difference)
Same Lubricant, Same Retainer
Program F Hollow-Core Motor
Braycote 600, Teflon Toroids

12. Focus Wheel Requirements
Design Life (5-year mission): 2 M Operations
Operating Temperature: 15 to 25 C
Survival Temperature: -10 to 50 C
Optical Beam Diameter: 1.004” (25.5 mm)
Optical Elements:
Wheel 1 Wheel 2
Blank Position Blank Position
10.2 mm thick focus block 2.55 mm thick focus block
6.8 mm thick focus block 1.7 mm thick focus block
3.4 mm thick focus block 0.85 mm thick focus block
6.8 mm thick lens 5 mm thick lens

13. Focus Wheel Design 5 positions per wheel
Order of optics in wheels selected for best balance
Wheels are not otherwise balanced
1.190” Diameter Opening
Bearings
Timken MPB SR4FCHH7
Lubricant: Braycote 600 Grease
Preload: 3 lb.
Mass: < 300 grams
Torque
20 oz-in available (stall)
Bearing Friction: < 1 oz-in
Magnetic Detent: ~ 6 oz-in
Hysteresis Drag Torque: < 1 oz-in

14. Filter Wheel

15. Focus Wheel Layout

16. Focus Wheel Testing Prototype Flight
Operate in thermal chamber (-20 to 60 C)
Repeatability (external encoder)
Torque margin verification (operate with reduced voltage)
Friction & Cogging (measure with torque watch)
Measure disturbance torque vs. time
Measure Resistance, BEMF, Damping and Friction Coefficients
IRED intensity margin
Flight

17. Focus Wheel - Heritage MDI TRACE Program C Program B Program E
68 M operation vacuum life test without failure
3 wheels functioning without failure in the MDI instrument since 1995
TRACE
5 ½ years of on-orbit operations without failure
Program C
32 M exposure vacuum life test without failure
4 filter wheels are integrated to 2 flight SXI instruments
Program B
Prototype filter wheel has undergone thermal & vibration testing
2 flight filter wheels are integrated to the flight instrument
Flight instrument has undergone environmental testing
Program E
2 wheels are integrated to the flight instrument; testing is in-progress
Program D
4 wheels are integrated to the flight instrument; testing is in-progress

18. Shutter Requirements Design Life: 40 M Exposures
Operating Temperature: 15 to 25 C
Survival Temperature: -10 to 50 C
Performance Requirements:
Minimum exposure: 50 ms
Nominal exposure: ~250 ms
Maximum exposure: 10 s (for LTC and darks)
Exposure Measurement Resolution: 2 μs
Repeatability: 10 μs standard deviation (one sigma)
Uniformity: 250 μs (across field of view)

19. Shutter Design Motor: Kollmorgen RB-00502-N02
Bearing Design is TBD (based on outcome of life test)
Baseline Design: Nye 2001B lubricant
Phenolic retainer
0.9 lb. spring preload
Mechanical design is similar to Program D shutters
Thicker encoder housing for radiation shielding
Energy:
Joules per exposure = * exposure in seconds (computer simulation)
Mass: ~125 grams (motor & blade)
Torque
2.44 oz-in available (stall)
Bearing Friction: < 0.2 oz-in
Magnetic Detent: ~ 0.5 oz-in
Hysteresis Drag Torque: < 0.2 oz-in

20. Shutter Section
RED = ROTATING PARTS

21. Shutter Motor Exploded View
RED = ROTATING PARTS

22. Shutter Operation Clockwise Operation Shown 2 Moves for each exposure
120 degree move to open
240 degrees to close

23. Shutter Testing Prototype Flight
Operate in thermal chamber (-20 to 60 C)
Exposure repeatability test
Torque margin verification (operate with reduced voltage)
Friction & Cogging (measure with torque watch)
Measure disturbance torque vs. time
Measure Resistance, BEMF, Damping and Friction Coefficients
IRED intensity margin
Flight

24. Shutter Performance Testing
Prototype HMI Shutter
1000 Consecutive Exposures
ms Exposure Setting
Vary Voltage from 14.9 to 15.0 every 100 exposures
14.9 V
15 V

25. Shutter Life Test 5-year expected use is 40 M exposures
Life test 4 shutters:
Lubricant Retainer Preload Bearing
1) Bray 815Z Crown lb. SR3FCHH7P28LY303
2) Nye 2001B Phenolic lb. N (custom)
3) Nye 2001B Phenolic lb. N (custom)
4) Nye 2001B Minapore lb. N (custom)
80 M exposure (each shutter) life test:
Assemble using detailed assembly procedures (same as used for flight motors)
Functional Tests (same as flight motors)
Thermal (-10 to 50 C in air)
Vibration (GEVS level)
Vacuum Life Test
Temperature held at 30 C with heaters
Mechanism health is trended throughout the test
Disassemble & Inspect Bearings

26. Shutter Heritage SXT MDI TRACE Program C Program B Program F Program E
In orbit since 1991
8 M on-orbit exposures without failure
MDI
68 M operations without failure (vacuum life test)
~ 70 M on-orbit operations without failure
TRACE
12.5 M on-orbit exposures without failure
Program C
33 M operations without failure (vacuum life test)
2 Shutters integrated to 2 flight SXI Instruments
Program B
Shutter integrated to flight instrument; undergone environmental testing
Program F
Life test in progress
Program E
Integrated to the flight instrument; testing in-progress
Program D
2 Shutters integrated to the flight instrument; testing in-progress

27. Door Requirements
Mechanism must open the door with any plausible single-point failure
Door Opens 170  5 Degrees
Design Life: 1000 Cycles
Operates in Any Orientation in 1G
Operating Temperature: 0 to 40 C
Survival Temperature: -20 to 65 C

28. HMI Door

29. Door Assembly

30. Door Design Spring to hold door shut: Actuator: Lubricants:
SPEC T R
1.5 in-lb closed
2.9 in-lb opened
Actuator:
Made by CDA Intercorp
Torque: 6 lb-in (50:1 gearhead, 100 pps)
12 steps per motor revolution
600 steps per worm revolution
11,333 steps to open door ( pps)
Lubricants:
Actuator Gearhead: Braycote 600
Worm & Wheel: Pennzane Grease

31. Door Operation One motor is normally used to open/close the door.
Nothing prevents both motors from being used at once.
Each motor operates independently from the other.
Motor runs until either:
a) Limit switch is activated
b) Programmed maximum number of steps have been sent
Drive electronics stores the number of steps required to open or close the door.
There are override commands in case a limit switch fails closed.
Door can function with either a failed-open, or failed-closed limit switch.
Door may be opened to less than the nominal 170 degrees.

32. Door Testing Brassboard Mechanism Flight Mechanism
Various Functional Tests
Torque Margin Verification
Operate in Thermal Chamber (-20 to 70 C)
Vibration with Structural Model
Flight Mechanism
Environmental Tests with Flight Instrument

33. Door Heritage Similar to MDI Door Differences:
Either Motor Can Open Door
Spring Holds Door Closed
Door is Balanced
Differences:
HMI uses Step Motors from CDA Intercorp
MDI used Brushless DC Motors from Inland Motor
HMI uses CDA Gearhead (integral with motor)
MDI used Gearhead from PIC

34. Alignment Mechanism Requirements
On-Orbit Range: ± 200 arc-seconds
Range for Ground Testing: ± 600 arc-seconds
Step Size: 2 arc-seconds maximum
Design Life: 1 M steps
Operating Temperature: 0 to 40 C
Survival Temperature: -10 to 50 C

35. Alignment Mechanism Design
Actuator:
Made by CDA Intercorp
Maximum Operating Force: 10 lb.
Maximum Non-Operating Force: 250 lb.
12 steps per motor revolution
25:1 Gearhead Ratio
Step Resolution: inches
Lubricants:
Actuator Gearhead: Braycote 600
Leadscrew: Braycote 600
Position Feedback:
Each lever has a 2-channel optical encoder
One channel indicates if the mechanism is within its operating range
Other channel indicates which half of the range the mechanism is in

36. Alignment Mechanism

37. Alignment Mechanism

38. Alignment Mechanism

39. Alignment Mechanism

40. Alignment Mechanism Range

41. Alignment Mechanism Testing
Brassboard Mechanism
Various Functional Tests
Torque Margin Verification
Vibration with Structural Model
Flight Mechanism
Environmental Tests with Flight Instrument

42. Alignment Mechanism Heritage
Similar to MDI Alignment Mechanism
Differences:
HMI uses step motors from CDA Intercorp
MDI used Kollmorgen motors
HMI has gearhead between leadscrew & motor
MDI had motor directly drive the leadscrew
HMI uses optical sensor for position feedback
MDI used microswitches & potentiometers
Optical limit switch
Same electronic parts as other encoders
Same design as:
TRACE Focus Mechanism
Program D Slit Scan Mechanism

43. Disturbance Torque Focus Wheel Hollow-Core Motor Shutter Front Door
40 oz-in (computer simulation)
Hollow-Core Motor
15 oz-in (computer simulation)
Shutter
3 oz-in (computer simulation)
Front Door
Disturbance < 2 oz-in
Mechanism is seldom used
Alignment Mechanism

44. Summary Peer review held 9/17/2003 Hollow-Core Motors Shutters
Received comments from Ken Lee & John Van Blarcom (NASA) as well as from several Lockheed Martin participants
Hollow-Core Motors
Prototype motor on-order; expected 11/25/2003
Life test planned to start spring 2004
Shutters
One for each CCD
Life test planned to start January 2004
Focus Wheels
Detailed drawings in-process
Front Door
Alignment Mechanism
2 actuators on-order (due 3/10/2004)