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Pasadena, California October 24-25, 2007 Contributors to the development effort: from IMTEC

TMT M1 Segment Support Assembly (SSA) Preliminary Design Review (PDR) Volume-4: WARPING HARNESS (See last slide for Revision History). Pasadena, California October 24-25, 2007 Contributors to the development effort: from IMTEC

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Pasadena, California October 24-25, 2007 Contributors to the development effort: from IMTEC

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  1. TMT M1 Segment Support Assembly (SSA) Preliminary Design Review (PDR)Volume-4: WARPING HARNESS(See last slide for Revision History) Pasadena, California October 24-25, 2007 Contributors to the development effort: from IMTEC RJ Ponchione, Eric Ponslet, Shahriar Setoodeh, Vince Stephens, Alan Tubb, Eric Williams from the TMT Project George Angeli, Curt Baffes, Doug MacMynowski, Terry Mast, Jerry Nelson, Ben Platt, Lennon Rodgers, Mark Sirota, Gary Sanders, Larry Stepp, Kei Szeto TMT Confidential The Information herein contains Cost Estimates and Business Strategies Proprietary to the TMT Project and may be used by the recipient only for the purpose of performing a confidential internal review of the TMT Construction Proposal. Disclosure outside of the TMT Project and its External Advisory Panel is subject to the prior written approval of the TMT Project Manager. * Note: HYTEC, Inc. merged with IMTEC Inc. in March 2007.

  2. Contents • Warping Harness Design/Analysis • Fundamental Approach & Architecture • Warping Harness Requirements • Opto-mechanical • Mechanical • Design Concept • Performance Analysis • Actuator arrangement • Surface correction • Derived Requirements for Components • Mechanical & Electrical Design • Quantization Error Estimate

  3. Warping Harness FUNDAMENTAL APPROACH & ARCHITECTURE

  4. Fundamental Approach & Architecture • Purpose: • Allow automated periodic correction of low order surface distortions: • Residual errors from polishing • Coating stress distortion • Seasonal fraction of thermal distortion • Segment positioning errors within the array (Focus and Astigmatism) • etc. • Fundamental Approach: • Extension of the Keck design • Re-figure the mirror by bending it in a controlled manner using whiffletree • Bending moments introduced into whiffletree by a set of moment actuators • Actuators are motorized, instrumented and tied into the M1CS • Architecture: • 21 whiffletree joints are fitted with moment-actuators • Lead screw pushes against an instrumented leaf-spring to create a moment • Stepper motor drives lead screw to permit automation Slide Repeated from PDR Vol-1

  5. Warping Harness WARPING HARNESS REQUIREMENTS

  6. System Requirements • Opto-Mechanical Requirements – per DRD • Correction of Prescribed Surface Distortions • Seven Pure Zernike Aberrations - Second & Third order terms • Amplitudes (imposed on a circumscribed circle 1.44m dia) • One additional combined case: • Max Combination of 7 pure Zernike cases x 100% • Structural load case only (flexure and joint loads). No optical performance requirement.

  7. System Requirements • Opto-Mechanical Requirements – per DRD: continued • Warping Harness Actuator:

  8. Component Requirements • Mechanical Requirements • Lifetime • Operates up to 10 times per night [DRD] • Assume the adjustment is 10% of 0-peak range (conservative) [TBC] • 365 nights per year for 50 years (conservative) • Cycles = (10 ops/night) * (10% of 10)turns/op * (365 nights/yr) * (50 yrs) = 18,250 • a very small number for a lead screw/stepper motor combination • wear should not be an issue, aging may be more of an unknown over 50 yrs • motor insulation, strain gauge attachment & encapsulation • Power Dissipation Requirement:<0.2 Watts during adjustment [per M. Sirota] • Power dissipation is sum of strain gage power and motor power: • Assume ~ 1 adjustment/hour [derived from 10/night, TBC] • All strain gages powered for duration of adjustment sequence based on wiring scheme, slide 45. • Assume 5 seconds adjustment time per axis * 21 motors = 105 seconds • Gage power =[ 21 * (V2/R) * t] = [21 * (102/350) * 105/3600] = 0.175 W time averaged • Each motor powered only during adjustment: • Assume 2 seconds ON time per motor, 21 motors, P < 15 W per motor • Motor Power = [ (21 motors) * (15w/motor)(2 sec/3600 sec)] = 0.175W time averaged • Total power dissipation = Pgage + Pmotor = 0.175 + 0.175 = 0.350W • Actuators to be vacuum compatible • Maintenance: • Motors replaceable in-situ in the event of failure. • Preventive Maintenance (PM) during segment re-coating change-outs

  9. Warping Harness DESIGN CONCEPT

  10. Indicates Applied Moments (Equal and Opposite) Design Concept • Each whiffletree has 4 pivots with 2 bending DOF each: • Gives 24 (3*4*2) available DOF for this 27-point WT based warping harness • 3 joints between small & large triangles, per whiffletree • 1 joint between moving frame and large triangle, per whiffletree • Analysis determines which of these actuators are useful

  11. Small Whiffletree Triangle Small Whiffletree Triangle Design Concept • Actuator Schematic • Stepper motor driven screw displaces end of leaf-spring • Strain gauge on leaf-spring provides feedback for motor control • Motors will be mounted on the large whiffletree triangles and to the moving frame Slide Repeated from PDR Vol-1 Axial Support Flexure Nut Screw Large Triangle WT Joint Flexure (sheet flexure not shown) Stepper Motor Strain Gauge Leaf-spring

  12. Warping Harness PERFORMANCE ANALYSIS

  13. Optical Performance Analysis • Opto-Mechanical Analysis Approach: • Assume: 1.44m regular hexagonal meniscus, 45mm thick glass ceramic • Influence functions for each actuator calculated using NASTRAN FEA • 27 point WT has 24 joints available for Warping Harness inputs • Previous work on 1.2m segment showed only 18 inputs were required to meet rqts. • See backup slide summarizing actuator effectiveness study • Mr at inner triangles and Mr at large triangles not effective for Zernike corrections • Mr at inner triangles eliminated • But packaging constraints lead us to retain two actuators on the large triangles • Orthogonal pair have been rotated 45 degrees in-plane • Unit load cases are imposed motion between leaf-spring and actuator • via thermal strain (moment magnitude ~1Nm) • Correction of Prescribed Surface Distortions • Sigfit Software – Adaptive Control Routine Used • Solves for linear combination of inputs to minimize RMS for each case (7) evaluated • Results Include • Characterization of optical surface before and after actuation • Actuator load requirements • Rod Flexure & Pivot loads

  14. Indicates Applied Moments (Equal and Opposite) Optical Performance Analysis • Performance Analysis Results • 21 Actuator arrangement adopted Slide Repeated from PDR Vol-1 Mx’’ & My’’ Large Triangles, 3ea (Only Mq required) Mx’ & My’ Outer Triangles, 6ea Mq, Inner Triangles, 3ea (Mr not required)

  15. Influence Functions My’’ Large Triangle Mx’ Outer Pivot My’ Outer Pivot Mx’’ Large Triangle Mq Inner Triangle WT-1 WT-2 WT-3

  16. Optical Performance Analysis Results • Focus Correction EXAMPLE: See Back-up slides for other aberrations Input = 600 nm PV = 1200 nm surface, RMS = 310 nm Corrected: PV = 84.1 nm surface, RMS = 16.5 nm Reduction Factor = 18.8 Corrected Input

  17. Optical Performance Analysis Results • Performance meets requirements • Corrected amplitudes and reduction factors Meets Requirements

  18. Warping Harness • Warping Harness Actuators • Leaf-Springs • Mirror Support Rod Flexures Loads • Pivot Loads DERIVED REQUIREMENTS FOR COMPONENTS

  19. Component Requirements • Derived Opto-Mechanical Requirements • Resolution: • Requirement of 0.1% (Implies +/-1000 steps full scale, min.) • We choose 2X this minimum value • Motors are 200 steps per revolution with 10 turns gives 2000 steps full scale • Lead Screw: • We choose 5mm travel and screw with 0.5mm lead. (2.5 microns/step) • Loads: • MINIMUM required moment output (Mmin) sufficient to perform required corrections • REQUIRED OUTPUT (Mreq = 1.05* Mmin) • Hard-Stops: Hard-stops set outside operational range • We choose an additional +/-1.5mm of travel: Hard Stop = +/-6.5mm nominally • 0.5mm for Assembly and mfg. tolerances in whiffletrees (triangle tip/tilt & piston misalignment) • 0.5mm for WH components mfg, assembly and initial positioning error • 0.5 mm for Compliance of other parts in the system consume stroke • 0.125mm dead-band (lead-screw backlash) • Note that actuator may become temporarily jammed if it hits hard stop • hence, we want them out of the operational range

  20. Component Requirements • Design Load Calculation Methodology • 21 WH actuator unit cases in FE model • DT on actuator screw element produces a known WH moment • Calculate 1. Surface deformation, 2. Loads at actuators, rod flexures, and pivots • Perform Zernike Correction Simulation • Start with specified Zernike errors • Correct using linear comb. of 21 actuators (minimize surface RMS) • Back-Calculate Actuator, Rod Flexure, and Pivot Loads from actuation • 8th load case calculated: • Simultaneous correction of seven Zernike cases (absolute summation) • Interested in WH Actuator Loads (will discuss rod and pivot loads elsewhere) Unit Load Matrix 60 x 21 (60 FEA results by 21 load cases) Actuator Matrix 21 x 7 (Act. Correction Matrix: 21 Actuators Factors by 7 Load Cases) Component Loads 60 x 7 Unit Load Matrix 60 x 21 Actuator Matrix 21 x 7 x = Expanded Component Loads 60 x 8 (60 results {actuator, rod, pivot} by 8 load cases)

  21. Actuator Requirements • Design Load Calculation Methodology, cont. • Expanded Component Loads Matrix gives Actuator Load requirements • Mmin (from Simultaneous Zernike Correction Case) Min Moments

  22. Actuator Requirements • Design Load Calculation Methodology, cont. • Add 5% margin then round up to nearest 0.5 Nm  gives Mreq • Packaging constraints produce two actuator geometries: • Type-1: At 3-Inner Triangles: 190 mm long leaf spring • Mreq = 7.00 Nm, Force = 37N • Type-2: At 18-Other locations: 120 mm long leaf spring • Mreq = 9.50 Nm, Force = 79N • Required actuator force output: 79N (Operating)

  23. Component Requirements • Rod Flexure and Pivot Loads • Two design cases for Warping Harness • Simultaneous Zernike Correction Case • Extracted from the Expanded Component Loads Matrix (Slide 21) • Simultaneous actuator runaway against hard-stop (controller malfunction) • Unit Load Matrix scaled to Hard-Stop actuator load levels (absolute summation)

  24. Warping Harness • Moment Actuator System • Linear Actuator • Instrumented Leaf Spring • Wiring & Connectors MECHANICAL & ELECTRICAL DESIGN

  25. Moment Actuator System • Whiffletree Moment Actuator: • Linear Actuator pushing on Leaf Spring: • Linear actuator: • Stepper motor driven lead screw (0.5mm pitch) • NEMA-17 Stepper Motor, 30 oz-in holding torque [TBC by Dev. testing] • Stall-Torque Margin > 100% [TBC Derived Requirement) • Flexible leaf spring • Instrumented with strain gauge • Low cost components (>12,000 assemblies required): • Testing required to verify performance & reliability • Two moment actuator types: • Inner Triangle: 190mm Spring, M = 7.0 Nm (3 per segment) • Other Locations: 120mm Spring, M = 9.5 Nm (18 per Segment) • Same Linear Actuator used in each location, two leaf spring types: • Capable of producing 79 N force

  26. Typical Warping Harness Moment Actuator: Moment Actuator System Leaf Spring Inner Triangle Large Triangle Whiffletree Joint, typical Actuator

  27. Linear Actuator • Linear Actuator Design: • Produces >79N force • Resolution better than 0.1% • 5mm * (1 rev/0.5mm) * (200 steps/rev) = 2000 steps 0-peak (0.05% nominally) • Modular design • Built and tested as sub-assembly • Motors replaceable in-situ • Internal hard-stops to prevent over-driving • +/- 6.5 mm Stroke (Between hard-stops) • Dead-band • 0.125mm thrust clearance built into screw/nut combination • Low cost components • Vacuum compatible [Specific requirement TBD ] • Vacuum grease in motor bearings • Low out-gassing materials • Clean • Lead screw enclosed to keep mechanism clean • vented for vacuum

  28. Linear Actuator • Linear Actuator Design: Dust cap Bellows – Dust Seal Baseplate Actuator Leaf Spring Motor Mount (Extrusion) Stepper Motor NEMA-17 30 oz-in Whiffletree Triangles Hand-knob

  29. Linear Actuator • Linear Actuator Design: Shaft Bearing Set: Bushings (Rulon LR) Thrust Washers SST Snap rings Extruded Alum. Motor Mount Drive Nut 360 Brass Stepper Motor Outer Hard Stop Snap-ring + Washer Flexible Shaft Coupling Leaf Spring Capture Nut Drive Screw (Stainless Steel) Lubricated with Krytox GPL 216 MoS2 filled vacuum grease

  30. Linear Actuator • Linear Actuator Design: Retracted Against Hard Stop Neutral Position Extended Against Hard Stop

  31. Linear Actuator • Linear Actuator Design: • Motor Removed 6 ea Access holes for coupling clamp Screws

  32. Stepper Motor Specification • Stepper Motor Specs • Vendor: TBD; Model: HT17-30 • NEMA 17 standard mount • 30 oz-in (212 N-mm) of holding torque • 1.8° step angle (200 per rev) • Coil current: 1.3 A • Detent torque: 5 Nmm • Dimensions: • Height: 33 mm • Width: 42 mm • Shaft: 5 mm  • Mass: 194 g • Vacuum grease, low out-gassing materials and bake-out required • Considerations: • low inductance will reduce transients during multiplexing

  33. Linear Actuator • Linear Actuator Design: • Actuator Design Calculations – Type-1: Inner Triangle Locations

  34. Linear Actuator • Linear Actuator Design: • Actuator Design Calculations – Type-2: Other Locations

  35. Linear Actuator • Linear Actuator Design: • Hard-stop design loads (a function of friction) • Worst Case Analyzed: Low friction results in large hard-stop loads: • Screw Friction 0.1 Thrust Washer Friction 0.05 • Max Hard-stop load on Type-1 actuator: 243N • Shaft Stop (E-ring) reacts actuator force • E-ring strength = 289N • Factor of Safety = 1.2 Outer Hard-stop

  36. Instrumented Leaf Springs • Leaf Spring Design Requirements • Two types: 190 mm and 120 mm long • Strokes: • 5mm operational • 6.5mm at hard-stop • Strain gauge for feedback: • resolution 0.1% of full scale • calibrated • Material: Aluminum 7075-T651 per AMS QQ-A-250/12 • Match CTE of whiffletrees • Yield Strength = 69 ksi (476 MPa), Ultimate Strength = 80 ksi (552 MPa) • Considerations: • Stress: • Desire a high, uniform strain field at gauge location • Minimize stress elsewhere • Beam and gauge fatigue life (>100,000 cycles) • gauge thermal compensation • Cost

  37. Instrumented Leaf Springs • Leaf Spring Concept: • Re-entrant tab tuned to produce zero slope at drive screw • Prevents binding at drive screw • No additional spherical bearing required - low cost, simple Note: Deflection Exaggerated 10X

  38. 120 mm Instrumented Leaf Springs • Bending-beam transducers • gauge locations as shown (one side only) Type-2 Leaf Springs 5.80 mm thick – made in orthogonal pairs Type-1 Leaf Springs 6.70 mm thick 190 mm

  39. Instrumented Leaf Springs • Leaf Spring Concept: Type-2 (Other locations) • Deflection, Slope, and Stress Results: Deflection, mm F=102.9N Deflection: 6.5mm at drive screw Hard stop displacement Slope, rad. Slope: 0.33 mrad At drive Screw von Mises Stress, MPa Stress: 261 MPa (38 ksi) at Hard-stop FSy = 69/38 = 1.81 Deflection Exaggerated 5x

  40. Instrumented Leaf Springs • Strain Gauge Location • Beam root necked-down and tapered to shape stress field: • High, uniform stress field preferred for gauge resolution and lifetime • Vishay recommends <1700 micro-strain for 1E6 fully reversed cycles (100me shift) • We relax by 1.5x to <2550 micro-strain for our design (<1E6, and rarely reversed) Type-1 (Inner Triangle) Longitudinal Strain at Gauge Location ex = 1513 me at 6.5mm deflection Type-2 (Other Locations) Longitudinal Strain at Gauge Location ex = 2276 me at 6.5mm deflection Gauge Location Gauge Location Axial Strain m/m Axial Strain m/m

  41. Instrumented Leaf Springs • Leaf Spring Stress, Strain, FOS Summary

  42. 4 3 1 2 Signal Signal +VIN -VIN C B A D Instrumented Leaf Springs • Strain Gauge • Bending-beam transducer: Full Poisson Bridge • Vishay JA2-13-S1425-35B • 5.64mm x 6.66mm • Bending strain amplified by Poisson effect • Inherently temperature compensating • Gauge CTE matched to leaf spring material • Gauge installation by transducer manufacturer: • Gauge bonding, lead attachment, encapsulation, strain relief & connectorization • Calibration • each beam has engraved S/N and barcode sticker • calibration results entered into database • Strain Gauge heat dissipation • P = V2 / R = (10V)2 / 350W = 286 mW/bridge • Need to investigate on/off transient of gauges • what is time constant for stable reading • 12,000 gauges x t may be significant if serial op. • 12,000 * 286 mW also significant (3.4KW) • Heating and timeline must be balanced • Will investigate (literature, experts, prototypes)

  43. Strain Gauges • Summary of Predicted Strain Gauge Performance: • See backup slides for supporting calculations • Required resolution (0.1%) corresponds to 2 steps: • Type 1 Leaf Spring output is 16.26 mV (for 10 V excitation) • Type 2 Leaf Spring output is 27.68 mV (for 10 V excitation)

  44. 4 3 1 2 Signal Signal +VIN -VIN C B A D Wiring & Connectors • Warping Harness Wiring and Connectors • Stepper motor windings connected in series (max low speed torque) • Winding splice and connectorizing performed by stepper motor supplier • 4 wires per motor • 2 of which are common to all 21 motors • say -A and -B • 2 of which are unique (switched to driver) • say +A and +B • Strain Gauges have 4 leads each • 2 leads are common to all gauges (A & C) • 2 output signals are unique for each gauge (B & D)

  45. Strain Gauge Wiring • Warping Harness Wiring and Connectors • 44 pins/segment • Type-1 Leaf Spring requires one 4 pin connector: • 1 strain gauge bridge per assembly • Type-2 Leaf Spring requires 6 pin connector • 2 bridges/assembly ( 2 common, 4 gauge signal) 21 Warping Harness Gauges per Segment +Vin 2 Common Inputs -Vin WH-1 WH-2 WH-3 WH-4 WH-5 Signal-1 Signal-2 Signal-3 Signal-4 Signal-5 Signal-1 Signal-2 Signal-3 Signal-4 Signal-5 2 x 21 Outputs = 42 channels 44 pins required for strain gauges

  46. Stepper Motor Wiring • Stepper Motor Wiring and Connectors • 44 pins/segment Common A WH-1 Phase-A Phase-A Phase-A Phase-A WH-2 WH-3 WH-4 Phase-B Phase-B Phase-B Phase-B Common B 2 x 21 Inputs = 42 channels from relay panel 44 pins required for stepper motors

  47. Stepper Motor Wiring • Warping Harness Wiring and Connectors • Layout: • 44 pins for strain gauges • 44 pins for stepper motors • 2 pins for segment serial number communication I/O • 1 ground pin • 89 TOTAL PINS • Connector types and models TBD 89 pins required

  48. Stepper Motor Wiring • Warping Harness Control Layout – 3 of N Segments Shown 44 wires 44 wires 44 wires Segment-i Segment-j Segment-k 21 Strain gauges 21 Stepper motors 21 Strain gauges 21 Stepper motors 21 Strain gauges 21 Stepper motors 44 wires 44 wires 44 wires WH Control Node (Supports N segments) Cell Mounted Stepper Relay Box Stepper Driver (Single Axis) DAQ Strain Gauge Relay Box Processor/Communication/Power supply M1CS Power Coolant

  49. SSA Wiring Connector Bulkhead Panel

  50. SSA Wiring Connector Bulkhead Panel

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