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Testing and Characterization 13-14 December 2007 Carnegie Mellon

Testing and Characterization 13-14 December 2007 Carnegie Mellon. Scarab Testing & Characterization. Carnegie Mellon 13-14 December 2007. Scott Moreland. Characterization. Mobility CG xyz, Static tip-over angles Drawbar Pull Side slope  lean (level) vs. baseline

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Testing and Characterization 13-14 December 2007 Carnegie Mellon

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  1. Testing and Characterization13-14 December 2007Carnegie Mellon Carnegie Mellon | 13 December 2007

  2. Scarab Testing & Characterization Carnegie Mellon13-14 December 2007 Scott Moreland

  3. Characterization • Mobility • CG xyz, Static tip-over angles • Drawbar Pull • Side slope lean (level) vs. baseline • Straight incline ascent, lowering CG • Obstacles: trenching, boulders, etc.. • Drilling • Gravity off-load Can enough thrust be produced? Resist torques? • Drill thrust/torque extremes simulation • Slopes Carnegie Mellon | 13 December 2007

  4. Vehicle Center of Gravity • Z CG Pose Dependent • X-Y CG Total Weight: 280 kg • Drill system mass/CG stand-in • ASRG used to center vehicle CG *low *nominal *high Carnegie Mellon | 13 December 2007

  5. Static Tip-Over Angles *low *nominal *high (values from tilt-table testing) Carnegie Mellon | 13 December 2007

  6. Side Slope • Side Slopes • Significant increase in traction while body leveling on side slopes • 25° cross slope results • 52% decrease in downhill slip • Important sources of beneficial effects (side hill lean) • Edging of wheels • Equalize wheel pressure distribution • Actively centering CG over track-base center • Traction and control Carnegie Mellon | 13 December 2007

  7. Side Slope • Side Slopes • Significant increase in traction while body leveling on side slopes • 25° cross slope results • 52% decrease in downhill slip • Important sources of beneficial effects (side hill lean) • Edging of wheels • Equalize wheel pressure distribution • Actively centering CG over track-base center • Traction and control Carnegie Mellon | 13 December 2007

  8. Straight Hill Ascent • Straight Ascent (pose vs. angle of refusal) • 25° incline tests: • refuse at high pose, ascends at nominal/low pose • Lowering CG through pose change promotes equal normal force distribution in wheels increases angle of refusal Carnegie Mellon | 13 December 2007

  9. Drawbar Pull • Tested at full vehicle weight, 280 kg • XY-CG centered • Rubber skid loader tires • 60 cm diameter • 17 cm tread width • Coarse Sand: • 160 kg pull • 0.57 vehicle weight • High Traction Cement • 240 kg pull • 0.85 vehicle weight Carnegie Mellon | 13 December 2007

  10. Obstacles • Trenching • 50 cm Trench capability • Wheel Diameter, 60 cm • Boulders • Periodic obstacles Carnegie Mellon | 13 December 2007

  11. Drilling • Nominal Drilling Test • Support 1 m drilling into OB-1 lunar regolith simulant with NORCAT system • Gravity Off-loading • Drill reaction forces simulated while under lunar g • Drill reaction forces • 350 N max. thrust • 30 Nm torque • 250 kg Earth  42 kg Lunar (gravity off-loaded) • 42 kg weight – 350 N thrust  6.0 kg Mass Reserve • Capabilities • Expanded wheel base resists high drill torques • Failures • Combined loading: Lunar gravity while drilling on slopes > 15°, leads to downhill slippage • Down hill force rapidly increasing with slope angle Carnegie Mellon | 13 December 2007

  12. Specifications Drill tower (upright): 2.2 m high stance, 1.6 m low stance Mass: 280 kg Weight: 460 N  2750 N  Nominal power: 200 W (driving), 380 W (pose change)  Idle power: 78 W Locomotion speed: 5.0 – 6.0 cm/s Track width: 1.4 m Wheelbase: 0.8 - 1.3 m Aspect ratio (track/wheelbase): 1:1 low stance, 1:2 nominal, 1:7 high CG height: 0.64m nominal stance, 0.60m low, 0.72m high Static pitchover: 42° nominal stance, 29° high, 45° low Static rollover: 53° nominal stance, 48° high, 55° low Maximum / minimum straddle: 57 cm, Belly contact Approach / departure angle: 105° nominal stance Wheel diameter: 60 cm Rim pull (single wheel): 2500 N Drawbar pull: 1560 N (medium-coarse grain sand) } with full drill system payload Carnegie Mellon | 13 December 2007

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