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2. 2. COORDINATED MOTION (CONTROLLING TIP) CHOICE OF COORDINATE FRAMES • TIED TO ORBITER THC - in, TIP of arm → RHC - pitch, TIP PITCH (in orbiter frame) THC/RHC COMMAND RATES (max 2 ft/sec): CMD → GPC → (algorithm to resolve) into CMDs for each joint → CMDS TO JOINT (6 DEG of FREEDOM) • TIED TO END OF ARM (SITTING ON CAMERA) USED DURING REL/CAPTURE: EYES GLUED TO TV MON (EE CAMERA) → FLYING THE CAMERA → (PROBLEMS INVOLVED IN DESIGNING SOMETHING MECHANICAL ON SHUTTLE) (WILL SEE IN VIDEO) [WEIGHTLESS] (THINGS ARE WEIGHTLESS: GOOD NEWS + BAD NEWS) GOOD: CAN LIFT ANYTHING (ELECTRIC MOTORS, HOLLOW BOOMS → 950lbs) [[left margin]] (10) [[/left margin]] BAD: CAN'T TEST IT THOROUGHLY ON GROUND -CAN'T SUPPORT WT -CAN'T TEST WTLESSNESS → DON'T KNOW (MEASURE) SYSTEM FLEXIBILITY MODES ([[x y?]]) COUPLING BETWEEN MODES → UNCERTAINTY ABOUT PERF. IN ORBIT (DYNAMICS) + HOW ASTRONAUT WILL EXCITE DYNAMICS (1) PROBLEM FOR SYSTEM VERIFICATION (COMPUTER SIM) (2) CREW TRAINING [NO REAL ARM SEVERAL SIMULATORS + TRAINERS TO GET PIECES] --------- [SES] 3 SIMULATORS • SMS (COMPUTER GEN. VISUALS LOOKS LIKE SHUTTLE COCKPIT) (BAD DYNAMICS) • SIMFAL (GOOD DYNAMICS, LINE DRAWINGS [[)]] • MDF (PRACTICE CONTROLLING SOMETHING 50' long THAT CAN BREAK THINGS)