Robot Arm (RA) and Camera (RAC)





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The Phoenix RA will dig a trench up to one meter deep and acquire samples for TEGA and MECA; RAC will document the trench and acquired samples.

Design & Implementation: The RA and RAC were delivered to the MSP'01 project and are in bonded stores at JPL. The RA is a 2 m. long, 4 degree-of-freedom (DOF) device constructed of graphite-epoxy links and aluminum joint housings. Joint actuators are heated DC motors with 2-stage drive trains. The typical end-effector force is 80N. The ripper tines used for the MVACS Mars ‘98 scoop will replace the M‘01 scoop blade. An 8051 processor provides low-level motor and heater commands, monitors state sensors and provides reflex current limiting/shutdown control.  Trajectory generation, motion control, telemetry, and fault management is handled by the Lander computer. A 12-bit A/D converter processes sensor signals.  The RAC attaches to the wrist of the RA. One motor moves the focus from 10 mm to infinity, while a second opens and closes a transparent dust cover. RAC magnification is 1:1 at closest focus. LEDs provide 3-color illumination forcolor images. Viewing the same scene from two orientations provides stereo imaging. An electronicscard in the Payload Electronics Box drives both RAC and the MECA microscope.

Operations: Trenching is guided by the SSI DEM and by RAC stereo images. Samples will be obtained by scooping small portions of the trench bottom, using RAC images to guard against contamination from cave-ins. The RAC will image all collected samples (as part of TEGA and MECA documentation), the soil at the tip of the scoop, close-up views of the dump pile, and walls of trenches deeper than 20 cm. Attempts will be made to move nearby rocks with the RA and examine their surface textures with RAC. The RAC can also act as a stereoscopic camera with 2 mrad/pixel resolution.