Performance evaluation of a six-axis generalized force-reflecting teleoperator

Recent work at JPL in real-time distributed computation and control has culminated in a prototype force-reflecting telemanipulation system having dissimilar master (cable-driven force-reflecting hand controller) and slave (PUMA 560 robot with custom controller), extremely high sampling rate (1000 Hz), and low loop computation delay (5 msec). In a series of experiments with this system and five trained test operators covering over 100 hours of teleoperation, we measured performance in a series of generic and application-driven tasks with and without force feedback, and with control shared between teleoperation and local sensor referenced control. Measurements defining task performance include 100-Hz recording of six-axis force/torque information from the slave manipulator wrist, task completion time, and visual observation of predefmed task errors. The tasks consisted of high precision peg-in-hole insertion, electrical connectors, velcro _.t tach-de-attach, a.nd a twist-lock multi-pin connector. Each task was repeated three times under several operating conditions: "normal" bilateral telemanipulation, forward position control without force feedback, and shared control. In shared control, orientation was locally servo controlled to comply with applied torques, while translation was under operator control. All performance measures improved as capability was added along a spectrum of capabilities ranging from pure position control through force-reflecting teleoperation and shared control. Performance was maximal for the bare-handed operator.