Human Operator Control of a Bilateral Teleoperator in Part-Simulation of Zero Gravity

Abstract

An experimental investigation has been undertaken at the Jet Propulsion Laboratory to address issues associated with manual control of a teleoperated manipulator operated in an earth orbital environment (e.g., the Shuttle Remote Manipulator System (RMS)). Manual control of a teleoperator and the effect of microgravity on the operator's performance were examined using a force-reflecting hand controller (FRHC) and a gravity compensation system to simulate the effect of microgravity on the operator's arm. The kinematic and dynamic characteristics of the operator's arm and hand play a fundamental role in bilateral (backdriven) teleoperator control. Two control experiments were performed in this study: (a) verification of a linear damped harmonic oscillator model of human neuromotor control in trajectory formation and stability in standard one gravity (lg) operation, and (b) force tracking along simulated planes of resistance subject to unit pulse disturbance in simulated zero g operation. The results of the experiments verified the utility of the neuromotor model in teleoperator control performance and confirmed the existence of disturbance of human manual control performance associated with the micro-gravity condition. The results illustrate that compensatory techniques to return performance to a level commensurate with, or superior to, standard one gravity operation could be derived. These techniques are based on the human control model, and instituted through FRHC control parameter adjustment.