REDUNDANCY CONTROL OF A FREE-FLYING TELEROBOT

Manipulation from a free-flying vehicle has applications in space and undersea teleoperation. Both environments allow a vehicle to move freely in all six degrees of freedom. For many operations, such as inspection and servicing, the ability to manipulate from an undocked teleoperator will be essential. The major contribution of this research is the development of a control algorithm, coordinated control, which allows the simultaneous reduced-order control of a vehicle and attached manipulator/The entire telerobot system is controlled by commanding the end effector inertially with respect to the task. This is accomplished through a unified treatment of the vehicle and manipulator as a single dynamic system, based on considering the free-flying teleoperator as a redundant manipulator. The vehicle controller minimizes fuel expenditure while maintaining a desirable manipulator configuration. The coordinated trajectory algorithm is a blend of two modes: gradient pseudo-inverse trajectory control, which uses both vehicle thrust and manipulator motion, and reaction-compensation trajectory control, which allows the base to react freely to manipulator interaction torques. Blending between these modes occurs as a function of the teleoperator's configuration potential. The potential incorporates kinematic functions such as singularity avoidance, joint limits, and collision avoidance. © 1990 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.