Variable damping impedance control of a bilateral telerobotic system

Damping and stiffness control in a telerobotic system allows the programmer to define the master and slave dynamics to suit a given task. Unfortunately, many requirements for good teleoperation produce conflicting choices of desired dynamic parameters for different tasks. It is proposed here that the master and slave damping and stiffness matrices be functionally dependent on sensed and commanded values of force and velocity, with no previous knowledge of the environment required. A strategy has been devised which provides better quality teleoperation under a variety of circumstances than is achievable with constant dynamics. Tracking in free space and along a surface by the slave can be maintained while impact forces are minimized with this strategy. The variable damping algorithm has been implemented on a 7-degree-of-freedom Robotics Research Corporation manipulator with position input from a 6-degree-of-freedom Kraft master hand controller, and tracking and impact performance is illustrated.