A FREQUENCY-DEPENDENT DIRECT ADAPTIVE SCHEME FOR ROBOT MANIPULATORS -A CASE OF MODEL-FOLLOWING MOTION CONTROL

This paper presents a new frequency-dependent direct adaptive scheme f or the optimal and/or suboptimal tracking of the motion of a prescribe d model. The idea is based on a closed-loop control scheme in which an H-2 optimal/suboptimal controller is applied in parallel with a direc t adaptive technique to guide a robot manipulator to follow a certain prescribed trajectory. The H-2 compensators have to be proper and posi tively bounded with respect to all dynamic frequencies. Robustness iss ues are addresses in the paper by lumping all the nonlinear dynamic te rms such as the centrifugal and Coriolis effects as well as the mechan ical and electrical friction forces of the robot arm, into a general u nstructured uncertainty term.