Adaptive robust control of underactuated robot manipulators

Summary form only given as follows. A study on the control of robot manipulators with passive joints overcoming actuator failures is performed. An adaptive robust control scheme of underactuated robot manipulators using the brakes equipped at the passive joints in joint space is proposed using the dynamic coupling in the presence of parametric uncertainty and external disturbances. The proposed control scheme has two control stages, the passive joint control stage and the active joint control stage. It is assumed that the passive joints do not have actuators but have brakes in this case. Note that all the passive joints are locked by their own brakes as soon as they reach their desired set-points with zero velocity. In the other case that the passive joints have neither actuators nor brakes, an adaptive robust control scheme overcoming the uncertainties is also proposed in Cartesian space where tasks are planned. To overcome the dynamic singularity problem in the controller, a singularity-free desired Cartesian path-planning within the inside of the nonsingular regions is achieved based on a computer simulation. To illustrate the feasibility and validity of the proposed control schemes, simulation results for a three-link planar robot manipulator with a passive joint are presented.