Nonlinear Robust Hybrid Control of Robot Manipulators

The success of a robot force and position (hybrid) control scheme relies very much upon its robustness against uncertainties such as unknown external disturbance or modeling errors in the description of robot, sensor and envirornment. In this paper we propose a new nonlinear robust hybrid control scheme for robot motion control. The control input consists of a nonlinear and a linear part. The nonlinear input decouples a robot dynamics and obtains a set of position and force equations in the hand or cartesian coordinate. The linear part applies the robust servomechanism theory to suppress position or force tracking error due to uncertainties. This nonlinear robust hybrid control scheme is applied to a two-joint SCARA-type robot, and simulation results demonstrate excellent robustness properties and satisfactory hybrid control even under severe modeling errors.