Adaptive Hybrid Force/Position Control of Multi-Dimensional Position Controlled Robots: Theory and Experiment

|This paper addresses the problem of achieving exact dynamic hybrid force/position control with multidimensional manipulators possessing the low level position controllers typically employed in industrial robot arms. Previously reported approaches and experimental results are reviewed. A new adaptive hybrid force/position control algorithm for position controlled robot arms in contact with surfaces of unknown linear compliance is reported. This adaptive hybrid controller is based on a previously reported the one-dimensional implicit adaptive force controller. The controller is shown to provide global asymptotic convergence of task-space force and position trajectory tracking errors to zero when the robot is under exact or asymptotically exact inner loop position control. An additional result which guarantees arbitrarily small force errors for bounded inner loop position and velocity tracking errors is presented. Comparative experiments show the new adaptive position based hybrid controller and its non-adaptive counterpart to provide performance superior to that of previously reported position based force controllers.