The application of discrete-time adaptive impedance control to rehabilitation robot manipulators

Rehabilitation robot manipulators for persons with disabilities often encounter contact tasks in uncertain environments. In order for rehabilitation robots to readily adapt to their changing environment, an advanced and practically implementable control approach is needed. This paper present a robot manipulator control scheme which combines a discrete-time adaptive controller with a discrete-time impedance dynamics trajectory generator. The discrete-time adaptive controller assures the trajectory tracking of robot manipulators while the discrete-time impedance dynamics trajectory generator regulates the relation between forces and motions. By using the adaptive controller the knowledge of either the structure or the parameter values of the robot dynamics is not required. The proposed discrete-time adaptive impedance control scheme is simple and suitable for the digital computer based real-time robot manipulator control. Simulations are given for a planar two-link manipulator arm under discrete adaptive impedance control with forces contaminated by Gaussian distributed noise. Results are presented to demonstrate the proposed scheme