Impedance Control Of Nonlinear Multi-DOF Teleoperation Systems With Time Delay Absolute Stability

A nonlinear robust adaptive bilateral impedance controller is proposed to provide the absolute stability of multi-DOF teleoperation systems with communication delays, in addition to the force and position tracking performance. The proposed controller realizes two desired (or reference) impedance models for the master and slave robots using a new nonlinear robust version of the Model Reference Adaptive Control (MRAC) scheme. Using the absolute stability criterion, the robustness condition of the teleoperation system against communication delays is obtained, resulting in suitable adjustments of parameter values in the desired impedance models. In addition, using the Lyapunov stability theorem, the tracking performance of the master and slave robots and the robustness of the proposed controller against parametric and bounded unstructured modeling (non-parametric) uncertainties are proven. The performance of the proposed nonlinear bilateral controller is investigated by performing some experiments on nonlinear multi-DOF telerobots with and without communication delays.