Adaptive control of nonlinear teleoperation systems with varying asymmetric time delays

In this paper, a new adaptive control design method for nonlinear telerobotic systems with varying asymmetric time delays is presented. Using the proposed controller, it is possible to synchronize the state behavior of the local and the remote robots. While prior art on adaptive teleoperation has addressed stability in such systems only for constant delays, we guarantee asymptotic stability in the presence of delays that may be time-varying and/or unequal in the forward and backward directions. Using the proposed controller, asymptotic stability of the bilateral teleoperation system subject to any bounded varying delay with a bounded rate of variation can be guaranteed. The proposed controller also has the ability to cope with parameter variations in the dynamics of the local and the remote robots. To study the transparency of the closed-loop teleoperation system, we prove that the position and velocity errors between the local and the remote manipulators converge to zero asymptotically. To show the efficiency of the proposed controller, simulation results on a pair of two-degree-of-freedom manipulators with varying time delays in the communication channel are presented.