Wave Variable Sliding Mode Control Design for Bilateral Tele-Operation Systems using Haptic Interfaces

Wave transformation is an attractive method for tele-operation systems subject to significant time delays. The proposed method can maintain passivity of the communication channel regardless of the amount of delay. However, this method can potentially introduce position-tracking errors. The position tracking performance can become seriously unsatisfactory when the delay is time varying. Sliding mode control is an effective robust technique that is particularly useful when one considers tracking control problems with presence of uncertainties and disturbances. The control objective is to force the system dynamics to approach a sliding surface and to remain on it for all future time in order to eliminate or minimize tracking errors. In this paper, a randomly time varying delay is considered in the tele-operation system. A sliding mode controller is designed to ensure a precise position tracking control of the slave side to the master´s command in a bilateral tele-operation system operating in a virtual environment using a haptic interface.