Sliding-mode-based impedance controller for bilateral teleoperation under varying time-delay

Abstract

In the previous works, we have proposed new con tml schemes based on the sliding mode control and impedance control in order to cope with varying time delays. However, the previous controller needs local compliance to 1'ed'l 1ce contact for' ces between the slave and environment. In this paper, we modify the previ ous one to have a sliding surface for the slave include an impedance model. Since the nonlinear gain of the sliding controller is independent of the time delay as in the previous proposed controllers, it is not necessary to measure or estimate the time delay to implement the controller. The validity of the proposed contml scheme is demonstrated by experiments with a i-do] master/slave system connected through the Internet. IntroductionBilateral teleoperation systems transmit the in formation on the force at the slave to the master, which can considerahly improve their task perfor mance. However, these systems easily becomes un stable when communication time delays between the master and the slaVf� exist. Anderson and Spong [1] pointed out that even a small constant time delay could make bilateral �ystem� un�table and certainly degrade the operator's intuition and performance.Recently, more and more computer networks such as the Internet arc used as communication channels of teleoperation systems due to their availability and flexibility.With the computer networks, however, the communication time-delays between the master and the slave are not only significantly large but also changing depending on network congestions, which could make the overall system unstable.