USDE-based Synchronization Control for Bilateral Teleoperation System Subject to Time-Varying Delay

Time-varying delay, as one of the most prominent issues existing in teleoperation system, throws a critical threat on the teleoperation system stability. To address this issue, this paper proposes a novel synchronization control for nonlinear uncertain bilateral teleoperation systems in the presence of time-varying delay. Firstly, a filter error variable is designed to avoid using both local and remote acceleration signals. Then, a set of first-order low-pass filter operations are employed to construct an unknown system dynamics estimator (USDE) to handle the system uncertain dynamics, which revolves the Coriolis/gravity dynamics, external disturbances and remote velocity. With the suggested filtered error and USDE, a feedback controller is developed, which can not only improve the system synchronization but also has the capability of accommodating the influence of time-varying delay. Rigorously theoretical analysis is conducted by choosing the Lyapunov-Razumikhin candidate function to prove the stability of the closed-loop system. Finally, simulation results are provided to illustrate the effectiveness of the proposed method.