State Reconstruction of Remote Robotic System Using Delayed Output and Torque Estimation

Abstract

The state reconstruction problem for a remote robotic system with communication delay is investigated in this paper. A symmetric estimation scheme is proposed based on both input and output observers. First, a sliding-mode disturbance observer is designed to estimate the input torque of the robot on the remote side. Then, by using the received output and torque estimation subject to time delay, a novel predictive observer is proposed on the local side to reconstruct the real-time joint angles and velocities. Based on a Lyapunov approach, sufficient conditions are obtained to make sure that the estimation errors can converge exponentially to bounded regions through selecting proper observer gains. Simulation studies are conducted to verify the effectiveness of the proposed strategy. The estimation error of state reconstruction is decreased by 14% in terms of the integral square error when compared to the standard high-gain predictor, and the simulation results demonstrate the effectiveness of force estimation under disturbances and model uncertainties.