Position and Force Control of Bilateral Teleoperation Systems With Time-varying Delays Based on Force Estimation

A position and force tracking control based on force estimation is proposed for bilateral teleoperation systems with time-varying delays. A time-delay state observer is employed to estimate the system state variables affected by the delays. To estimate the interaction forces effectively, a force estimation algorithm with adaptive law is designed. Based on the estimated states and forces, a P+D controller is designed to simultaneously guarantee the position and force tracking of the system. The stability and tracking performance of the closed-loop system are proved via Lyapunov functions, and the feasibility of the proposed control is verified by both simulations and experiments. The proposed control can improve the position and force tracking performance of bilateral teleoperation systems under time-varying delays. Meanwhile, it neither requires force measurement nor the bound of the derivative of the time-varying delays to be within one.