Composite nonlinear bilateral control for teleoperation systems with external disturbances

This paper presents a new composite nonlinear bilateral control method based on the nonlinear disturbance observer ( NDOB ) for teleoperation systems with external disturbances. By introducing the estimations of NDOB and systemsʼ nominal nonlinear dynamics into controller design, a NDOB based composite nonlinear bilateral controller is constructed to attenuate the influence of disturbance and uncertain nonlinearities. As compared with the existing bilateral control methods which usually achieve force haptic ( i.e., contact force tracking ) through a passive way, the newly proposed method has two major merits: asymptotical convergence of both position and force tracking errors is guaranteed; disturbance influence on force tracking error dynamics is rejected through the direct feedforward compensation of disturbance estimation. Simulations on a nonlinear teleoperation system are carried out and the results validate the effectiveness of the proposed controller.