Bilateral Adaptive Control of Nonlinear Teleoperation Systems With Uncertain Dynamics and Dead-Zone

Dead-zone is one of the most common hard nonlinearities ubiquitous in master–slave teleoperation systems, particularly in the slave robot joints. However, adaptive control techniques applied in teleoperation systems usually deal with dynamic uncertainty but ignore the presence of dead-zone. Dead-zone has the potential to remarkably deteriorate the transparency of a teleoperation system in the sense of position and force tracking performance or even destabilizing the system if not compensated for in the control scheme. In this paper, an adaptive bilateral control scheme is proposed for nonlinear teleoperation systems in the presence of both uncertain dynamics and dead-zone. An adaptive controller is designed for the master robot with dynamic uncertainties and the other is developed for the slave robot with both dynamic uncertainties and unknown dead-zone. The two controllers are incorporated into the four-channel bilateral teleoperation control framework to achieve transparency. The transparency and stability of the closed-loop teleoperation system is studied via a Lyapunov function analysis. Comparisons with the conventional adaptive control which merely deal with dynamic uncertainties in the simulations demonstrate the validity of the proposed approach.