Adaptive Design of Bilateral Control Systems for Multivariate Reference Models

A bilateral control system aims to share force and position information bidirectionally between similar manipulators. The manipulator has unknown nonlinear plant perturbations caused by friction in joints. This makes it difficult for the bilateral control system to achieve stability and good transparency performance. In this paper, an adaptive control system is developed for single-axis DD-motor which is used as the joints of the manipulator to handle the aforementioned issue. The adaptive control makes the DD-motor linear time-invariant by conforming an output of the DD-motor to an output of the reference model. In addition, the bilateral position and force controllers are designed for the reference models. If the outputs of DD-motor converge to the outputs of the reference model, stability of the proposed control system is guaranteed by passivity. Some simulation results show that the proposed control system performs great transparency of both position and force tracking when the plants have time-varying nonlinear friction.