Time delay compensation for tendon-driven bilateral control using modal decomposition and communication disturbance observer

Abstract

Master-slave robots with transmission of force sensation have gotten a lot of attention. 4ch-bilateral control realizes the transmission. Realizing lightweight multi-DOF robots for the system and compensating adverse effects based on communication delay are challenges for the system. For realizing lightweight multi-DOF robots, tendon-driven mechanisms are suitable as driven systems and driving systems can be separated. In order to compensate the adverse effects from communication delay, communication disturbance observer (CDOB) can be applied. CDOB requires slave system model. As it is difficult to make a model of force acting on slave system is difficult, CDOB is not appropriate for force control. However, tension control is based on force control. Therefore, in this paper, a time delay compensation method for bilateral control system with tendon-driven mechanisms is proposed. In this method, tension control and CDOB are constructed in different mode, which are independent of each other. The experimental results of the proposed method show the validity. Strings were strained with desired force by the tension control, and the adverse effects of communication disturbance was compensated by CDOB.