Influence of time-varying communication delay in adaptive controller based bilateral control system

Communication delay between a master robot and a slave robot destabilizes a bilateral control system. And some recent researches show that an adaptive controller that dynamically determines the master's controller gain depending on a stiffness of a contact object is effective to improve stability. However few researches show an influence of time-varying communication delay in adaptive controller based bilateral control systems. This paper therefore verifies an influence of time-varying communication delay. A PI (polynomial interpolation) with a schmitt trigger is utilized to estimate a stiffness of a contact object. Simulation results show that the PI based estimation method has a robustness against a constant/time-varying communication delay. An experiment of a bilateral control over an IP (Internet Protocol) network emulator also show the validity of the estimation method.