Time delay compensation by communication disturbance observer in bilateral teleoperation systems

In a research area of bilateral teleoperation systems, time delay generated in communication line is one of very serious problems. Time delay in control systems induces severe phase delay. Then the phase delay possibly destabilizes the system and deteriorates performance of the system. Therefore many studies about time delay in bilateral teleoperation systems have been conducted so far. Some researches have accomplished stabilization method or compensation method of constant time delay. However compensation of time-varying or fluctuant time delay has not been completed. This paper introduces a novel compensation method of time delay. The method is based on the concept of network disturbance (ND) and communication disturbance observer (CDOB). CDOB estimates ND and estimated value is utilized for the compensation of time delay. In addition, because it does not need delay time model, it can be applied to systems with time-varying or fluctuant time delay. Furthermore the method is very simple and it is very easy to implement. The effectiveness of the proposed method is verified by simulation and experimental results.