Design and implementation of a modified communication disturbance observer for teleoperation systems

In this paper, a novel structure for a communication disturbance observer in teleoperation systems is proposed to achieve robust stability. A time delay compensation method based on the concept of network disturbance and a communication disturbance observer (CDOB) has been proposed in past research. Unlike model-based approaches, it works without a time delay model. Therefore, it can be implemented in teleoperation systems with unknown and time varying delay. However, it has been observed that the system model errors and external disturbances seriously affect the steady-state characteristics. Hence, in this paper, to achieve robustness against disturbance and model uncertainty, the structure of the conventional CDOB is modified and a new structure for the CDOB in teleoperation systems is proposed, which uses the slave's delayed torque instead of its delayed position for time delay compensation. The desired transient response characteristic is achieved by designing the controller parameters. The time delay in the communication channel has been simulated by PCs in past studies, but in this paper, by implementing the communication channel through the TCP/IP protocol in the experimental setup, the effectiveness of the proposed structure is studied in the presence of real time delay and compared with the Smith predictor, the conventional CDOB, and other structures of CDOBs.