Networked dual-user teleoperation with time-varying authority adjustment: A wave variable approach

This paper introduces the concept of authority adjustment in a dual-user system and presents a wave-variable-based controller to guarantee dual-user system stability in the presence of a time-varying dominance-factor and a constant communication delay. A time-varying dominance factor is useful in a dual-user system as it provides greater convenience and practicality in telerobotics-based applications such as surgical training. However, despite the importance of this issue, it has not received much attention in the literature on dual-user systems. The controller proposed in this paper includes a local impedance-based controller adopted from the literature for each robot and a wave transformation modified for the dualuser system with a time-varying dominance-factor. In order to investigate closed-loop stability, passivity theory has been applied and it has been shown that the proposed wave-variable-based controller guarantees system stability in the presence of a time-varying dominance factor, while the communication channels have constant time delays. Validity of the controller has been demonstrated via experiments.