An enhanced wave-variable based four-channel bilateral teleoperation control design

Good transparency performance (including position tracking and force feedback) is an important issue for teleoperation control design. The four-channel control approach, which is based on the impedance matching, is effective to achieve the good transparency performance of teleoperation system. However, the shortcoming of this approach is the ignorance of time delay in the communication channel and thus deteriorating the system's stability. Some passivity based control approaches (e.g., wave variable transform) are developed to guarantee the system's stability under time delay, and have been tried to apply into four-channel control design, but the transparency performance may decrease since the traditional wave-variable may suffer some performance limitations (e.g., wave reflection). Thus, simultaneously realizing the stability and good transparency performance for four channel teleoperation system remains a challenging issue. In this paper, an enhanced wave-variable based four-channel control design is developed for bilateral teleoperation system to guarantee stability and further improve transparency performance. The time-delay compensator by the modified wave transform and the local force feedback are provided to compensate the distortion by reducing wave reflection. The simulation under time-varying delays is carried out, and the results show the obvious improvement of the proposed approach to achieve good transparency performance compared to the previous four-channel control designs.