A Pragmatic Approach to Bi-Directional Impedance Reflection Telemanipulation Control: Design and User Study

Force feedback generally increases the effectiveness of execution and sense of embodiment on telemanipulation systems. However, systems with force feedback are vulnerable to time delays, reducing their transparency and stability. In this letter, we implement a bi-directional impedance reflection controller, a concept that was presented already in 1989 by Blake Hannaford Hannaford et al. 1989 but was never fully implemented. In this method, the simplified impedances of the operator and the environment are reflected back to the remote robot and haptic interface, respectively. A trajectory predictor is added to compensate for the delayed motion. We then evaluated the effectiveness of the system in a user study, comparing it to a system with a classical bilateral impedance controller with passivity layers. Three time delay groups (0, 10, and 20 ms one-way delay) of 10 participants each executed different tasks with both controllers. The results show that the bi-directional impedance reflection controller performs significantly better in the 10 ms and 20 ms time delay groups, in terms of task performance, user experience and sense of embodiment. We conclude that this study is the first to show that bi-directional impedance reflection can be effectively used with time delays of at least 20 ms.