A bilateral teleoperation experiment with Engineering Test Satellite 7 (ETS-VII) was conducted on November 22, 1999. Round-trip time for communication between the National Space Development Agency of Japan ground station and the ETS-VII was approximately seven seconds. We constructed a bilateral teleoperator that is stable, even under such a long time delay. Several experiments, such as slope-tracing task and peg-in-hole task, were carried out. Task performance was compared between the bilateral mode and the unilateral mode with force telemetry data visually displayed on a screen. All tasks were possible by bilateral control without any visual information. Experimental results showed that kinesthetic force feedback to the operator is helpful even under such a long time delay, and improves the performance of the task.

A bilateral teleoperation experiment with ETS-VII was conducted on November 22, 1999. Round-trip time for communication between the NASDA ground station and ETS-VII was approximately six seconds. We constructed a bilateral teleoperator that is stable even under such a long time delay. Several experiments, such as slope tracing task and peg-in-hole task, were carried out. Experimental results showed that kinesthetic force feedback to the operator is helpful even under such long time delay and improves the performance of the task.

In previous work, we (1999) have proposed a control scheme based on wave variables. Unlike other methods, the proposed method could minimize the performance degradation due to the fluctuation of time delay. With this method however the system may potentially generate infinite energy in some special situations and the system stability could not be ensured rigorously. In this paper, we modify the method by introducing an energy input/output balance monitoring mechanism, which limits the energy that the system can generate. We conducted some simulation studies with a one DOF system. Simulation results show the validity of the proposed scheme.

Several approaches based on wave variables have already been proposed for bilateral teleoperation control under time-varying delay. However, these approaches are too conservative for keeping the system passivity or for estimating the amount of virtually constant time delay. These conservative approaches result in too much degradation of maneuverability from the constant time delay situations. We propose a novel control scheme that is also based on wave variables, but minimizes the performance degradation due to the fluctuation of the communication time delay. The proposed method is simple and easy to implement. We conducted some simulation studies with a one DOF system. Simulation results show the validity of the proposed scheme.