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.

No abstract

No abstract

No abstract

Abstract:To conduct tasks that need high dexterity by teleoperation, a unified hand/arm master-slave system was developed. To measure the dexterity of individual teleoperation systems all over the world in equal condition, we propose toy block assembling (LEGO TM ) as the benchmark test for teleoperation systems. Meanwhile, a bilateral teleoperation experiment with ETS-VII (Engineering Test Satellite No.7) was conducted on November 22, 1999. Round-trip time for communication between the NASDA ground station and ETS-VII was approximately six seconds. These two results are the first step to improve the dexterity of teleoperation systems and to investigate the relationship between time delay and dexterity.

In a force-reflecting bilateral teleoperator with a time delay, teleoperator stability is a serious problem. We have studied a bilateral teleoperator system with a time delay. We obtained stable conditions using proportional derivative-based (PD-based) control law. In this paper, PD-based control law is further studied. First, we study a PD control law with relative damping gain and its stabilizing effect that previously has not been studied quantitatively. A stable condition is derived with this PD-based controller with relative damping gain. Next, teleoperator performance by the PD control law with relative damping is evaluated and compared to PD control laws with only grounded damping using transparency analysis with a hybrid matrix. We showed that, the performance of the PD-based controller can be improved by introducing relative damping gain into the controller. As a controller design example, numerical simulations and 1-DOF experiments were conducted. Finally, peg-in-hole experiments and performance evaluations in realistic multi-DOF environments were conducted to demonstrate performance improvements by introducing the relative damping. A controller design that guarantees both stability and performance was achieved by iterating stable gain setting and performance evaluation.

No abstract

SUMMARYStability is a major problem with bilateral teleoperator when there is a transmission time delay. By adding adequate damping gain into position servo, a stable bilateral control can be achieved under the existence of time delay. However, large damping gain is required to stabilize the system and the performance is degraded. In this paper, the performance improvement by introducing a high-pass filter into a proportional derivative-based teleoperator with time delay has been studied. We proposed new control law and derived the stability condition. We demonstrated the performance improvement using a hybrid matrix, 1-degree of freedom (DOF), 2-DOF simulations, and 2-DOF peg-in-hole experiments.