Toshitsugu Doi

Ground-space bilateral teleoperation of ETS-VII robot arm by direct bilateral coupling under 7-s time delay condition

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.

Model-based space robot teleoperation of ETS-VII manipulator

In our previous research, we developed space robot teleoperation technology to achieve control from the ground of effective manual manipulations in orbit. To solve the communication time delay in the space robot teleoperation, we propose a mixed force and motion command-based space robot teleoperation system that is a model-based teleoperation. Moreover, we have also developed a compact 6-degree-of-freedom haptic interface as a master device. The important features of our teleoperation system are its robustness against modeling errors and its ability to realize the force exerted by the operator at the remote site. We introduce a new control method, which modified our model-based teleoperation system, to control the real robotic system Engineering Test Satellite VII manipulator. Surface-tracking and peg-in-hole tasks have been performed to confirm the effectiveness of our system. The experimental results obtained with our system including the haptic interface demonstrate its ability to perform these tasks in space without any major problems. We also evaluated different master device approaches for the model-based space teleoperation system. For this purpose, we used two methods, which are a master-slave (MS) approach and a force-joystick approach. Our results show that the MS approach is the best control method for contact tasks in which the directions of motion of the slave arm and of the operators input force are different, as in the surface-tracking task.

Ground-space bilateral teleoperation experiment using ETS-VII robot arm with direct kinesthetic coupling

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.

Tele-manipulation of a satellite mounted robot by an on-ground astronaut

An experiment to teleoperate a robot arm on a satellite from an onground control station was conducted by an astronaut who has extensive on-orbit experience in operating the Space Shuttles robotic arm. This experiment aimed to evaluate/compare a teleoperation system, which we developed, with the teleoperation system of the Space Shuttle Remote Manipulator System (SRMS). There was a time delay of about 6 seconds in the teleoperation control loop of the satellite-mounted robot. However, the teleoperation experiments were satisfactory conducted with helps of various operator assistance functions.

Model-based teleoperation of a Space robot on ETS-VII using a haptic interface

In our previous works, we have proposed a mixed force and motion commands-based space robot teleoperation system and a compact 6-DOF haptic interface to achieve an effective manual teleoperation. Until now, the effectiveness of this system and the haptic interface has been confirmed by the experiments in our laboratory. The most important features of this teleoperation system are robustness against modeling errors and ability to realize the operator exerted force at a remote site. In this paper, elements of this system and the haptic interface have been employed to teleoperate the 6-DOF manipulator mounted on the Engineering Test Satellite VII (ETS-VII) which is a real space robotic system. Surface-tracking and peg-in-hole tasks with modeling errors have been executed in this experiment. The results show that our space robot teleoperation system including the haptic interface has been able to execute these tasks in real space environment without any big problems.

Teleoperation system of ETS-VII robot experiment satellite

Tasks to be performed in space will increase in near future such as assembly of the space station, exploration of lunar and Mars surface, repair of failed satellites in orbit. Space robots which can be teleoperated from a ground control station are desired to conduct these tasks. National Space Development Agency of Japan (NASDA) is to launch an engineering test satellite named ETS-VII to conduct rendezvous docking and space robot technologies experiments for the above future missions. ETS-VII satellite has 6-DOF robot arm of about 2 m long which will be teleoperated from an on-ground control station in Japan. This paper describes the teleoperation system of the ETS-VII robot arm.

Bilateral Teleoperation: Towards Fine Manipulation with Large Time Delay

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™) 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.