It is readily apparent that a more dexterous and practical robot hand will be needed both in space and for commercial applications. However, although robots can succeed in many fields, highly advanced robotic hand have not been used. In our laboratory, robot hands that are useful for both in space and in commercial use are developed. The robot hand for space is designated as the REXJ Hand. It has been developed by remodeling another robot hand designed for ground use. The REXJ Hand will be launched to the International Space Station in 2011 as a part of the REXJ Project. Remodeling of a normal robot hand to a space robot hand is described herein.

Satellite capture in space is difficult in a dynamically changing environment. A vision sensor guiding a capturing manipulator toward a satellite can have difficulty recognizing a target covered with shining foil in rapidly changing lighting conditions. Satellite-capturing requires high reliability since space systems are costly. Therefore, it is necessary to be able to detect system limits, to abort a task, or to change a strategy In order to avoid catastrophic failure. Monitoring techniques in a layered-control architecture are proposed for conducting robotic satellite-capturing. The results of ground experiments are also presented.

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.

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 operator's input force are different, as in the surface-tracking task.

Space systems have become essential elements providing services of telecommunication, Earth observation and navigation to support our daily lives. With the expanding space activities, more and more space systems have become essential elements providing services of telecommunication, Earth observation and navigation to support our daily lives. With the expanding space activities, more and more satellites are being injected into wrong orbits for their missions and stranded due to failures of rockets. There is a potential need to rescue them by capturing and towing them to the appropriate orbits. Manipulator capture using visual servoing is one of the most promising ways to capture a stranded satellite that does not have a special mechanical interface or a visual marker on it. A study is now being conducted to design a manipulator-based capturing system, taking into account the special aspects of space such as lighting and available computing power. The first results of an experimental study are presented with an explanation of the experimental system in this paper.

To realize practical orbital servicing missions in the 21/sup st/ century, we have developed a new system concept for an orbital servicing vehicle named Hyper-OSV (Orbital Servicing Vehicle), which has higher speed manipulation capability and larger operation area than OSVs that were proposed in the 1990's. The main feature of Hyper-OSV (HOSV) is the separation of the operation function and the long-term in-orbit surviving functions such as a solar panel and a large communication antenna. This releases HOSV from attitude restrictions and flexible dynamics and provides a large operation area. The second feature of HOSV is the reconfigurable function that allows HOSV to perform various orbital servicing missions. One of the most difficult missions of HOSV is the noncooperative satellite capture. Separation of the operation function and the long-term in-orbit survival functions gives HOSV an agile working ability. Thus, we have proposed a satellite capturing strategy using an agile orbital servicing vehicle like HOSV and have been conducting its feasibility study. This paper outlines Hyper-OSV first, and then presents the satellite capturing strategy using an agile orbital servicing vehicle and feasibility studies of the satellite capturing.

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.

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 Shuttle's 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.

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.

On-orbit service such as refuelling, repairing and re-orbiting is highly required for space activities. For on-orbit service, it is one of the most important and most difficult technique to capture a "customer satellite" by a robot arm which can move dynamically in a wide range of space. An on-board autonomy "machine vision" is highly required to perform this dynamic task, since a control loop including the ground station tends to be unstable due to the communication time delay between a ground station and a space robot. An experiment was conducted using the Japanese Engineering Test Satellite VII (ETS-VII) to capture a free floating satellite on orbit first time in the world. Successful results of the experiment are presented.

The National Space Development Agency of Japan (NASDA) launched the ETS-VII (Engineering Test Satellite No.7) on November 28, 1997 to conduct rendezvous docking and space robot technology experiments. ETS-VII is the world's first satellite that used a robot arm on a satellite. The robot arm was 2 m long and was tele-operated from the on-ground control station. The mission of ETS-VII lasted for two years and brought may experiences and results. The paper summarizes experiences and results of the ETS-VII robot satellite.

The space robot is the indispensable tool for future space activities such as building and operation of the international space station, inspection and repair of orbiting satellites, and conducting lunar/planetary explorations. National Space Development Agency of Japan (NASDA) developed and launched an engineering test satellite named ETS-VII (Engineering Test Satellite 7) on November 28, 1997 to conduct the space robot technology experiments. This paper shows preliminary results of the ETS-VII space robot experiment mission.

NASDA is to launch an engineering test satellite, named ETS-VII (Engineering Test Satellite VII), to conduct rendezvous docking and space robot technologies experiments in an Earth orbit in the year 1997. ETS-VII satellite carries a 2-m long robot arm which has 6 degrees-of-freedom. The robot arm will be teleoperated from a ground control station using a data relay satellite in the geostational Earth orbit. The communication capacity of the link is limited and there is a time delay of about 4 to 6 seconds. This paper introduces how the teleoperation system of the ETS-VII robot experiment system is designed.

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.

When a robot arm is mounted on a satellite to perform tasks, satellite attitude must be stabilized to keep communication link and to generate electrical power from its solar panels. Most past studies about free-flying space robots assume that the satellite platform is uncontrolled. Since performance of the space qualified onboard computer is not enough to handle the complicated control system, coordinated control of the robot manipulator control system and the satellite attitude control system is proposed in this paper. The robot control system estimates the angular momentum which the robot arm will produce. The satellite attitude control system compensates the robot arm's reaction by the feed forward momentum control. The robot control system also controls robot arm motion not to generate excess reaction against the satellite platform.

National Space Development Agency of Japan (NASDA) is to launch an engineering test satellite named ETS-VII in the year 1997 to develop and perform in-orbit test of rendezvous docking and Space robot technologies. ETS-VII's robot experiment includes (a) performance evaluation of satellite mounted robot system, (b) coordinated control of satellite attitude and robot arm, (c) teleoperation of the satellite mounted robot arm, (d) demonstration of in-orbit satellite serving. The ETS-VII satellite carries a robot arm of 2 m long and 6 dof which will be teleoperated from a ground control station. This paper shows mission, design and development status of ETS-VII space robot experiment mission.

There are many tasks to be performed by space robots. However a single end-effector can not meet the individual task's requirements. NASDA is to launch an experimental robot satellite named ETS-VII. The satellite has a 6-DOF robot-arm to handle many experimental payloads. Payloads vary in mass, shape and size. Interfaces between payloads and the end-effector are standardized using grapple fixtures. Additional tools with grapple fixtures are also developed to meet specific task requirements. This paper shows current status of the space-robot's EVA end-effector and development result of the ETS-VII's end-effector, grapple fixtures and tools.

ETS-7 is the 7th engineering test satellite of NASDA (National Space Development Agency of Japan) to be launched in 1997. The satellite has a 6-DOF robot arm for space robot technology experiments. Mass of the payload varies from a few kg to 400 kg and mass of the satellite is about 2.2t. Therefore a dynamic interaction between the robot arm motion and the satellite attitude motion is not negligible for satellite attitude stability and robot arm motion planning. Attitude of the satellite must be stabilized since a communication link with a ground control station is established by a dish antenna directed to a data relay satellite in the geostationary orbit. Two wing shaped solar panels must also be pointed to the Sun. It is difficult to control the satellite attitude and a robot arm in a combined mode since the current spaceborne computer does not have enough computational power to handle the complicated dynamics in real time. This paper proposes a distributed and cooperative control method which connects the robot control system and the satellite attitude control system. The robot control system controls the robot arm and estimates the reaction force to the satellite. The attitude control system will compensate this reaction force by the feedforward control. The robot control system will also check its motion plan not to produce large attitude error. This distributed and cooperative control method avoids excess onboard computational power and complicated interface between the two control systems. This method is applicable for both reaction (momentum) wheel control and gas jet thruster control.>

A layered architecture was proposed for the command and control system of semi-autonomous space robots, and the proposal was validated by the demonstration of replacing an orbital replacement unit on a testbed for space robots. The command and control system consists of four layers: a task scheduling module, a macro-task module, a micro-task module, and an intelligent control module. The macro- and micro-task modules were implemented on top of Lisp and have a symbolic world model which is integrated with an online robot simulator developed upon a commercial robot simulator for industrial robots. The task decomposition and expansion from macro commands to micro commands was carried out dynamically by consulting the world model, and the impending collision between a manipulator and obstacles was detected by the online robot simulator. A small visual marker which can measure 6-DOF was designed, and a visual feedback system was developed with the visual marker.