Shigeru Tsuchiya

A fault-tolerant control algorithm having a decentralized autonomous architecture for space hyper-redundant manipulators

Adaptation to partial failure is one of the most important requirements for space robotics, since space robots cannot be repaired after they have been launched. We propose a decentralized autonomous control algorithm for hyper-redundant manipulators that uses parallel processing with low-performance processors to achieve this adaptation. In this paper, a number of manipulator joints are locked at a certain angle in a computer simulation and the adaptability of the control algorithm to these failures is assessed. The control algorithm successfully continues its positioning task at a rate of more than 90%, even after half of its joints have failed. The control algorithm is also compared with behavior-based control architecture.

Mechanism for assembling antenna in space

The development of large and precise space antennas is one of the most important topics in constructing space infrastructures. We evaluated an approach to assembling large and accurate space antennas which uses space robots. The assembly mechanism was launched together with the ETS-VII, the first telerobotic satellite from Japan, and its performance, including fully automatic assembling, was verified. The assembling-type antenna and the results of antenna assembly experiments are discussed.

Audio feedback system for teleoperation experiments on engineering test satellite VII system design and assessment using eye mark recorder for capturing task

When operating space robots, safety and reliability are the most important issues-even at the expense of dexterity and swiftness. This makes it very stressful for operators to teleoperate space robots, especially since they cannot be repaired during operation, unlike ground robots. Furthermore, operators have to quickly analyze a large amount of information about the target objects and immediately make decisions on how to proceed. The majority of this information is presented visually, including digital values, status displays, 3D computer simulation, and camera images. Therefore, we developed an audio feedback system that can convey some of this information in order to improve the operators decision-making and avoid accidents. We used an eye-mark-recorder to assess the performance of this system. Audio systems for information presentation have previously only been proposed for ground-based operation systems. This is the first case in which sound has been utilized for space robot operation, even though sound does not actually exist in space.

A module type manipulator for remote inspection in space

The major issue now in space robot development is cost reduction. The modular type re-configurable robot is one unique solution for such a reduction in costs. If the manipulator is controlled by cooperating multiprocessors in a decentralized manner, the robot can overcome partial failure. In this type of system, when a module fails, the manipulator can eliminate the faults by reconfiguring itself. We introduce a re-configurable modular-type manipulator for space utilization. The manipulator system is interconnected by a joint mechanism which can be connected and disconnected by simple robotic motion and also resist inertia during space operation. The modules are also specially designed for thermal, vacuum, and radiation conditions. We have adopted a decentralized control algorithm for the redundant manipulator, which automatically adapts to the manipulator reconfigurations.

Audio feedback system for engineering test satellite VII

An efficient and reliable interface to manage telemetry information is most important in the teleoperation of space robots. Operators need to be able to recognize and verify large amounts of telemetry information quickly and accurately. Visual information around the workspace of space robots is very limited, and the detailed position of work is uncertain. These difficulties raise the load on operators. We have been running experiments on assembling antennas using the Engineering Test Satellite VII (ETS-VII), so we are very much aware of the need for an effective man-machine interface to handle telemetry information. We have developed an audio interface system for the efficient operation of ETS-VII. Unlike a visual interface, this audio interface allows an operator to (1) perceive information even if pay small attention for it, and (2) easily identify trends and changes. The system analyzes telemetry information in real- time, and converts changes in the status of information into voice data, and changes in the magnitude of forces into the frequency of motor noise. The effectiveness of this audio interface was verified in operations of ETS-VII by monitoring eye movements over time. Time is measured by the mean interval between status changes and command submissions. An eye mark recorder records eye movements. The data suggests significant effects of the audio interface system.

Difference in the effects of an audio feedback system for difference in operation task and skill level of human operators in experiments of ETS-VII

We used an Audio Feedback System (AFS) to present some telemetric data to human operators, as auditory information in robot arm experiments with Engineering Test Satellite VII (ETS-VII). Our intention was to provide information that assists in easier and safer operation. We think that the human-machine interface presented to human operators should correspond to different tasks and to different skill levels of human operators. Fortunately, we had opportunity to assess AFS for two tasks those of a Commander and Monitor. The Commander operates the robot arm by transmitting tele- operation commands, while the Monitor checks the indications of telemetric data on a status display. During the experiment, the Commander and Monitor used a status display to check information on the robot arm. In the experiments, seven human operators, four Commanders and three Monitors, performed their respective tasks. In order to assess the effectiveness of AFS for various skill levels of human operators, an astronaut who has a very high level of skill in controlling the robot arm was included among the Monitors. In determining the effectiveness of AFS, we focuses on the eye movements of human operators. We thus used an eye mark recorder (EMR) to measure eye movements. When auditory information was given, average fixation times required to confirm telemetric data indicated on the status display were shortened except in the case of the astronaut. AFS had no effect on the astronauts performance.

Comparison between the astronaut and standard operators as telemetry monitor for effects of audio feedback system in the operation of the Engineering Test Satellite VII

It is the most important that we perform safe and reliable teleoperation of space robots in the experiment/operation using real satellite. Therefore we have developed and used Audio Feedback System (AFS) that use some auditory information such as motorized sound and prerecorded voice converted from a part of telemetry information to reduce loads to operators of space robots of the Engineering Test Satellite VII(ETS-VII). We applied AFS to the experiment ofAntenna Assembling Mechanism (AAM) which is experiment module of the Communications Research Laboratory (CRL) on the ETS-Vil for testing the mechanism of assembling structures in space. Our purpose of this study is to assess effectiveness of AFS by using the Eye Mark Recorder (EMR) which records eye movements for the astronaut and two operators as telemetry monitor who observe telemetry data. In results of macro shape of 0-500 (deg/sec) velocity distribution graph, average fixation time, and average velocity of eye movement, we have got important points as followings: ( 1) the spectrum patterns of velocity of eye movement of specialist operator of controlling space robots like an astronaut are significantly differed from other two operators, (2) the spectrum patterns of velocity of eye movement of specialist operator and nonexpert operator are not affected ofAFS, (3) the spectrum patterns of velocity of eye movement of well-trained expert operator was similar to specialist operator with AFS and similar to nonexpert operators without AFS, (4) average fixation time of specialist operator was not effected by AFS, average fixation time of well-trained expert operator, nonexpert operator became long without AFS support.

Decentralized kinematics algorithm for modular space robots

The Communications Research Laboratory has been studying the inspection technology needed for the first step of an Orbital Maintenance System (OMS) for maintaining space systems by inspecting satellites, re-orbiting useless satellites, and simply repairing satellites in orbit. OMS will use a modular manipulator for remote inspection. One of the most important issues concerning control of the modular manipulator is a determination process that utilizes its decentralized control architecture. In this paper, we introduce a decentralized kinematics control algorithm that automatically adapts to partial faults and reconfigures itself.

Evaluation of audio feedback system for Engineering Test Satellite VII

We have developed an audio interface system for the efficient operation of ETS-VII. Unlike a visual interface, this audio interface allows the operator: to observe information even if he is not focusing on it, and to easily identify trends and changes. The system analyzes telemetry information in real-time, and converts changes in the status of information into voice data, and changes in the magnitude of forces into motor noise frequency. The effectiveness of this audio interface was verified in ETS-VII operations by monitoring eye movements over time. Time is measured by the mean interval between status changes and command sub-missions. An eye-mark recorder records eye movements. With the audio interface, the operator has sojourned time to see graphic simulator/down link images. Without audio interface, the operator have sojourned to see telemetry display. Our data suggests that when using the audio interface the operator spends much less time looking at the display.