IEEE International Workshop on Intelligent Robots and Systems
IROS ’90

TELE-EXISTENCE MASTER SLAVE SYSTEMFOR RE�TE MANIPULATIONSUSUMU TACHI, HIROHI KO AR"I, AND TARO MAEDAMEc•悦NICAL E 附INEERI 陥 LABαlATORY, MITITSUKUBA SCIE舵E CITY, IBARAKI 305 JAPANABSTRACT: A tele-existence masterslave system for remote manipulation
experiments is designed and developed,
and an evaluation experiment of atele-existence master slave system isconducted. By making a comparison of A
tele 『 existence master slave systemwith a conventional master-slave sys­tem, efficacy of the tele-existencemaster slave system is verified andthe superiority of the tele-exis.tence
method is demonstrated quantitatively.
INTRODl応TION
Tele-existence aims at a natural andefficient remote control of robots byproviding the operator with a realtime sensation of presence. It is anadvanced type of teleoperation system
which enables a human operator at thecontrols to perform remote manipula­tion tasks dexterously with the feel­ing that he or she exists in one of
the remote anthropomorphic robots in
the remote environment, e. g. , in a
hostile environment such as those ofnuclear radiation, high temperature,and deep space. Much ef.:fort has been
made for the development of tele­
existence [ J -5] or tel epresence [6-8)through the feedback of rich sensory
information which the remote robot has

acquired to provide the operator witha real-time sensation of presence.
In the previous reports [I, 21. theprinciple of the tele-existence sen.sory display was proposed. Its design
procedure was explicitly defined.
Experimental visual display hardware
was buil 七 and the feasibi Iity of thevisual display with the sensation ofpresence was demonstrated by psycho­
physical experiments using the test
hardware. A met hod was al so proposed
to de velop a mobile t el e-existencesystem, which can be remotely driven
with the auditory and visual sensationof presence. A prototype mobile tele­vehicle system was �onstructed and thefeasibility of the method was evaluat­
ed (2). The principle of active power
assistance was applied for controllingthe visual display with two degrees of
freedom [3, 4). In order to study theuse of the tele-existence system in
the artificially constructed environ­ment, the visual tele-existence simu­
lator was designed, a quasi-real-timebinocular solid model robot simulator
was made, and its feasibility wasexperimentally evaluated [5-].
In this paper, a tele-existence masterslave system for remote manipulation
experiments is designed and developed,-343-

servo loop is used in this experiment.
The actual servo system is shown inFig. 2. The computer generates a pu 1 sesequence to assign the desired posi 『tion, and the position
control isconducted by counting the difference
between the computer genera吐ed pulseand the measured pulse from an en­coder. Angular velocity is estimatedby using a frequency-vo 1 tage con­verter. Feedforward compensation isconducted by a compensation filter asshown in Fig. 2.

visual display with a sensation ofpresence. The audio visual display iscarried by a link mechanism with six
degrees of freedom. The link mechanism
force
cancelsallgravitational
through a counter balancing mechanismwith a relatively wide range of opera­tion (up/down: -500 ""400 mm; right/l主ft： ー 300 Aノ 300 mm; forward/ back­ward: -300800 mm). It also enables
the display to follow the operator shead movement
precisely enough toensure his/her ordinary head movement.
Maximum measured
inertial force iswithin 5 kgf. The master arm consistsof ten degrees of freedom. Seven
degrees of freedom are allocated forthe arm itself, and an additional
three are used to comply with the bodymovement.

～Fig. 2 Block diagram of the control system.
The vision system of the slaνe robot
consists of two color CCD video headsof the TV cameras. Each CCD has
420,000 pixcells and has its opticalsystem with a focal length of f=15 mm
and an aperture of F 1. 6. Focus isautomatically controlled by the TTL AF
method. The separation of two cameras
are set at the distance of 65 mm. andthe two cameras are aligned parallel.
As for the auditory system, two micro­
phones are placed 243 mm apart fromeach other, and the same locational「 elationis used for the auditory
display of the master system.
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Fig.3 General view of the tele-existence mastersystem.

ごigure 3 shows a general view of thetele-existence master’ system and Fig.
4 shows the schematic diagram of the噌 chanism of the system developed.
A「 uman operator wears a stereo audio

Figure 5 shows the principle of thegravitational cancellation mechanism.
In the parallel link mechanism ofFig. 5, balance weights m2 and m3 andlever lengths d1, d2’ d3 and d4 are-345-