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CONTROL THROUGH STATE CONVERGENCE OF
TELEOPERATION SYSTEMS WITH VARYING TIME DELAY
Jos
´
e M. Azor
´
ın, Oscar Reinoso, Jos
´
e M. Sabater
Dpto. de Ingenier
´
ıa de Sistemas Industriales, Universidad Miguel Hern
´
andez
Avenida de la Universidad s/n, Elche (Alicante), 03202 Spain
Rafael Aracil
DISAM, ETSII, Universidad Polit
´
ecnica de Madrid
C/Jos
´
e Guti
´
errez Abascal 2, Madrid, 28006 Spain
Keywords:
Teleoperation, control system, time delay, state space.
Abstract:
Teleoperation systems that use Internet as communication channel must deal with varying time delays. In
these situations, the system can become unstable due to the irregular variations of the time delay. In this
paper, a control method of teleoperation systems that we presented considering constant time delays is applied
to control a teleoperation system with varying time delays. The control gains obtained with a constant time
delay can be used to control the teleoperation system with varying time delays because of the control method
robustness. Experimental results are presented to illustrate the validity of the method.
1 INTRODUCTION
In a teleoperation system, the human operator con-
trols the master manipulator to achieve that the slave
manipulator performs a remote task. In a bilateral sys-
tem, to improve the task performance, the interaction
force of the slave with the environment is reflected to
the operator. The existence of time delays in the infor-
mation transmission between the local and remote en-
vironment can destabilize bilateral teleoperation sys-
tems.
In traditional teleoperation systems, private trans-
mission media are used to perform the master – slave
communication. In these cases, a constant time delay
is assumable. Different teleoperation control systems
can be found in the literature to overcome the constant
time delay problem (Arcara and Melchiorri, 2002).
The evolution of computer networks, as Internet,
has powered to consider this media as communica-
tion channel in teleoperation systems. However, in
this media the communication time delay is not con-
stant, but it varies depending of the network traffic.
It is possible that bilateral control systems designed
considering a constant time delay would be destabi-
lized when varying time delays appear (Kosuge et al.,
1996). Several control systems have been proposed
in teleoperation with varying time delay: (Kosuge
et al., 1996), (Oboe and Fiorini, 1997), (Chopra et al.,
2003), etc.
In (Azor
´
ın et al., 2003a) we have proposed a new
design and control method of bilateral systems with
constant time delay. This method allows that the slave
manipulator follows the master in spite of the time
delay by means of the state convergence between the
master and the slave. The method is able also to es-
tablish the desired dynamics of this convergence and
the dynamics of the slave manipulator. In this paper,
the control method through state convergence is used
when varying time delays exist in the communication
channel. A constant time delay is considered to ob-
tain the control gains of the system. However these
control gains are applied to control the system when
there are varying time delays. Experimental results
show the validity of the method.
The paper is organized as follows. Section 2 de-
scribes the design and control method of the teleoper-
ation system considering a constant time delay. The
experiments carried out with this control method with
varying time delays are presented in Section 3. Fi-
nally, Section 4 summarizes the conclusions of the
paper.
2 DESIGN AND CONTROL
METHOD OF THE
TELEOPERATION SYSTEM
In this section the modelling of the teleoperation sys-
tem and the control method considering a constant
379
M. Azouın J., Reinoso O., M. Sabater J. and Aracil R. (2004).
CONTROL THROUGH STATE CONVERGENCE OF TELEOPERATION SYSTEMS WITH VARYING TIME DELAY.
In Proceedings of the First International Conference on Informatics in Control, Automation and Robotics, pages 379-382
DOI: 10.5220/0001125603790382
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