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Time
Domain Passivity Control
Abstract
One
of the most important issues in haptic interface design is to
achieve stable interaction between the haptic display and the
virtual environment for any operating conditions and for any
virtual environment parameters. Vibration or divergent behavior
caused by the instabilities is very distracting, can damage
the hardware, and in large systems, may even pose a physical
threat to the human operator. The facts that virtual environments
of interest are always non-linear and dynamic properties of
a human operator are always involved, can make it especially
difficult to analyze haptic systems in terms of known parameters
and linear control theories. One fruitful avenue to ensure stable
operation is to use the idea of "Passivity."
Recently,
we proposed a patent pending, energy based, method for controlling
a haptic interface system to ensure stable contract under a
wide variety of operating conditions. System stability is analyzed
in terms of the time-domain definition of passivity. We define
a "Passivity Observer" (PO) which measures energy
flow in and out of one or more subsystems in real-time software.
Active behavior is indicated by a negative value of the PO at
any time. We also define the "Passivity Controller"
(PC), an adaptive dissipative element which, at each time sample,
absorbs exactly the net energy output (if any) measured by the
PO.
Devices
Linear
Haptic Display (LHD)
Fingertip
Haptic Display (FHD)
Publications
(*)
(*)
Note: Most of the BRL
publications are available on-line in a PDF format.
You may used the publication's reference number as a link to the
individual manuscript.
[162]
J.H. Ryu, D.S. Kwon, and B. Hannaford, "Stability Guaranteed
Control: Time Domain Passivity Approach," will be published
in IROS2002.
[159]
B. Hannaford, J.H. Ryu, D.S. Kwon, Y.S. Kim, J.B. Song, 'Testing
Time Domain Passivity Control of Haptic Enabled Systems,'
In "Experimental Robotics 2002: Proceedings of the International
Symposium on Experimental Robotics 2002 (ISER-02)", B. Siciliano
and P. Dario, Ed., Springer Verlag, July 9-12, 2002.
[154]
J.H. Ryu, D.S. Kwon, B. Hannaford, 'Stable
Teleoperation with Time Domain Passivity Control,' Proceedings,
IEEE Intl. Conference on Robotics and Automation, ICRA 2002, Washington,
DC, May 2002, pp1863-1869.
[151]
B. Hannaford, J.H. Ryu, 'Time
Domain Passivity Control of Haptic Interfaces,' IEEE Transactions
on Robotics and Automation, vol. 18, pp. 1-10, February, 2002.
[148]
Y.S. Kim, B. Hannaford, 'Some
Practical Issues in Time Domain Passivity Control of Haptic Interfaces,'
Proceedings IROS 2001, Maui, Hawaii, October 2001.
[138]
B. Hannaford, J.H Ryu, 'Time
Domain Passivity Control of Haptic Interfaces,' Proc. IEEE
Intl. Conference on Robotics and Automation, Seoul, May 2001,
pp1863-1869.
[137]
B. Hannaford, J.H. Ryu, Y.S. Kim, 'Stable
Control of Haptics,' In "Touch in Virtual Environments:
Proceedings USC Workshop on Haptic Interfaces, Feb 23 2001",
Margret McLaughlin, Ed., Prentice Hall, 2001.
[160]
B. Hannaford, J.H. Ryu, D.S. Kwon, Y.S. Kim, J.B. Song, 'Testing
Time Domain Passivity Control of Haptic Enabled Systems,'
Technical Report number UWEETR-2002-0010, 19-July-2002.
[158]
B. Hannaford, J.H. Ryu, 'Passivity
Based Method for stable haptic interaction,' U.S. Patent Application,
2001.
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