Planar Biped (1985-1990)
We built the Planar Biped, a planar two-legged running machine, to test the
control of bipedal running using the one-leg algorithms.
The machine has two telescoping legs connected to the body by pivot joints at
the hips. A hydraulic actuator within each leg works in series with a
pneumatic spring. Together, they change the length of the leg and make the leg
compliant along its long axis. The body is an aluminum frame, on which are
mounted hip actuators and computer interface electronics. The arrangement of
body, legs, hips, and actuators provides a means to control the position of the
feet with respect to the body, to generate an axial thrust with each leg, and
to provide hip torques during running.
The algorithms used to control machines that hop on one leg can be extended to
control a planar biped, which runs on two legs. The basic approach is for the
control system to designate an active leg and an idle leg. Because there is
just one active leg at a time, the one-leg algorithms can be used to control
the biped's behavior. These algorithms focus on controlling hopping height,
forward running speed, and body posture. The idle leg is kept short while it
is made ready for the next step. Using this approach, the planar biped runs
with an alternating gait or a hopping gait, and can change gaits while running.
We have used the planar biped to study locomotion on rough terrain, running at
high speed, and gymnastic maneuvers. The control program that produces a flip
uses open-loop control patterns in conjunction with the algorithms for normal
running.
Images
Video
Publications
- Hodgins, J. 1988. Legged robots on rough terrain: experiments in adjusting
step length. In Proceedings of the IEEE International Conference on
Robotics and Automation Philadelphia, March 1988.
- Hodgins, J. 1989. Legged Robots on Rough Terrain: Experiments in
Adjusting Step Length. Ph.D Thesis, Computer Science, Carnegie Mellon
University, Pittsburgh, Pennsylvania.
- Hodgins, J. 1991, Biped gait transitions. In Proceedings of the IEEE
International Conference on Robotics and Automation Sacramento.
- Hodgins, J., Raibert, M. H. 1987. Planar Biped Goes Head Over Heels. In
Proceedings ASME Winter Annual Meeting Boston, December, 1987.
- Hodgins, J., Raibert, M. H. 1987. Biped Gymnastics, In Fourth
International Symposium of Robotics Research, B. Bolles, B. Roth (eds.),
(MIT Press, Cambridge).
- Hodgins, J., Raibert, M. H. 1990. Biped gymnastics, International J.
Robotics Research, 9:(2) 115--132.
- Hodgins, J., Raibert, M. H., 1991. Adjusting step length for rough terrain
locomotion, IEEE J. Robotics and Automation.
- Hodgins, J., Koechling, J., Raibert, M. H. 1986. Running experiments with
a planar biped. Third International Symposium on Robotics Research, G.
Giralt, M. Ghallab (eds.). (MIT Press, Cambridge).
- Hodgins, J., Koechling, J., Raibert, M. H. 1991. Running Experiments with
a Planar Biped, CMU Computer Science 25th Anniversary\/,
Addison-Wesley: New York.
- Koechling, J. The Limits of Running Speed: Experiments with a Legged
Robot. Ph.D Thesis, Department of Mechanical Engineering, Carnegie Mellon
University, Pittsburgh, Pennsylvania, 1989.
- Koechling, J. and Raibert, M. 1988. How fast can a legged robot run? In:
Symposium in Robotics, DSC-Vol{.\thinspace11, K. Youcef-Toumi, H.
Kazerooni (eds.). (American Society of Mechanical Engineers, New York).
- Thompson, C. M., Raibert, M. H., 1989. Passive dynamic running, In
International Symposium of Experimental Robotics, Hayward, V., Khatib, O.
(eds.), (Springer-Verlag, New York).
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1995 MIT Leg Laboratory. All Rights Reserved.
Most recent update: 11/16/95