In this paper we compare models and experiments involving Scout II, an untethered four-legged running robot with only one actuator per compliant leg. Scout II achieves dynamically stable running of up to 1.3 m s-1on flat ground via a bounding gait. Energetics analysis reveals a highly efficient system with a specific resistance of only 1.4. The running controller requires no task-level or body-state feedback, and relies on the passive dynamics of the mechanical system. These results contribute to the increasing evidence that apparently complex dynamically dexterous tasks may be controlled via simple control laws. We discuss general modeling issues for dynamically stable legged robots. Two simulation models are compared with experimental data to test the validity of common simplifying assumptions. The need for including motor saturation and non-rigid torque transmission characteristics in simulation models is demonstrated. Similar issues are likely to be important in other dynamically stable legged robots as well. An extensive suite of experimental results documents the robot’s performance and the validity of the proposed models.
Altendorfer, R., Koditschek, D., and Holmes, P. 2004. Stability analysis of legged locomotion models by symmetry factored return maps . International Journal of Robotics Research23(11): 979-1000 .
3.
Battaglia, R. 1999. Design of the Scout II Quadruped with Preliminary Stair Climbing. M.Eng. Thesis, McGill University, Montreal, QC, Canada, May.
4.
Berkemeier, M. D. 1998. Modeling the dynamics of quadrupedal running . International Journal of Robotics Research17(9): 971-985 .
5.
Buehler, M. 2002. Dynamic locomotion with one, four and six-legged robots . Journal of the Robotics Society of Japan20(3): 15-20 .
6.
Buehler, M., Battaglia, R., Cocosco, A., Hawker, G., Sarkis, J., and Yamazaki, K. 1998. SCOUT: a simple quadruped that walks, climbs, and runs . Proceedings of the IEEE International Conference on Robotics and Automation, Leuven, Belgium, May, pp. 1701-1712 .
7.
Campbell, D., and Buehler, M. 2003. Preliminary bounding experiments in a dynamic hexapod. Experimental Robotics VIII, Springer Tracts in Advanced Robotics 5, B. Siciliano and P. Dario, editors, Springer-Verlag, Berlin , pp. 612-621.
8.
De Lasa, M., and Buehler, M. 2001. Dynamic compliant walking . Proceedings of the IEEE International Conference on Robotics and Automation, Seoul, Korea, May, pp. 3153-3158 .
9.
Formalsky, A., Chevallereau, C., and Perrin, B. 2000. On ballistic walking locomotion of a quadruped . International Journal of Robotics Research19(8): 743-761 .
10.
Freeman, P. S., and Orin, D. E. 1991. Efficient dynamic simulation of a quadruped using a decoupled tree-structure approach . International Journal of Robotics Research10(6): 619-627 .
11.
Full, R. J., and Koditschek, D. 1999. Templates and anchors: neuromechanical hypotheses of legged locomotion on land . Journal of Experimental Biology202: 3325-3332 .
12.
Furusho, J., Sano, A., Sakaguchi, M., and Koizumi E. 1995. Realization of bounce gait in a quadruped robot with articular-joint-type legs . Proceedings of the IEEE International Conference on Robotics and Automation, Nagoya, Japan, pp. 697-702 .
13.
Gabrielli, G., and von Karman, T. H. 1950. What price speed? Mechanical Engineering72(10): 775-781 .
14.
Ghigliazza, R. M., Altendorfer, R., Holmes, P., and Koditschek, D. E. 2003. Passively stable conservative locomotion . SIAM Journal of Applied Dynamical Systems2(2): 187-218 .
15.
Herr, H. M., and McMahon, T. A. 2001. A galloping horse model . International Journal of Robotics Research20(1): 26-37 .
16.
Hirose, S. 2001. Super mechano-system: new perspective for versatile robotic system . Experimental Robotics VII, Lecture Notes in Control and Information Sciences 271, D. Rus and S. Singh, editors, Springer-Verlag, Berlin, pp. 281-289 .
17.
Kimura, H., Akiyama, S., and Sakurama, K. 1999. Realization of dynamic walking and running of the quadruped using neural oscillator . Autonomous Robots7(3): 247-258 .
18.
Knowledge Revolution. 1996. Working Model 2D User’s Guide, Version 5.0, San Mateo, CA (http://www.krev.com).
19.
Kubow, T. M., and Full, R. J. 1999. The role of the mechanical system in control: a hypothesis of self-stabilization in hexapedal runners . Philosophical Transactions of the Royal Society of London Series B - Biological Sciences354(1385): 854-862 .
20.
McGeer, T. 1989. Passive bipedal running. Technical Report, CSS-IS TR 89-02, Simon Fraser University, Centre For Systems Science, Burnaby, BC, Canada .
Moore, E. Z. 2002. Leg Design and Stair Climbing Control for the RHex Robotic Hexapod. M.Eng. Thesis, McGill University, Montreal, QC, Canada, January.
24.
Muybridge, E. 1957. Animals in Motion, Dover Publications, New York .
25.
Nichol, J. G., and Waldron, K. J. 2002. Biomimetic leg design for untethered quadruped gallop . Proceedings of the International Conference on Climbing and Walking Robots (CLAWAR), Paris, France, September 25-27, pp. 49-54 .
26.
Papadopoulos, D., and Buehler, M. 2000. Stable running in a quadruped robot with compliant legs . Proceedings of the IEEE International Conference on Robotics and Automation, San Francisco, CA, April 24-28, pp. 444-449 .
27.
Poulakakis, I. 2002. On the Passive Dynamics of Quadrupedal Running. M.Eng. Thesis, McGill University, QC, Canada, July.
28.
Poulakakis, I., Papadopoulos, E., and Buehler, M. 2003. On the stable passive dynamics of quadrupedal running . Proceedings of the IEEE International Conference on Robotics and Automation, Taipei, Taiwan, September 14-19, pp. 1368-1373 .
29.
Poulakakis, I., Smith, J. A., and Buehler, M. 2003. On the dynamics of bounding and extensions towards the half-bound and the gallop gaits . Proceedings of the International Symposium on Adaptive Motion of Animals and Machines, Kyoto, Japan.
30.
Poulakakis, I., Smith, J.A., and Buehler, M. 2004. Experimentally validated bounding models for the Scout II quadruped robot . Proceedings of the IEEE International Conference on Robotics and Automation, New Orleans, LA.
31.
Raibert, M. H. 1986. Legged Robots that Balance. MIT Press, Cambridge, MA .
32.
Raibert, M. H., Brown, H. B. Jr, Chepponis, M., Hodgins, J., Kroechling, J., Miller, J., Murphy, K. N., Murthy, S. S., and Stentz, A. 1985. Dynamically stable legged locomotion. Technical Report, CMU-LL-4-1985, Carnegie Mellon University, The Robotics Institute, Pittsburgh, PA , February.
33.
Saranli, U., Buehler, M., and Koditschek, D. E. 2001. RHex: a simple and highly mobile hexapod robot . International Journal of Robotics Research20(7): 616-631 .
34.
Schmiedeler, J. P., and Waldron, K. J. 1999. The mechanics of quadrupedal galloping and the future of legged vehicles . International Journal of Robotics Research18(12): 1224-1234 .
35.
Seyfarth, A., Geyer, H., Guenther, M., and Blickhan, R. 2002. A movement criterion for running . Journal of Biomechanics35: 649-655 .
36.
Song, S-M., and Waldron, K. J. 1989. Machines That Walk: The Adaptive Suspension Vehicle. MIT Press, Cambridge, MA .
37.
Talebi, S. 2000. Compliant Running and Step Climbing of the Scout II Platform. M. Eng. Thesis, McGill University, Montreal, QC, Canada, November.
38.
Talebi, S., Poulakakis, I., Papadopoulos, E., and Buehler, M. 2001. Quadruped robot running with a bounding gait. Experimental Robotics VII , Lecture Notes in Control and Information Sciences 271, D. Rus and S. Singh, editors, Springer-Verlag, Berlin, pp. 281-289 .
39.
Yamamoto, Y., Fujita, M., De Lasa, M., Talebi, S., Jewell, D., Playter, R., and Raibert, M. 2001. Development of dynamic locomotion for the entertainment robot - teaching a new dog old tricks . Proceedings of the 4th International Conference on Climbing and Walking Robots (CLAWAR), Karlsruhe, Germany, September 24-26, pp. 695-702 .
