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Control of Passive Dynamics

Design for passive dynamics appears to be necessary on the path towards energy efficient practical legged robots. However, robots with proper passive dynamics are either unstable or if there is a stable limit cycle, its domain of attraction is typically small. Interpreting locomotion as a periodically forced limit cycle oscillation of a highly nonlinear dynamical system, control forcing functions are developed which stabilize the limit cycle over a large region of phase space, consume minimal energy, an provide strong robustness to modeling error, noise and external disturbances. In the absence of accurate models of contact, material deformation, noise and actuator dynamics, physical experimentation is mandatory. Based on encouraging simulation results we are now implementing our passive dynamic design and control ideas on the ARL Monopod.

M. Ahmadi, M. Buehler

ARL Monopod

Thierry Baron
Mon Nov 13 10:43:02 EST 1995