Exploiting natural dynamics for gait generation in undulatory locomotion

ABSTRACTRobotic vehicles inspired by animal locomotion are propelled by interactive forces from the environment resulting from periodic body movements. The pattern of body oscillation (gait) can be mimicked from animals, but understanding the principles underlying the gait generation would allow for flexible and broad applications to match and go beyond the performance of nature's design. We hypothesize that the traveling-wave oscillations, often observed in undulatory locomotion, can be characterized as a natural oscillation of the locomotion dynamics, and propose a formal definition of the natural gait for locomotion systems. We first identify the dynamics essential to undulatory locomotion, and define the mode shape of natural oscillation by the free response of an idealized system. We then use body-environment resonance to define the amplitude and frequency of the oscillations. Explicit formulas for the natural gait are derived, assuming uniformity of the body, to provide insight into the mechanisms u...