Dynamics and energetics of a class of bipedal walking systems

The mechanical analysis of bipedal walking is a fundamental subject of research in biomechanics. Such analysis is useful to better understand the principles underlying human locomotion, as well as to improve the design and control of bipedal robotic prototypes. Modelling the dynamics of walking involves the analysis of its two phases of motion: (1) the single support phase, which represents finite motion; and (2) the impulsive motion of the impact that occurs at the end of each step (heel strike). The latter is an important event since it is the main cause of energy loss during motion and, in turn, it makes the topology of the system change. In this paper, we present a unified method to analyze the dynamics of both phases of walking. Emphasis is given to the heel strike event, for which we introduce a novel method that gives a complete decomposition of the dynamic equations and the kinetic energy of the system at topology change. As an application example, the presented approach is applied to a compass-gait biped with point feet. Based on this, the work includes a thorough analysis and discussions about the effect of the biped configuration and its inertial parameters on the dynamics and energetics of heel strike.