Modeling and analysis of sliding passive dynamic walking with semicircular feet considering impulsive frictional effect

Abstract

This paper discusses the condition necessary for achieving stable sliding passive-dynamic walking of a compass-like biped robot with semicircular feet, and analyzes the fundamental gait properties through numerical simulations. First, we introduce the semicircular-footed compass model and develop the equation of motion, holonomic constraint condition, and equation of collision considering the effect of impulsive frictional force. The paradox in transformation of the impulsive frictional force effect is also discussed. Second, we numerically show that short- and long-period sliding passive compass gaits can be generated under the same condition except the initial condition, and the sliding directions of the fore foot immediately after impact in the two gaits are different from each other. Furthermore, we conduct parametric studies to understand the change tendency of the fundamental gait properties with respect to the system parameters such as the foot radius and frictional coefficient. The simulation results show that the effect of semicircular feet makes it possible for the passive biped to walk on slippery downhill stably in the absence of the hip-damper.