The analysis on bifurcation and chaos in the compass-gait biped

The paper focuses on the analysis of the behavior of symmetric and asymmetric passive gaits using a simple nonlinear gait biped model and also continues the investigation into the stability property of the compass gait biped. Three parameters, namely the ground slope angle, and the mass ratio and length ratio of the robot are used here to observe the target gait property to improve the robot performance as well as generating new gaits. In response to a continuous change in any one of these three parameters, the symmetric and steady gait of the passive robot will gradually evolve through a regime of stable gait, period-doubling bifurcation, and eventually arriving at an apparently chaotic gait. The note of orbital stability is used to study the stability of passive gaits, and Eigen-values of the linearized poincare map are solved to describe the stability property of biped locomotion. Some symmetry properties of the passive gait biped are discussed, to find the degree of asymmetric between two leg´s motions. Period-doubling bifurcation of passive gaits and chaotic gaits is studied by poincare maps of passive gaits. The results of the paper are helpful to the investigation of the features and control strategy design of biped locomotion.