Bifurcation and chaos of a biped robot driven by coupled elastic actuation

Bifurcation and chaos are found and studied in-depth in passive dynamic walking long before, but relative report and research in passive-based powered biped walking is quite few. We study the walking behavior of the powered biped walking model based on compass-like gait robot in detail. This model is driven by coupled elastic actuation which has the `motor, actuated bar and spring´ structure. It is found that this powered model shows bifurcation and chaos as physical and control parameters change continuously just like the passive model, and new gait evolution that has an reverse process from chaos back to period-doubling with respect to physical parameter of the spring coefficient is discovered and studied. In addition, the double-gait and fractal phenomenon are found and discussed. This study aims to reveal the change rules of the walking behavior with respect to physical and control parameters and the properties of the dynamics of the powered model, so as to provide the theoretical foundation for the control of the robot.