Periodic motion patterns and walking efficiency in a fully actuated biped model

Abstract To ensure stable motion of the biped robot on horizontal ground, a fully actuated walking dynamics model is employed, incorporating heel impulse thrust on the support leg along with actuation torques at the hip and ankle joints. A controlled Poincaré map is obtained by linearising the continuous dynamics. The existence and stability of periodic motion is studied by the Poincaré map. Moreover, the flip bifurcation triggering the route from period-1 motion to chaos is investigated. In addition, the walking efficiency of the fully actuated biped is analysed using the ratio of speed to cost of transport as an indicator. Both analytical derivation and numerical results confirm the stability of period-1 and period-2 gaits in the biped model. By distributing the torques reasonably, there exists a set of torques that make the energy efficiency of the fully actuated biped model higher than that of the underactuated biped model.