Optimal design and implementation of an energy-efficient, semi-active biped

In this paper, a semi-active biped which combines the merits of both powered and passive bipeds is proposed. The semi-activeness of the biped is due to the fact that, during most of a walking cycle, only half of the joints are actuated, and the other half remain unactuated, but have passive joint springs to induce their motions. To devise a systematic design methodology for the biped, its dynamics as well as the walking constraints are carefully studied. Furthermore, an optimization procedure is proposed to compute the optimal trajectories for the actuated joints and spring constants which can lead to minimum energy consumption. The feasibility of the proposed biped is verified by hardware implementation. Experiments indicate that the semi-active biped consumes 80% less the electrical power of the powered biped that performs the same gait and is more energy-efficient than several state-of-the-art bipeds.