Energetic walking gaits studied by a simple actuated inverted pendulum model

The mechanical structure and the joint torques configuration are the important parts in the biped robot design. Meanwhile, different walking speed and step length should be chosen to achieve efficient gait according to different need of walking environment. Therefore, this paper investigates the energetic walking gaits using a simple actuated inverted pendulum model. Joint torques and push-off impulse are both added in the model. The walking gaits with different joint torques configuration and with different combination of walking speeds and step lengths are analyzed. The results show that hip velocity direction is changed by the push-off impulse just before the heelstrike, which reduces the energy consumption of each step. The walking gait with minimal energy consumption is the walking pattern only with push-off, the energy cost of which is 1/4 of the walking pattern only with joint torque during the swing phase. The cost of transport (COT) and the push-off impulse of the walking gait is increasing with the increase of walking speed and step length. Using same value of push-off impulse, the walking with long step length and slow speed is more efficient. The paper can provide suggestions for designing advanced legged robot systems with high energy efficiency and various gaits. For example, the consideration of push-off mechanism can be used in the biped robots design.