Control strategy for energy-efficient bipedal walking with variable leg stiffness

In this work, we propose a hybrid model for a bipedal walker with controlled variable leg stiffness, and a control strategy for stable gait control. The control reference is a passive gait of the limit-case bipedal spring-loaded inverted pendulum model with massless feet, ensuring that the gait is close to the ideal passive gait and thus aiming for energy efficiency. The effectiveness of the controller is demonstrated with numerical simulation results. From the results a theoretical cost of transport is calculated, showing that the control strategy is indeed energy efficient.