Stance Phase Leg Actuation Control of the Active SLIP Running Based on Virtual Constraint in Sagittal Plane

Abstract

The Spring Loaded Inverted Pendulum (SLIP), as a versatile template, has been widely used and investigated on legged locomotion control especially in dynamical case. Traditionally, the classic SLIP model is completely passive, which restricts the performance and further application of the model itself. This paper digs into the active SLIP model, namely, the SLIP with leg actuation (SLIP-LA). We concentrate on the stance phase control of the SLIP-LA model. The virtual constraint (VC) of the center of mass (CoM) trajectory in sagittal plane is introduced to generate smooth and continuous motion in stance phase. For ease of implementation on leg actuation, the tracking controller for implicit trajectory is also developed to transform the VC into the polar coordinates. The entire stance controller is ultimately integrated via partial feedback linearization. The effectiveness of the proposed control strategy is demonstrated through the running performance evaluation.