A Hybrid Impedance and Admittance Control Strategy for a Shape-Transformable Leg-Wheel

Abstract

In this study, a hybrid impedance and admittance control strategy is developed as a low-level, high-speed controller for legged robots that fuses two controllers within the range of several ticks of a control loop. This strategy enables the rigid-link legs not only to have accurate motion trajectories but also to adapt to the impacts caused by interactions with unknown environments. In addition, owing to the significantly different characteristics of the leg in compression and in tension, the study introduces a novel switching strategy that adjusts the hybrid level of the controller in the range of the leg stride. The proposed strategy was experimentally validated on a linkage-based leg wheel, and the results confirm the effectiveness of the strategy.