Posture Stabilization Control for a Quadruped Robot Walking on Swaying Platforms

Compared to wheeled and tracked robots, legged robots like quadruped robots have much more degrees of freedom, which makes them capable to maintain a constant posture on uneven terrains as well as moving platforms. Previous research has focused on the locomotion of quadruped robots in multiple motionless unstructured environments, while the problem of walking on swaying platforms like the shaking cable bridge is rarely studied. The posture stabilization control on swaying surfaces remains an open problem because of the unpredictability of the external forces and torques acting on the feet caused by the movement of the platform. The main work of this article is to present a method that maps static gaits from stationary rigid platforms to swaying rigid platforms while keeping the torso posture level during the whole walking process. The proposed method can greatly suppress the vibration of the fragile items or attached cameras carried by the robot, which is important in situations such as emergency response. Simulation results confirm the effectiveness of the method proposed.