Bio-inspired Multi-Model Fusion Control for CPG-based Quadrupedal Locomotion

To promote the deployment of quadrupedal robots, this study proposes a novel bio-inspired control scheme. Specifically, inspired by the differentiated modalities of the animal's proximal and distal joints, a multi-model fusion scheme is constructed. First, the hip movement in joint space is obtained by a central pattern generator(CPG), whereby motion gaits, including trotting and galloping, are generated by a coupling network. Then, to generate the knee motion, a CPG-driven finite state machine is first proposed to determine the gait state. On top of this, the spring-loaded inverted pendulum model is utilized to regulate the knee joint's torque command. Furthermore, to enhance stability, online feedback regulation is incorporated to regulate CPG behavior. And, a virtual model control strategy is designed to modify the torque profile of the knee torque. To verify the proposed methodology, hardware experiments are conducted on a newly developed quadrupedal robot. Results demonstrate that \textit{i)} the small-sized robot can reach 0.8 m/s, with high tracking performance; \textit{ii)} compared with the traditional case where CPG generates both hip and knee trajectory directly, the energy consumption is reduced by 11.2\% with our method; \textit{iii)} the robot can realize smooth gait transition on flat ground and robust walking across uneven terrains.