Decentralized Intra-Limb Coordination Mechanisms Toward Whole-Body Coordinated Quadruped Locomotion

Intra-limb coordination is fundamental for legged locomotion, enabling navigation of rough terrain, generation of propulsive forces, and maintenance of stability 1. Modeling studies have investigated the underlying mechanisms through three primary approaches: decentralized control, employing Central Pattern Generators (CPGs) 2 or reflex-based systems for pattern generation 3; centralized control, often utilizing reinforcement learning 4; and biomechanical analysis, exploring the intrinsic dynamics of the body 5. However, these previous studies focused on limbs, often with limited attention to the influence of other body parts, such as the trunk and head. To gain a more holistic understanding of how limbs coordinate, it is crucial to investigate the interplay between limbs and the entire body. Therefore, this study investigates the mechanisms of intra-limb coordination, incorporating whole-body coordination. We employ mathematical modeling and simulation to elucidate this interplay. Our previous work presented a decentralized control scheme for a 2D quadruped model, demonstrating inter-limb and body-limb coordination and replicating various gaits 6. Building upon this work, we propose an extended model that integrates a decentralized control mechanism for intra-limb coordination. The results show the ability of this whole-body coordination model to reproduce the walking gait observed in quadrupeds.