Walk-Trot-Gallop Transition with Spinal Flexion in a Quadruped Model

Quadruped animals change their gait patterns in response to speeds, such as walk, trot and gallop. Previous studies have considered that gait transitions contribute to energy efficiency or locomotor stability. Understanding the control mechanism underlying speed-dependent gait transition contributes to developing the control principle providing legged robots with animal-like agility. Quadruped gaits involve coordinated movements of legs, trunk, head and tail. This sophisticated behavior is mainly controlled by a distributed control system comprising of central pattern generators textasciitilde (CPGs) and peripheral sensory feedback. Modeling studies presented that CPG-based controller with local sensory feedback can coordinate four-leg movements and achieve speed-dependent gait transition. However, the whole-body coordination mechanisms in speed-dependent gait transition remain elusive. This study investigated the whole-body coordination mechanisms in speed-dependent gait transitions through mathematical modeling and simulations. This paper proposes a quadruped model that generates speed-dependent gait transitions incorporating trunk movements. The simulation results demonstrated that local communication of sensory information achieved self-organized movements and walk-trot-gallop gait transition.