Spontaneous gait transition to high-speed galloping by reconciliation between body support and propulsion

Quadrupeds change their gait patterns in response to locomotion speed to achieve low cost of transport over a wide range of speeds. Understanding the underlying control mechanism is essential to establish a design principle for legged robots that can adaptively generate energy-efficient locomotion patterns. Even decerebrate cats exhibit spontaneous gait transition, suggesting that adaptive gait patterns are generated via decentralized control systems, i.e. central pattern generators and reflexes. Several studies address this issue; however, the essential control mechanism that enables spontaneous transition from low- to high-speed gait is still poorly understood. To address this issue, this work reconsiders the interlimb coordination mechanism by focusing on two fundamental roles of limbs: body support and propulsion. To verify the proposed model, 2D simulations and 3D hardware experiments were conducted. The results indicate that the proposed model enables the robot to spontaneously exhibit gait transition to high-speed galloping and to achieve faster and more energy-efficient locomotion than a bounding gait in 3D hardware experiments.

四足动物会根据运动速度调整步态模式，以在宽泛的速度区间内实现较低的运动能耗。解析其背后的控制机制，对于构建可自适应生成节能运动模式的腿部机器人设计原则至关重要。即便去大脑猫也会表现出自发的步态转换现象，这提示自适应步态模式可通过去中心化控制系统生成，即中枢模式发生器（Central Pattern Generators）与反射机制。已有多项研究针对该问题展开探讨，但目前对于支持从低速步态向高速步态自发转换的核心控制机制，仍缺乏深入认知。为解决这一难题，本研究聚焦四肢的两项核心功能——躯体支撑与推进力产生，重新审视了肢体间的协调机制。为验证所提出的模型，本研究开展了二维仿真实验与三维硬件实物实验。实验结果表明，所提模型可使机器人自发完成向高速疾驰步态的转换，且在三维硬件实验中，其运动速度更快、能耗表现优于腾跃步态。