Dynamic Locomotion Group, Max Planck Institute for Intelligent Systems, Stuttgart, Germany.
Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany.
Sci Robot. 2022 Mar 16;7(64):eabg4055. doi: 10.1126/scirobotics.abg4055.
Designers of legged robots are challenged with creating mechanisms that allow energy-efficient locomotion with robust and minimalistic control. Sources of high energy costs in legged robots include the rapid loading and high forces required to support the robot's mass during stance and the rapid cycling of the leg's state between stance and swing phases. Here, we demonstrate an avian-inspired robot leg design, BirdBot, that challenges the reliance on rapid feedback control for joint coordination and replaces active control with intrinsic, mechanical coupling, reminiscent of a self-engaging and disengaging clutch. A spring tendon network rapidly switches the leg's slack segments into a loadable state at touchdown, distributes load among joints, enables rapid disengagement at toe-off through elastically stored energy, and coordinates swing leg flexion. A bistable joint mediates the spring tendon network's disengagement at the end of stance, powered by stance phase leg angle progression. We show reduced knee-flexing torque to a 10th of what is required for a nonclutching, parallel-elastic leg design with the same kinematics, whereas spring-based compliance extends the leg in stance phase. These mechanisms enable bipedal locomotion with four robot actuators under feedforward control, with high energy efficiency. The robot offers a physical model demonstration of an avian-inspired, multiarticular elastic coupling mechanism that can achieve self-stable, robust, and economic legged locomotion with simple control and no sensory feedback. The proposed design is scalable, allowing the design of large legged robots. BirdBot demonstrates a mechanism for self-engaging and disengaging parallel elastic legs that are contact-triggered by the foot's own lever-arm action.
腿部机器人的设计者面临着创建机制的挑战,这些机制既要允许高效节能的运动,又要具有强大和简化的控制。腿部机器人的高能耗源包括在支撑机器人质量的静止阶段需要快速加载和高力,以及腿部状态在静止和摆动阶段之间快速循环。在这里,我们展示了一种受鸟类启发的机器人腿部设计,BirdBot,它挑战了对关节协调的快速反馈控制的依赖,并通过内在的机械耦合取代主动控制,类似于自啮合和脱离离合器。一个弹簧肌腱网络在触地时迅速将腿部的松弛段切换到可加载状态,在脚趾离地时通过弹性储存的能量在关节之间分配负载,并协调摆动腿的弯曲。一个双稳态关节在静止阶段结束时调节弹簧肌腱网络的脱离,由静止阶段腿部角度的进展提供动力。我们展示了减少膝关节弯曲扭矩的效果,与具有相同运动学的非离合器、平行弹性腿部设计相比,减少到十分之一,而基于弹簧的顺应性在静止阶段延长了腿部。这些机制使得四台机器人执行器能够在前馈控制下实现双足运动,具有高效节能的特点。机器人提供了一个受鸟类启发的多关节弹性耦合机制的物理模型演示,该机制可以实现自我稳定、强大和经济的腿部运动,具有简单的控制和无传感器反馈。所提出的设计是可扩展的,允许设计大型腿部机器人。BirdBot 演示了一种自啮合和脱离平行弹性腿的机制,该机制由脚的自身杠杆臂作用触发接触。