Imperial College London, London SW7 2AZ, UK.
IEEE Trans Cybern. 2013 Jun;43(3):1131-45. doi: 10.1109/TSMCB.2012.2224920. Epub 2012 Nov 10.
Bipedal walking is not fully understood. Motion generated from methods employed in robotics literature is stiff and is not nearly as energy efficient as what we observe in nature. In this paper, we propose validity conditions for motion adaptation from biological principles in terms of the topology of the dynamic system. This allows us to provide a closed-form solution to the problem of motion adaptation to environmental perturbations. We define both global and local controllers that improve structural and state stability, respectively. Global control is achieved by coupling the dynamic system with a neural oscillator, which preserves the periodic structure of the motion primitive and ensures stability by entrainment. A group action derived from Lie group symmetry is introduced as a local control that transforms the underlying state space while preserving certain motor invariants. We verify our method by evaluating the stability and energy consumption of a synthetic passive dynamic walker and compare this with motion data of a real walker. We also demonstrate that our method can be applied to a variety of systems.
双足行走尚未完全被理解。机器人文献中采用的运动生成方法是僵硬的，其能量效率远不及我们在自然界中观察到的。在本文中，我们根据动力系统的拓扑结构，提出了从生物原理进行运动适应的有效性条件。这使我们能够为适应环境干扰的运动问题提供一个闭式解。我们分别定义了全局控制器和局部控制器，以分别提高结构和状态稳定性。全局控制是通过将动力系统与神经振荡器耦合来实现的，神经振荡器保留了运动基元的周期性结构，并通过同步确保稳定性。作为局部控制，我们引入了由李群对称性导出的群作用，它在保持某些运动不变量的同时变换基础状态空间。我们通过评估合成被动动态步行者的稳定性和能量消耗来验证我们的方法，并将其与真实步行者的运动数据进行比较。我们还证明了我们的方法可以应用于各种系统。
