Robotics and Motion Laboratory (RAMlab), Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA
Robotics and Motion Laboratory (RAMlab), Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.
J R Soc Interface. 2018 Sep 26;15(146):20180455. doi: 10.1098/rsif.2018.0455.
In this paper, we systematically investigate passive gaits that emerge from the natural mechanical dynamics of a bipedal system. We use an energetically conservative model of a simple spring-leg biped that exhibits well-defined swing leg dynamics. Through a targeted continuation of periodic motions of this model, we systematically identify different gaits that emerge from simple bouncing in place. We show that these gaits arise along one-dimensional manifolds that bifurcate into different branches with distinctly different motions. The branching is associated with repeated breaks in symmetry of the motion. Among others, the resulting passive dynamic gaits include walking, running, hopping, skipping and galloping. Our work establishes that the most common bipedal gaits can be obtained as different oscillatory motions (or nonlinear modes) of a single mechanical system with a single set of parameter values. For each of these gaits, the timing of swing leg motion and vertical motion is matched. This work thus supports the notion that different gaits are primarily a manifestation of the underlying natural mechanical dynamics of a legged system. Our results might explain the prevalence of certain gaits in nature, and may provide a blueprint for the design and control of energetically economical legged robots.
在本文中，我们系统地研究了从双足系统的自然机械动力学中出现的被动步态。我们使用了一个简单的弹簧腿双足的能量守恒模型，该模型表现出明确的摆动腿动力学。通过对该模型的周期性运动进行有针对性的延续，我们系统地确定了从简单的原地弹跳中出现的不同步态。我们表明，这些步态沿着分叉成具有明显不同运动的不同分支的一维流形出现。分支与运动的对称性的反复破坏有关。其中，产生的被动动态步态包括行走、跑步、跳跃、跳跃和疾驰。我们的工作表明，最常见的双足步态可以作为具有单个参数值的单个机械系统的不同振荡运动（或非线性模式）获得。对于这些步态中的每一种，摆动腿运动和垂直运动的时间都匹配。因此，这项工作支持了以下观点，即不同的步态主要是腿部系统潜在自然机械动力学的表现。我们的结果可能解释了自然界中某些步态的普遍性，并为设计和控制节能腿部机器人提供了蓝图。
