Dynamics of gait transitions
Dynamics of gait transitions
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发表时间：
2011
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通讯作者：
P. Aerts;V. Segers;S. Nauwelaerts;K. D’Août;I. V. Caekenberghe;P. Fiers;P. Malcolm;D. Clercq
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作者：
P. Aerts;V. Segers;S. Nauwelaerts;K. D’Août;I. V. Caekenberghe;P. Fiers;P. Malcolm;D. Clercq
尽管许多研究都涉及步态之间的转换，并提供了一些关于最终和近似原因的替代假设，但令人惊讶的是，关于从一种步态转换到另一种步态时实际发生的运动学和动态变化的信息很少。然而，这类基本信息对于进一步了解过渡的控制和推测近因触发的性质似乎是必不可少的。由于步态转换通常发生在全身加速过程中，因此在地面上进行研究。我们测量了人体从步行到跑步的整个过渡过程中的3D运动学、地面反作用力和（在有限的一组实验中）肌肉激活模式（反之亦然；通常在过渡前3步和后3步）。使用了三种实验条件：持续加速（控制速率），自发加速期间和执行突发过渡（逃离）时。除了描述性运动学和力之外，还计算了全身动力学和关节动力学来描述过渡。比较过渡到不常见的两足疾驰步态在人类和小跑-中心过渡在四足动物。在一项平行研究中，一个动力足踝外骨骼被用来探索下肢肌肉在触发人类从步行到跑步过渡中的潜在作用。在有腿机器人的发展背景下，能够根据环境自主地在步态之间切换（例如，为了利用执行器的顺应性而转向更动态的步态），从自然中获得的见解可能非常有用。
Although many studies deal with transitions between gaits and several alternative hypotheses on ultimate and proximate causes are provided, surprisingly little information is available on what actually happens kinematically and dynamically when changing from one gait to the other. Nevertheless, this kind of basic information seems indispensible for further insights in the control of transition and to speculate on the nature of proximate triggers. As gait transitions typically occur during whole body accelerations, they are studied overground. We measured 3D kinematics, ground reaction forces and (in a limited set of experiments) muscle activation patterns in humans throughout transition from walking to running (and vice versa; typically 3 steps before and 3 steps after the transition). Three experimental conditions are used: accelerating constantly (controlled rate), during spontaneous accelerations and when performing a burst transition (fleeing). Next to the descriptive kinematics and forces, whole body dynamics and joint dynamics are calculated to characterize the transitions. Comparisons with transitions towards the uncommon bipedal galloping gait in humans and with trot-canter transitions in quadrupeds are made. In a parallel study, a powered foot-ankle exoskeleton is used to explore to potential role of lower limb muscles in triggering the walk to run transition in humans. In the context of the development of legged robots, able to switch autonomously between gaits according the circumstance (e.g. towards more dynamic gaits in order to exploit actuator compliance), insights gained from nature may be very useful.