提出新运动协调规律，助力假肢更省力行走
Extending the Law of Intersegmental Coordination: Implications for Powered Prosthetic Controls
- 基于关节角度与力矩构建3D运动协调分析方法
- 发现健全人步态存在力矩协同规律，截肢者则缺失
- 设计基于健康模式的假肢控制框架，可降低能耗
主动式假肢虽能提供净正功，但降低截肢者步行代谢成本仍是难题。以往观察到的肢体段间协调定律（ISC）涉及大腿、小腿和脚在步态周期中角度的共变关系。本文开发了一种分析下肢三维运动数据中段间协调的方法，简化了ISC分析流程。受运动控制、生物力学和机器人学启发，我们进一步将ISC扩展为新的力矩协调规律——高度空间力矩（ESM）。结果显示，健全人步态中存在力矩协同；而使用被动或主动假肢的截肢者，其角度仍保持平面协调，但力矩却无此特性。为此，我们提出一种基于健康协调模式的主动假肢控制框架，通过预测小腿角度/力矩来补偿被动足带来的变化。同时发布了ISC3d开源工具箱，可用于计算3D运动学与动力学中的ISC，有助于深入研究步态协调机制及其对神经控制的影响。
原文摘要 · Abstract (English)
Powered prostheses are capable of providing net positive work to amputees and have advanced in the past two decades. However, reducing amputee metabolic cost of walking remains an open problem. The Law of Intersegmental Coordination (ISC) has been observed across gaits and previously implicated in energy expenditure of walking, yet it has rarely been analyzed or applied within the context of lower-limb amputee gait. This law states that the elevation angles of the thigh, shank and foot over the gait cycle covary. In this work, we developed a method to analyze intersegmental coordination for lower-limb 3D kinematic data, to simplify ISC analysis. Moreover, inspired by motor control, biomechanics and robotics literature, we used our method to extend ISC to a new law of coordination of moments. We find these Elevation Space Moments (ESM), and present results showing a moment-based coordination for able bodied gait. We also analyzed ISC for amputee gait with powered and passive prostheses, and found that while elevation angles remained planar, the ESM lacked planar coordination. We present an ISC-driven powered prosthetic control framework, using healthy coordination as a constraint to predict the shank angles/moments to compensate for alterations due to a passive foot. We developed the ISC3d toolbox that is freely available online, which may be used to compute kinematic and kinetic ISC in 3D. This provides a means to further study the role of coordination in gait and may help address fundamental questions of the neural control of human movement.
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