复杂路面条件下膝上假肢系统刚柔耦合动力学建模及顺应性研究

Walking with the prosthesis is one of the international frontier research topics in the field of biomechanics. For above knee amputees, the major problems include unstable gaits and falling down when walking on uncertain road surfaces. The drawbacks of the mechanical properties of prostheses are the main reasons for these problems. Therefore, the prostheses require the optimal design based on dynamic models and vibration characteristics. This project is based on our previous study about stability analysis of prosthetic feet walking on the level ground. The aim of this project is to study the rigid-flexible coupling dynamic model and the compliance of the above-knee prosthesis under complex road conditions. Firstly, the absolute nodal coordinate formulation (ANCF) is used to develop the rigid-flexible coupling dynamic model of an above-knee amputee with the prosthesis. The uncertain boundary constraints are included via equations of compliant ground-foot contact. Secondly, the dynamic characteristics of contact and vibration of the system including prosthetic knee joint with clearance are investigated for walking on uncertain road surfaces. Finally, based on the principles of energy distribution and stiffness matching, the index is proposed to evaluate the compliance of the system. The compliance index is used to design optimal above-knee prostheses with adaptation to typical road surface conditions. And the verification test is conducted. The meaning of this project is to explore the inherent law of the ground-foot impacts. It can also enrich the theory of the mechanism underlying ambulation of lower limb amputees with prostheses. This research is helpful to study the functional evaluation and optimal design of above-knee prostheses, and to manufacture the new prostheses with adaptation to complex road conditions. In conclusion, this project has an important theoretical and applicable significance.

穿戴假肢行走是国际生物力学领域的研究热点和前沿，当前重要问题是穿戴者在复杂路面行走容易步态失稳甚至摔倒，主要原因是由于假肢机械机构自身性能存在缺陷，问题的解决依赖于在假肢动力学建模和振动特性研究基础上进行优化设计。 本项目立足国际前沿，以前期对踝足假脚在平坦地面行走稳定性研究为基础，研究复杂路面下膝上假肢系统刚柔耦合动力学建模及顺应性。首先，基于绝对节点坐标法，引入假脚与地面不确定性边界约束条件，建立系统刚柔耦合动力学模型；然后，研究变载荷、变路面条件下含假肢膝关节间隙铰的系统接触碰撞动力学特性及振动特性；最后，基于能量分配和刚度匹配提出膝上假肢顺应性评价指标，研究典型路面下假肢优化设计方案，并进行验证实验。项目的科学意义在于揭示假肢与不同路面接触碰撞规律，丰富人体穿戴假肢运动机理理论；研究成果对推动假肢功能评价和优化设计、研制适应复杂路面的新型膝上假肢，具有重要理论意义及实际应用价值。

穿戴假肢行走是国际生物力学领域的研究热点和前沿，当前重要问题是假肢穿戴者在复杂路面行走容易步态失稳甚至摔倒，主要原因是假肢机械机构自身性能存在缺陷，因而假肢的动力学建模、振动特性研究以及优化设计是亟待解决的问题。本项目立足国际前沿，在前期对踝足假脚在平坦地面行走稳定性研究的基础上，对复杂路面条件下人体穿戴膝上假肢刚柔耦合动力学模型建立、假脚与路面接触碰撞和假肢顺应性的实际问题进行了深入的研究。首先，我们基于绝对节点坐标法，建立考虑假肢膝关节间隙的人体穿戴单侧膝上假肢系统刚柔耦合动力学模型；其次，我们基于遗传算法及遗传算法与人工神经网络结合的算法对双足机器人在平地、上下坡、上下楼梯的步态轨迹进行优化，对4种不同假脚穿戴者以不同速度行走时的轨道稳定性进行分析；然后，我们研究了脚与复杂路面（斜坡、楼梯、横沟）的接触碰撞特性及假肢的振动特性；最后，我们基于能量匹配准则，对膝上假肢的顺应结构进行分析，提出膝上假肢优化设计方案。本项目的科学意义在于揭示假肢与不同复杂路面接触碰撞规律，丰富人体穿戴假肢运动机理理论；研究成果对推动假肢功能评价和优化设计、研制适应复杂路面的新型膝上假肢，具有重要理论意义及实际应用价值。