球面外骨骼并联机构的运动学及工作空间分析

本文基于生物力学模型开源软件OpenSim生物力学仿真曲线,针对腿部运动功能受损的患者或患有行走功能障碍的老年人的康复治疗,提出了一种2自由度的球面髋关节外骨骼并联机构。首先,对并联机构进行建模,通过逆运动学分析得到机构的位置反解,对反解进行求导,推导出该机构的速度分析表达式。将模型分别导入机械系统动力学分析软件ADAMS与矩阵处理分析软件MATLAB中进行仿真实验,通过两者的速度仿真结果比较,验证了速度分析的正确性。然后,根据获取的雅可比(Jacobian)矩阵对该机构进行了3种奇异位型分析,根据机构反解在MATLAB中编程,给定机构参数与限制条件,获得该机构的可达工作空间。最后,构建原理样机实验平台。实验结果表明,外骨骼髋关节采用这种并联机构,能够满足人体髋关节的运动转动角度要求,也可以协助患者较好地进行腿部的前屈后伸运动和外展内收运动,有助于开展相应的康复训练,并且对人体髋关节外骨骼并联机构的研究也具有理论意义与应用价值。     

计及舒适性的膝关节外骨骼机器人张弛穿戴系统性能优化及方法研究

为了提高穿戴舒适性与承载有效性，本文在提出一种膝关节外骨骼机器人张弛穿戴系统原型及其工作机制解析的基础上，对该系统开展静力学优化综合及其方法研究。首先，本文基于系统虚拟样机模型的构建，构造一种计及应力、变形及受力结点占比等要素的综合穿戴舒适度评价指标；其次，基于系统虚拟样机静力学仿真，结合评价指标，开展多目标遗传优化与铠甲层拓扑构型的局部优化综合；最后，通过模型重建仿真数据证实了该系统具有良好的穿戴舒适性。本研究为后续穿戴系统的承载性能及样机建造提供了理论基础。     

足部有限元模型的构建与验证

背景：目前国内所建的足部模型大部分是采用自动划分网格的四面体有限元模型,虽然四面体网格自动剖分技术给三维实体的有限元网格自动剖分带来了极大的方便,但力学性能较差。 目的：基于CT图片构建六面体网格足部有限元模型。 方法：选取中国正常男性人体足部的CT数据,利用Mimics软件对足部几何模型进行重构,运用NURBS 曲面的节点插入算法,对足部几何模型进行了细化,构建了具有较高生物仿真度的人体足部有限元模型,利用Pam-crash软件对模型进行了碰撞仿真分析。 结果与结论：仿真结果与尸体实验结果基本一致,证明模型可信。实验基于CT图片构建的六面体网格足部有限元模型,添加了足底肌肉、肌腱、皮肤等结构,更真实的反映了足部解剖学结构特征,进而提高了有限元模型的质量,更能有效地研究足部损伤机制,从而为提高汽车安全性设计提供参考依据。     

假肢膝关节机构的多目标优化设计

背景：如何实现穿戴者的舒适性、运动的灵活性一直是假肢膝关节研究的焦点。 目的：分析膝关节运动过程的瞬心规律,构造合适的评价函数,使其更好地满足穿戴者舒适与自然的要求,进而得到假肢膝关节结构参数。 方法：选取假肢膝关节四连杆机构作为研究对象,建立机构运动学模型,并利用三心定理,推导出连杆瞬心轨迹。考虑穿戴者运动的舒适性,建立了打分系统模型作为评价函数。进一步考虑假肢运动的自然性,以膝盖弯曲过程中实际瞬心与理想瞬心总偏差最小,以及上述的评价函数最大值作为双重优化目标,以假肢膝关节机构仿生学约束、双摇杆机构尺寸约束作为约束条件,建立多目标优化模型。 结果与结论：运用主要目标法,并通过MATLAB编程得到了优化后的假肢膝关节机构的参数。所设计的四杆机构较好地协调了假肢穿戴者的舒适性与运动的自然性。      

基于机械系统动力学自动分析的步态仿真足部分块模型

本文旨在建立适用于步态动力学仿真分析的足部分块模型并验证其有效性及实用性。本文基于新型的混合驱动人体步态试验机,将骨骼模型导入机械系统动力学自动分析软件(ADAMS)中,结合在其中建立的足部韧带、筋膜、肌肉模型及柔性体足底软组织模型,组成足部分块模型。用在体试验采集到的步态数据作为驱动,并在模型上加载肌肉力和肌腱力,进行步态模拟。将得到的地面反作用力及关节旋转角度与报道结果进行比较,验证了模型的有效性。本文仿真结果表明,本模型能较好地用于步态动力学仿真分析,并有望作为进一步研究的工具。     

足部三维有限元建模方法及其生物力学应用

目的探讨建立足部三维有限元模型的方法,应用模型模拟分析研究鞋垫设计参数,不同软组织刚度和受力情况下对足部的生物力学影响。方法建立基于解剖结构,包括软组织,韧带和腱膜,考虑材料的非线性和关节接触的足部三维有限元模型。有限元模型的可靠性利用模拟足踝关节在不同病理、手术和鞋垫矫治情况下的生物力学反应来验证。结果有限元分析结果表明,定制型鞋垫的形状比鞋垫材料的刚度对减少足底最大压力有更重要影响。软组织刚度的增加引起足底接触面积的减小,从而会导致足底跖骨区最大压力增加。部分和完全松解足底腱膜都会降低足弓高度,并增加足底韧带的张力和增加中足和跖骨的应力。体重增加和跟腱拉力增加都将成倍足底筋膜的拉力。结论所建足部有限元模型能预测足底压力分布和足内部骨骼软组织应力、应变情况,可以成为设计鞋垫和研究足部各种临床状况提供有力的分析工具。     

穿戴式下肢外骨骼对人体步态特性的影响研究

本文拟探明穿戴式下肢外骨骼对人体下肢相应关节参数与肌肉运动学、动力学参数的影响变化,进而为优化其结构、提高其系统性能提供科学依据。本文通过采集受试者的行走数据,以人体下肢各关节在矢状面上的关节角度作为下肢外骨骼仿真分析的驱动数据,运用人体生物力学分析软件Anybody分别建立了人体模型(即未穿戴下肢外骨骼的人体模型)和人-机系统模型(即穿戴下肢外骨骼后的模型),并对比分析了两种情况下人体下肢运动时的运动学参数(关节力、关节力矩)及肌肉参数(肌肉力、肌肉激活程度、肌肉收缩速度、肌肉长度)的变化情况。实验结果表明,人体穿戴下肢外骨骼后行走的步态满足正常步态,但会出现个别肌肉力突增的现象;下肢主要肌肉的最大肌肉激活程度均未超过1,说明肌肉均未出现疲劳或损伤状况;股直肌的最大肌肉激活程度增加最多(0.456),半腱肌的最大肌肉激活程度增加最少(0.013),提示下肢外骨骼最容易引起股直肌疲劳或损伤。通过本文研究结果说明,为避免出现个别肌肉力突增导致人体下肢损伤,在设计下肢外骨骼时,要特别注意人体体段长与下肢外骨骼杆长的一致性和运动的平稳性。     

基于最优拉丁超立方设计的糖尿病足鞋垫优化设计

目的 提出一种鞋材弹性模量与厚度联合优化设计糖尿病足鞋垫的方法,以降低足底压力和软组织内部应力。方法 通过逆向工程方法建立足部有限元模型,基于足底压力分布特征划分鞋垫压力区域,采用有限元法对接触力学进行研究,为优化过程中调整不同区域内材料的弹性模量和鞋垫前后足厚度奠定基础,使用最优拉丁超立方设计得到最优参数组合。结果 设计的鞋垫增加约37.55%的足底接触面积,跖骨区和足跟区的压力峰值分别降低15.07%、36.96%,足跟处软组织内部应力降低20.83%,足底筋膜张力降低约60%。结论 所提出的方法可用于设计定制鞋垫,设计的个性化鞋垫具有更大的接触面积和降低糖尿病足底溃疡的良好潜力。     

一种外骨骼式手功能康复训练器的研究

基于正常人手指结构与运动仿生原理,对人体手部生物学特性进行分析,设计了一种可用于脑卒中或创伤后手功能康复治疗的外骨骼式手功能康复训练器。该训练器包括外骨骼机械结构和肌电控制系统,具有可适应不同人手指长度的调节机构,通过采集使用者前臂肌电对外骨骼机构的运动状态进行控制,从而驱动使用者的手指进行屈曲/伸展康复训练。最后通过机构仿真实验和实验样机实验验证了训练器的机械结构仿生性、力学性能和训练效果。     

足踝步态模拟机动力学特性仿真及实验验证

目的 研究足踝步态模拟机动力学特性,仿真着地相中的足底垂直、前后、水平3个足底反力,并在实验台中验证。方法 运用设计的5自由度步态模拟机,建立Adams虚拟样机和足踝模型（包含足部主要韧带和跖腱膜、足底软组织及跟腱力）,对其进行动力学仿真,并把仿真中的控制规律运用到实验台验证;将仿真和实验中测力板测得的足底反力与仿真和真实数据比较。结果 着地相进程中3个方向的足底反力与实际步态中吻合度较高,足部的韧带和跖腱膜、跟腱和软组织等对正确的步态有重要的影响,步态实验台能够很好重复仿真特性。结论 模拟机具备仿真人体步态着地相的能力,为活体无法进行测量的实验提供临床研究平台。     

Computer simulation for the prediction of stump loading in above-knee amputees

The efficiency and accuracy of prosthetic alignment may be greatly improved with the help of a model which establishes the relationship between alignment settings and physical parameters which are closely related to amputee comfort and performance. The paper presents a mathematical model, based on equations of motion of the shank and foot, relating above-knee amputees' stump loading to alignment adjustments. Included is a numerical example, which demonstrates the use of a computer simulation, to predict the alignment setting for minimal thigh axial torque (t.a.t.). It is suggested that the use of such a simulation should precede actual change of alignment in clinical practice.     

Improving comfort of shoe sole through experiments based on CAD-FEM modeling

It was reported that next to style, comfort is the second key aspect in purchasing footwear. One of the most important components of footwear is the shoe sole, whose design is based on many factors such as foot shape/size, perceived comfort and materials. The present paper focuses on the parametric analysis of a shoe sole to improve the perceived comfort. The sensitivity of geometric and material design factors on comfort degree was investigated by combining real experimental tests and CAD-FEM simulations. The correlation between perceived comfort and physical responses, such as plantar pressures, was estimated by conducting real tests. Four different conditions were analyzed: subjects wearing three commercially available shoes and in a barefoot condition. For each condition, subjects expressed their perceived comfort score. By adopting plantar sensors, the plantar pressures were also monitored. Once given such a correlation, a parametric FEM model of the footwear was developed. In order to better simulate contact at the plantar surface, a detailed FEM model of the foot was also generated from CT scan images. Lastly, a fractional factorial design array was applied to study the sensitivity of different sets of design factors on comfort degree. The findings of this research showed that the sole thickness and its material highly influence perceived comfort. In particular, softer materials and thicker soles contribute to increasing the degree of comfort.     

基于柔性铰链的仿生外骨骼机械手设计研究

为辅助手功能障碍患者在日常生活中更好地进行手部的康复训练与活动,提出一种基于柔性铰链的仿生外骨骼机械手。首先,基于弹性力学建立直梁型与半圆弧梁型柔性铰链刚度之间的映射关系模型,通过有限元模型改进半圆弧梁型柔性铰链的刚度设计式,并利用三铰链串联式外骨骼手指有限元模型验证单铰链刚度设计式的通用性和有效性;其次,基于修正后的刚度设计式,设计基于柔性铰链的仿生外骨骼机械手,通过绳索实现屈曲运动,通过柔性铰链的储能实现伸展运动,并根据齐次坐标变换建立相关的运动学模型,研究绳驱下的运动特性;最后,对试制的原型机进行屈曲性能与抓握能力的实验验证。外骨骼手指的仿真结果表明:单铰链的刚度设计式可用于复杂机构中各铰链的刚度计算,其误差值不大于3.5%;所试制的原型机手部执行构件仅重125g,方便使用者日常携带。屈曲性能的实验结果表明:改进的刚度设计式减小了半圆弧梁型柔性铰链40%的刚度计算误差,使误差控制在5%以内,能快速获取满足弯曲条件的铰链几何尺寸。抓握能力的实验结果表明:两名健康受试者测量出外骨骼手单指能稳定输出8N的指尖力,满足日常生活所需。因此,该外骨骼机械手可提供正常的关节活动度,其轻质便携及抓握能力高的特性还能辅助手功能障碍患者进行手部康复训练与日常活动。     

下肢运动信息采集与运动仿真

目的 建立人体下肢3D模型与生物力学模型,进行运动学和动力学分析,搭建下肢控制平台为主动式下肢假肢和人体下肢助行器的控制研究提供理论依据。方法 利用VICON人体三维运动捕捉系统采集平地行走人体下肢髋、膝、踝运动信息。利用Solidworks建立人体下肢3D模型,进行下肢运动学分析。基于Matlab中Simulink的机械仿真模块（SimMechanics）建立人体下肢模型,进行动力学分析,产生运动信号。基于Quanser半实物仿真平台搭建控制模型,接收SimMechanics产生的运动控制信号,实现对双下肢运动平台的控制。结果 利用运动学分析得到各个关节的速度和加速度信号,利用动力学仿真得到各个关节的力矩信号,对建立的人体双下肢模型进行模拟仿真,通过仿真验证了模型的合理性,利用输出的信号对双下肢运动平台进行控制实现了平地行走功能。结论 建立的平台可以进行人体下肢运动学、动力学和控制方法的研究,为主动式假肢和人体下肢助行器的控制提供借鉴作用。     

用于预防和治疗骨丢失的机械振动装置

为了预防和治疗废用性骨丢失,研制一种用于人体加载的电磁驱动型机械振动装置。该装置载荷范围为0～100kg、可产生频率为1～100Hz、加速度为0～5g的正弦波振动,用于人体及实验动物的振动加载实验。在设计上,利用上位机为操作控制平台,采用电磁驱动型振动台,引入加速度传感器和位移传感器采集振动信号并反馈电磁驱动振动台的运行情况,实现对振动加速度和振动频率的实时监测和精确控制。经实验验证,该装置适用于中、长期空间飞行中航天员骨骼系统的健康维护,以及地面各种废退性骨质疏松人群疾病的预防和治疗。     

Adaptive technique for estimating the parameters of a nonlinear mathematical lung model

In the paper, a design is presented for a lung-parameter tracking algorithm based on a nonlinear mathematical lung model for estimating the parameters of the respiratory system. The parameters are elastance of the lung and chest wall, and resistance of airways and lung tissues. A simple 2-parameter linear mathematical model describing the mechanics of the respiratory system has been found to be satisfactory only at low flow rates; since, at high flow rates, the use of this mathematical model can lead to incorrect estimates. A nonlinear term has been added to the model to account for turbulent flow, especially in the larynx and trachea. Digital simulation measuring the parameters of the nonlinear model, are presented. Inital clinical results show the feasibility of this algorithm as a method for continuous monitoring of the parameters of the respiratory system.     

Finite element modeling of a 3D coupled foot-boot model

Increasingly, musculoskeletal models of the human body are used as powerful tools to study biological structures. The lower limb, and in particular the foot, is of interest because it is the primary physical interaction between the body and the environment during locomotion. The goal of this paper is to adopt the finite element (FE) modeling and analysis approaches to create a state-of-the-art 3D coupled foot–boot model for future studies on biomechanical investigation of stress injury mechanism, foot wear design and parachute landing fall simulation. In the modeling process, the foot–ankle model with lower leg was developed based on Computed Tomography (CT) images using ScanIP, Surfacer and ANSYS. Then, the boot was represented by assembling the FE models of upper, insole, midsole and outsole built based on the FE model of the foot–ankle, and finally the coupled foot–boot model was generated by putting together the models of the lower limb and boot. In this study, the FE model of foot and ankle was validated during balance standing. There was a good agreement in the overall patterns of predicted and measured plantar pressure distribution published in literature. The coupled foot–boot model will be fully validated in the subsequent works under both static and dynamic loading conditions for further studies on injuries investigation in military and sports, foot wear design and characteristics of parachute landing impact in military.     

Whole body vibration training reduces plantar foot sensitivity but improves balance control of healthy subjects

The goal of this study was to investigate the effects of short-time whole body vibration (WBV) training on foot vibration sensitivity of healthy subjects. Furthermore, the effects of WBV on a balance task (one-leg stand) were also evaluated. 30 young healthy subjects participated in the study. Vibration perception thresholds and balance were measured prior and after a single session of a 4-min WBV training (27 Hz, 2 mm horizontal amplitude). Thresholds were measured at 200 Hz at three anatomical locations of the plantar foot area (first and fifth metatarsal heads and heel). Body balance was quantified using the length as well as the area described by the center of pressure (COP) at quiet, one-leg standing. Whereas vibration thresholds significantly increased after WBV training at all measured locations, there was a significant decrease in the balance related parameters after WBV exercise. The results indicate that the above-threshold, sinusoidal vibration used during WBV training is not an adequate strategy to stimulate/improve vibration sensitivity. The improvements seen in balance after WBV are likely to have neuromuscular mechanisms as their main component rather than increased foot sensitivity.