建立基于广义Hamilton及Lie群理论的人体骨肌系统动力学方程

目的　建立一种基于广义Arial及Arial群理论的人体骨肌系统动力学建模方法。方法　首先,定义了人体骨肌系统的广义坐标,建立了人体骨肌系统Arial群位形流形;其次,在广义Arial动力学体系下建立了人体骨肌系统的动力学模型;最后,研究了该动力学模型的计算方法。结果　给出了基于广义Arial及其群理论的人体骨肌系统动力学方程,并以一个举重动作为例进行了骨肌系统动力学算法分析。结论　所提出的人体骨肌系统动力学方程能够有效真实地对人体骨肌系统进行动力学描述,为人体骨肌系统动力学分析提供了一种新方法。     

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。     

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。     

中国力学虚拟人

“中国力学虚拟人”是国家自然科学基金重点项目。它是一个人体骨肌系统参数化几何模型,通过输入人体参数,可以转换为具体研究对象的骨肌系统模型;通过运动捕捉系统,可以将测量得到的人体运动转换为骨肌系统模型的运动;通过运动、动力学分析和肌肉力计算,可以得到一个行为过程中的关节力和肌肉力;它同时是人体全身骨肌系统的有限元模型,可以做全身骨骼或局部骨骼的有限元分析。该项目将开发一个大型软件,支撑上述计算工作。它将在医学、医疗器械设计、人机工程学、体育与艺术科学、人身事故分析等广泛领域获得应用。骨肌系统建模的基本参数取自中国可视化人的研究成果。     

椭圆交叉训练机锻炼时人体生物力学与动力学特点

目的 分析椭圆交叉训练机锻炼过程中人体生物力学与动力学特性。方法 通过三维建模软件建立一种椭圆交叉训练机模型，在AnyBody软件中建立人体骨肌模型，然后将人体骨肌模型与椭圆交叉训练机模型进行耦合仿真。结果 在椭圆交叉训练机锻炼过程中，躯干部位中腰椎L5受作用力最大达到1.023 kN，腹外斜肌和腹内斜肌激活程度最大分别为80%和40%。下肢肌群中肌肉最大激活程度均未超过40%，且地面给予足底的最大反作用力为600 N。结论 人体使用椭圆交叉训练机进行锻炼可以缓解慢性腰痛患者疼痛，有助于提高脑卒中偏瘫患者躯干控制能力及平衡功能。对比跑步锻炼，使用椭圆机交叉训练机锻炼能起到保护人体膝关节的作用。     

基于二次规划的人体屈伸运动肌肉力预测研究

目的研究人体屈伸运动过程中的肌肉力。方法在"中国力学虚拟人"模型的基础上,确定屈伸运动中参与运动肌肉束的生理横截面积及附着点的起止位置,建立完整的人体胸腰部骨肌系统模型。利用NDI运动捕捉系统获取脊柱形状的变化,利用肌电测量系统采集运动中肌肉的肌电信号规律。采用二次规划方法对不同运动速度和不同负载下的肌肉力进行优化预测。结果通过二次规划法预测出的肌肉力与肌电信号具有较好的一致性。结论该方法可以有效地预测人体屈伸运动中的肌肉力,对深入了解肌肉的运动机理,预防和减少运动损伤发生具有重要意义。     

人服系统上肢交互生物力学仿真模型

目的 通过建立人-舱外服上肢交互生物力学仿真模型计算穿着舱外服后航天员上肢关节力矩和肌肉力,满足出舱活动风险评估的需求。方法 分别建立舱外服手臂的刚体运动学模型和关节阻尼力矩迟滞模型以描述舱外服关节的运动和力学特性。通过对舱外航天服肘部和人体肘部位置进行约束实现人体和舱外服手臂之间的运动学耦合,利用虚拟反作用力元实现两者之间的动力学耦合,在反向运动生物力学架构下建立一体化仿真模型。利用该模型对宇航员穿着加压、未加压舱外服和不穿着舱外服3种工况下肘弯曲/伸展进行仿真案例分析。结果 3种工况下肱二头肌的预测肌肉激活和积分肌电的相关性分别为0.86、0.71、0.65,肱三头肌对应的相关性分别为0.75、0.61、0.60,采用预测肌肉激活和积分肌电的一致性定性验证了模型的正确性,利用舱外服肘关节阻尼力矩与人体肘关节肌肉承受力矩之间的一致性验证了模型的合理性。结论 该人服系统上肢交互生物力学仿真模型能有效计算航天员穿着舱外服后的上肢关节力矩和肌肉力,且仿真结果和实验表明,加压后舱外服关节阻尼力矩造成较大的人体关节力矩和肌肉负荷,为航天员出舱活动中的体力负荷和骨肌风险评估提供方法学支撑。     

太极拳运动下肢生物力学研究进展

太极拳的保健和康复功能已经在全球得到认可,国内外的专家学者利用运动生物力学方法对太极拳保健作用的机制进行研究,其中大部分是针对人体下肢的研究。检索2007~2015年太极拳运动的下肢生物力学研究文献20篇(15篇英文和5篇中文),根据研究目的和评价指标,从太极拳本身的运动学和动力学特点及其对下肢的影响、太极拳对下肢肌肉活动的影响、太极拳运动对人体下肢生物力学参数与其他系统参数相互作用的影响三个方面进行综述,并对太极拳运动下肢生物力学研究的展望和不足之处进行总结。     

人服系统上肢交互生物力学仿真模型

目的通过建立人-舱外服上肢交互生物力学仿真模型计算穿着舱外服后航天员上肢关节力矩和肌肉力,满足出舱活动风险评估的需求。方法分别建立舱外服手臂的刚体运动学模型和关节阻尼力矩迟滞模型以描述舱外服关节的运动和力学特性。通过对舱外航天服肘部和人体肘部位置进行约束实现人体和舱外服手臂之间的运动学耦合,利用虚拟反作用力元实现两者之间的动力学耦合,在反向运动生物力学架构下建立一体化仿真模型。利用该模型对宇航员穿着加压、未加压舱外服和不穿着舱外服3种工况下肘弯曲/伸展进行仿真案例分析。结果3种工况下肱二头肌的预测肌肉激活和积分肌电的相关性分别为0.86、0.71、0.65,肱三头肌对应的相关性分别为0.75、0.61、0.60,采用预测肌肉激活和积分肌电的一致性定性验证了模型的正确性,利用舱外服肘关节阻尼力矩与人体肘关节肌肉承受力矩之间的一致性验证了模型的合理性。结论该人服系统上肢交互生物力学仿真模型能有效计算航天员穿着舱外服后的上肢关节力矩和肌肉力,且仿真结果和实验表明,加压后舱外服关节阻尼力矩造成较大的人体关节力矩和肌肉负荷,为航天员出舱活动中的体力负荷和骨肌风险评估提供方法学支撑。     

人服系统上肢交互生物力学仿真模型

目的 通过建立人-舱外服上肢交互生物力学仿真模型计算穿着舱外服后航天员上肢关节力矩和肌肉力，满足出舱活动风险评估的需求。方法 分别建立舱外服手臂的刚体运动学模型和关节阻尼力矩迟滞模型以描述舱外服关节的运动和力学特性。通过对舱外航天服肘部和人体肘部位置进行约束实现人体和舱外服手臂之间的运动学耦合，利用虚拟反作用力元实现两者之间的动力学耦合，在反向运动生物力学架构下建立一体化仿真模型。利用该模型对宇航员穿着加压、未加压舱外服和不穿着舱外服3种工况下肘弯曲/伸展进行仿真案例分析。结果 3种工况下肱二头肌的预测肌肉激活和积分肌电的相关性分别为0.86、0.71、0.65，肱三头肌对应的相关性分别为0.75、0.61、0.60，采用预测肌肉激活和积分肌电的一致性定性验证了模型的正确性，利用舱外服肘关节阻尼力矩与人体肘关节肌肉承受力矩之间的一致性验证了模型的合理性。结论 该人服系统上肢交互生物力学仿真模型能有效计算航天员穿着舱外服后的上肢关节力矩和肌肉力，且仿真结果和实验表明，加压后舱外服关节阻尼力矩造成较大的人体关节力矩和肌肉负荷，为航天员出舱活动中的体力负荷和骨肌风险评估提供方法学支撑。     

Integrating modelling and experiments to assess dynamic musculoskeletal function in humans

Magnetic resonance imaging, bi-plane X-ray fluoroscopy and biomechanical modelling are enabling technologies for the non-invasive evaluation of muscle, ligament and joint function during dynamic activity. This paper reviews these various technologies in the context of their application to the study of human movement. We describe how three-dimensional, subject-specific computer models of the muscles, ligaments, cartilage and bones can be developed from high-resolution magnetic resonance images; how X-ray fluoroscopy can be used to measure the relative movements of the bones at a joint in three dimensions with submillimetre accuracy; how complex 3-D dynamic simulations of movement can be performed using new computational methods based on non-linear control theory; and how musculoskeletal forces derived from such simulations can be used as inputs to elaborate finite-element models of a joint to calculate contact stress distributions on a subject-specific basis. A hierarchical modelling approach is highlighted that links rigid-body models of limb segments with detailed finite-element models of the joints. A framework is proposed that integrates subject-specific musculoskeletal computer models with highly accurate in vivo experimental data.     

头部前屈运动过程中颈肌特性的研究

目的分析人体头部前屈运动过程中头颈部肌群活动特性,探索人体头颈部肌肉疲劳原因。方法基于AnyBody软件建立人体头颈部肌骨模型,以Vicon运动捕捉系统测量数据为输入,对头部前屈运动过程中的肌力进行仿真,并结合文献数据进行分析。结果颈后肌群在头部前屈运动中起主要作用。在头部前屈45%和75%行程位置肌力分配模式不同。肌力对前屈角位移的积分WM一定程度上反映了肌肉的疲劳特性,其中颈半棘肌和多裂肌在头部前屈运动过程中WM最大,容易出现疲劳。结论本文建立的头颈部肌骨模型可为分析人体运动状态下肌肉分析提供技术平台。     

Effect of Subject-Specific Vertebral Position and Head and Neck Size on Calculation of Spine Musculoskeletal Moments

Spine musculoskeletal models used to estimate loads and displacements require many simplifying assumptions. We examined how assumptions about subject size and vertebral positions can affect the model outcomes. Head and neck models were developed to represent 30 subjects (15 males and 15 females) in neutral posture and in forward head postures adopted while using tablet computers. We examined the effects of (1) subject size-specific parameters for head mass and muscle strength; and (2) vertebral positions obtained either directly from X-ray or estimated from photographs. The outcome metrics were maximum neck extensor muscle moment, gravitational moment of the head, and gravitational demand, the ratio between gravitational moment and maximum muscle moment. The estimates of maximum muscle moment, gravitational moment and gravitational demand were significantly different when models included subject-specific vertebral positions. Outcome metrics of models that included subject-specific head and neck size were not significantly different from generic models on average, but they had significant sex differences. This work suggests that developing models from X-rays rather than photographs has a large effect on model predictions. Moreover, size-specific model parameters may be important to evaluate sex differences in neck musculoskeletal disorders.     

Component mode synthesis approach to estimate tibial strains in gait

This paper presents a component mode synthesis approach to estimate tibial strains in gait. First, 3D models of the human musculoskeletal system were constructed based on the China Visible Human (CVH) dataset. Then an experiment was carried out to capture the subject gait motion. An inverse dynamic algorithm was developed to predict joint moments and an optimization algorithm was used to predict muscle forces in subject gait. Finally, a finite element model of the tibia was built. The muscle forces were input into the tibia finite element model as boundary conditions. Through the proposed component mode synthesis approach, 12 mode shapes and strains of tibia were estimated. The maximum and minimum principal strain magnitudes of tibia are 499 microstrain and ?612 microstrain respectively. The maximum and minimum strain rates of tibia are 4130 microstrain s^?1 and –3970 microstrain s^?1 respectively. These figures are in line with literature values from in vivo measurements using an invasive strain gauge. In conclusion, the component mode synthesis approach may be used as a surrogate for experimental bone strain measurements and thus be of use in detailed strain estimation of bones in different applications.     

A Probabilistic Model of Glenohumeral External Rotation Strength for Healthy Normals and Rotator Cuff Tear Cases

The reigning paradigm of musculoskeletal modeling is to construct deterministic models from parameters of an “average” subject and make predictions for muscle forces and joint torques with this model. This approach is limited because it does not perform well for outliers, and it does not model the effects of population parameter variability. The purpose of this study was to simulate variability in musculoskeletal parameters on glenohumeral external rotation strength in healthy normals, and in rotator cuff tear case using a Monte Carlo model. The goal was to determine if variability in musculoskeletal parameters could quantifiably explain variability in glenohumeral external rotation strength. Multivariate Gamma distributions for musculoskeletal architecture and moment arm were constructed from empirical data. Gamma distributions of measured joint strength were constructed. Parameters were sampled from the distributions and input to the model to predict muscle forces and joint torques. The model predicted measured joint torques for healthy normals, subjects with supraspinatus tears, and subjects with infraspinatus–supraspinatus tears with small error. Muscle forces for the three conditions were predicted and compared. Variability in measured torques can be explained by differences in parameter variability.     

全膝关节置换个体化患者右转步态的骨肌多体动力学仿真

目的构建个体化患者全膝关节置换(total knee replacement,TKR)的骨肌多体力学模型,模拟患者下肢右转步态时体内膝关节的生物力学行为。方法以1位具体患者的相关数据为材料,基于骨肌动力学仿真软件Any Body及其依赖于力的运动学建模方法,建立与患者相对应的TKR下肢骨肌多体动力学模型,并对患者的右转步态进行模拟。通过逆动力学分析右转步态,同时预测患者膝关节接触力、关节运动、肌肉活性和韧带力。结果模型预测的胫骨-股骨关节内、外侧接触力的均值均方根误差分别为285、164 N,相关系数分别为0.95和0.61,预测的髌骨接触力均值最大值为250 N。模型预测的接触力和肌肉活性与患者实验测量结果基本一致。此外,模型预测的胫骨-股骨的伸展弯曲、内外旋和内外翻运动的均值分布范围分别为3°~47°、-3.4°~1.5°、0.2°~-1.5°,胫骨-股骨的前后、上下和内外侧平移的运动范围分别为2.6~9.0 mm、1.6~3.2 mm、4.2~5.2 mm。模型还预测了内、外侧旁系韧带力和后交叉韧带力,其最大值分别为190、108、108 N。结论所开发的模型能够预测人工膝关节体内生物力学行为,为后续研究膝关节假体临床失效问题提供强有力的计算平台。     

基于骨肌模型的肌肉力计算方法及其面临的若干问题

肌肉力计算已经成为骨肌损伤防护、关节假体设计等研究的重要组成部分,目前基于骨肌系统模型的肌肉力计算方法有:静态优化、动态优化以及基于力-肌电关系的肌肉力计算。本文分析了肌肉力计算方法和骨肌系统建模的研究现状以及面临的若干问题。个性化建模、计算方法的改进和计算结果的实验验证将是今后的研究重点。     

基于肌肉机械功的异常步态分析

目的通过量化背屈肌和跖屈肌之间的协同作用分析不同行走速度下偏瘫受试者踝关节角度的异常,以深层次地分析患者的运动功能。方法将从肌电(electromyograph,EMG)驱动的人体肌肉骨骼模型中获得的肌力、力臂和关节角度参数进行预处理,利用肌力和力臂差计算患侧跖屈肌群和背屈肌群做功情况,以此分析由踝关节角度曲线反映出的步态异常。结果跖屈肌群(主要是比目鱼肌和腓肠肌)过度活跃做正功,保持高强度向心收缩,背屈肌群(主要是胫骨前肌)无力几乎不做功导致肌肉协同失衡,从而引起步态异常。结论本文提出的量化肌肉机械功方法可以深层次地分析肌肉之间的协同作用,对于偏瘫患者异常步态的分析具有重要的意义。     

Multibody dynamic simulation of knee contact mechanics

Multibody dynamic musculoskeletal models capable of predicting muscle forces and joint contact pressures simultaneously would be valuable for studying clinical issues related to knee joint degeneration and restoration. Current three-dimensional multibody knee models are either quasi-static with deformable contact or dynamic with rigid contact. This study proposes a computationally efficient methodology for combining multibody dynamic simulation methods with a deformable contact knee model. The methodology requires preparation of the articular surface geometry, development of efficient methods to calculate distances between contact surfaces, implementation of an efficient contact solver that accounts for the unique characteristics of human joints, and specification of an application programming interface for integration with any multibody dynamic simulation environment. The current implementation accommodates natural or artificial tibiofemoral joint models, small or large strain contact models, and linear or nonlinear material models. Applications are presented for static analysis (via dynamic simulation) of a natural knee model created from MRI and CT data and dynamic simulation of an artificial knee model produced from manufacturer's CAD data. Small and large strain natural knee static analyses required 1 min of CPU time and predicted similar contact conditions except for peak pressure, which was higher for the large strain model. Linear and nonlinear artificial knee dynamic simulations required 10 min of CPU time and predicted similar contact force and torque but different contact pressures, which were lower for the nonlinear model due to increased contact area. This methodology provides an important step toward the realization of dynamic musculoskeletal models that can predict in vivo knee joint motion and loading simultaneously.     

A feedback model reproduces muscle activity during human postural responses to support-surface translations

Although feedback models have been used to simulate body motions in human postural control, it is not known whether muscle activation patterns generated by the nervous system during postural responses can also be explained by a feedback control process. We investigated whether a simple feedback law could explain temporal patterns of muscle activation in response to support-surface translations in human subjects. Previously, we used a single-link inverted-pendulum model with a delayed feedback controller to reproduce temporal patterns of muscle activity during postural responses in cats. We scaled this model to human dimensions and determined whether it could reproduce human muscle activity during forward and backward support-surface perturbations. Through optimization, we found three feedback gains (on pendulum acceleration, velocity, and displacement) and a common time delay that allowed the model to best match measured electromyographic (EMG) signals. For each muscle and each subject, the entire time courses of EMG signals during postural responses were well reconstructed in muscles throughout the lower body and resembled the solution derived from an optimal control model. In ankle muscles, >75% of the EMG variability was accounted for by model reconstructions. Surprisingly, >67% of the EMG variability was also accounted for in knee, hip, and pelvis muscles, even though motion at these joints was minimal. Although not explicitly required by our optimization, pendulum kinematics were well matched to subject center-of-mass (CoM) kinematics. Together, these results suggest that a common set of feedback signals related to task-level control of CoM motion is used in the temporal formation of muscle activity during postural control.