人体运动膝关节咬合的协调约束条件

本文基于人膝关节的解剖特征，建立了人体下肢在矢状面运动时，膝关节咬合的运动协调约束方程这些方程对于建立人体下肢的解剖基生物动力模型是十分重要的它们包含了运动膝关节股骨与胫骨相咬合时的滚动和滑动两种运动     

一个解剖基人体下肢的生物动力模型--第一部分: 模型描述

建立一个完整的解剖基人体下肢二维（矢状面内）生物动力模型,该模型仿真了人体下肢的生物动力运动,并可用来计算人体下肢在冲击外载荷或肌肉活性力的作用下,下肢的重要承力部位－膝关节处的结构力（包括：膝关节的咬合接触力、膝关节处四个主要韧带张力等）和人体下肢的肌肉群力;同时本模型也可用来计算人体下肢在运动期间,膝关节处的咬合位移以及膝关节和髋关节的屈伸位移等。另外,模型还为研究人工关节、人工韧带和人工肌肉     

踝关节外骨骼人机耦合动力学与助力性能分析

踝关节在人体下肢运动过程中提供了最大的关节力矩, 因此在下肢增强型外骨骼的研究中, 踝关节外骨骼受到了重点关注. 穿戴外骨骼的人体的行走是典型的动力学问题, 但目前人机耦合动力学的相关研究还处于早期阶段. 本文以绳驱踝关节外骨骼为研究对象, 融合机器人正运动学方法和拉格朗日方程建立了考虑足?地交互力、人体关节力矩和外骨骼力矩的人?机耦合动力学模型. 模型中, 足?地交互力由Kelvin-Voigt模型结合库伦摩擦模型描述, 人体关节力矩由基于粒子群优化的PD控制生成, 外骨骼期望力矩由上层控制器依据人体步态周期确定. 通过基于模型的动力学仿真, 本文从人体踝关节角度、踝关节力矩、踝关节功率和踝关节做功多个角度系统分析了踝关节外骨骼对人体行走的助力效果. 研究表明, 在2.0 km/h到6.5 km/h的人体步行速度下, 穿戴外骨骼可以实现至少24.84%的人体踝关节平均力矩下降和至少24.69%的踝关节做功下降. 本文也开展了基于SCONE平台的肌肉骨骼建模和预测仿真. 仿真结果表明, 在3.6 km/h的步行速度下, 穿戴外骨骼可以有效降低比目鱼肌的激活度峰值, 并使肌电信号的RMS值下降了6.21%, 从而从生理学的角度证实了踝关节外骨骼的助力效果. 本文的结果进一步完善了人体下肢?外骨骼耦合系统的动力学建模和分析方法, 从动力学和生理学角度证实和解释了踝关节外骨骼对行走的助力机制, 也为今后下肢外骨骼的实验研究提供了理论支撑.      

一个解剖基人体下肢的生物动力模型--第二部分: 数值结果

表述人体下肢生物动力模型的数值技术、数值结果并将其与文献进行比较.模型显示:当人体下肢小腿受冲击外载荷作用时,在膝关节处所产生的4个主要韧带张力以及膝关节处的咬合接触力,在大腿固定不动(或运动受到约束)的情况下,要远大于大腿未受约束的情形.这与医学常识是吻合的.     

一个解剖基人本下肢的生物动力模型：第二部分：数值结果

表述人体下肢生物动力模型的数值技术,数值结果并将其与献进行比较,模型显示：当人体下肢小腿受冲击外载荷作用时,在膝关节处所产生的４个主要韧带张力以及膝关节处的咬合接触力,在大腿固定不动（或运动受到约束）的情况下,要远大于大腿未受约束的情况下,要远大于大腿未受约束的情形,这与医学常识是吻合的。     

跑鞋与触地模式的生物力学及其与损伤关系研究进展

现今各种性能的跑鞋逐渐发展,跑鞋科技不断进步,但跑步导致的下肢损伤率依然居高不下。无论是传统跑鞋(运动控制鞋、缓冲鞋、中性稳定鞋),还是近年来再度流行起来的极简鞋,能否降低损伤发生率、提高运动表现仍存在较大争议。本研究针对不同的跑鞋进行分类梳理,总结不同跑鞋下的生物力学模式及其对下肢损伤的影响。研究表明：根据脚型定制的传统缓冲跑鞋并不会减少损伤发生率;极简鞋具有减少关节扭矩和髌骨接触应力、强化足内在肌和跟腱力学特性等优势,建议穿着极简鞋跑步采用循序渐进的转化方式,尽量配合下肢、足踝肌群的强化练习,如足核心训练。未来的研究应着重关注跑鞋与下肢损伤的内在生物力学机制,为减小和预防下肢损伤提供理论依据,并为跑者选择适合自身的跑鞋提供更具建设性的意见。     

基于人体下肢运动学机理的行人导航方法

利用人体运动特征实现行人导航是近年来导航技术领域新兴的研究方向之一。针对惯性测量组件足部安装方式在人体较高过载的运动中无法有效实现零速修正的问题,研究了一种惯性测量组件在人体下肢分布式安装,基于人体下肢运动学机理构建虚拟足部惯性测量组件,从而实现人体导航定位的方法。阐述了行人导航系统的结构与虚拟惯性传感组件的构建机理,研制了系统原理样机。实验结果表明所提出的方法在人体较高过载的行进中可有效克服测量信息超量程、冲击等因素对导航解算的影响,定位精度约为行进距离的6%,并通过分析总结了影响该类型行人导航系统性能的各项主要因素,为进一步研究提供了一定的理论与技术基础。     

肌电测量技术和鲫鱼C形起动过程中肌电信号测量初探

鱼在水中游动时,骨骼肌在中枢神经系统的控制下进行主动收缩,将力和位移传递给鳍和皮肤等执行器官,再通过执行器官与水进行力的相互作用和能量的交换后推动鱼体自身运动.为研究鱼在不同运动过程中肌肉活动的方式与强度,本文引进肌电图测量术(EMG).将表面绝缘的不锈钢探针植入鲫鱼的红肌内,肌电信号通过自主设计制作的肌电放大器放大,由计算机记录,用以表征鲫鱼在C形起动过程中转弯一侧的红肌活动的持续时间及强度.本文着重阐述了肌电测量技术,肌电实验的手术操作过程,并通过对肌电信号的测量结果进行定量分析,得到了鲫鱼C形起动过程中转弯侧红肌基本同时开始活动,其活动时间大致相同,以及躯体前端红肌活动最为剧烈的结论.     

豚鼠内耳前庭-半规管生物力学模型研究

人体维持平衡主要依靠前庭、视觉及本体感觉3个系统的相互协调来完成,其中前庭系统最为重要.因其结构细微且位置深在,传统方法难以满足现代前庭医学定位、定性、定量的研究需要,而生物数值模拟研究方法在现代耳科学研究中优势显著.建立精准的生物数值模型是其重点之一.本研究通过连续组织切片技术获取豚鼠内耳膜性结构的二维解剖数据,进一步建立同时包括前庭和3个半规管的宏观三维生物数值模型,其空间结构特征及尺寸与解剖学观察一致;数值模拟临床医学冷热实验,量化描述了不同环境温度激励下半规管内壶腹嵴顶位移、速度和压强等参数随时间变化的生物力学特征,其与临床观察到的眼震结果一致.总之,通过连续组织切片技术获取内耳膜性结构二维解剖数据并据此建立内耳三维生物数值模型的研究方法可行,所建立的生物模型可满足前庭-半规管平衡功能定位、定性、定量的研究需要.      

跳跃运动的动力学解释

本文建立由质点与无质量刚性杆组成的人体简化模型。将动力学方程化作以位置坐标为自变量的自治形式,以膝关节肌肉力矩作为控制变量,利用以质心的速度与加速度为相坐标的相平面分析人体的跳跃运动。分析结果可对腾空高度与肌肉的输出功、爆发力、下肢起始位置及上肢辅助动作的相互关系作出定性的动力学解释。     

Multibody dynamics analysis of the human upper body for rotorcraft–pilot interaction

The study of the biodynamic response of helicopter passengers and pilots, when excited by rotorcraft vibrations that are transmitted through the seat and, for the latter, the control inceptors, is of great importance in different areas of aircraft design. Handling qualities are affected by the proneness of the aircraft to give rise to adverse interactions, an unwanted quality that can be captured by the so-called biodynamic feedthrough. On the other hand, the transmissibility of vibrations, especially from the seat to the head, affects the comfort of pilots and passengers during flight. Detailed and parametrised multibody modelling of the human upper body can provide a strong base to support design decisions justified by a first-principles approach. In this work, a multibody model of the upper body is formed by connecting a previously developed detailed model of the arms to a similarly detailed model of the spine. The whole model can be adapted to a specific subject, identified by age, gender, weight and height. The spine model and the scaling procedure have been validated using the experimental results for seat to head transmissibility. The coupled spine-arms model is used to evaluate the biodynamic response in terms of involuntary motion induced on the control inceptors, including the related nonlinearities.

     

A Recursive Formulation for Constrained Mechanical System Dynamics: Part II. Closed Loop Systems

ABSTRACT

ABSTRACT A recursive formulation of the equations of motion of constrained mechanical systems with closed loops is derived, using tools of variational and vector calculus. Kinematic couplings between pairs of contiguous bodies presented in Part 1 of this paper are generalized. Lagrange multipliers are introduced to account for the effects of joints that are cut to define a tree structure. Constraint Jacobian terms are added to the reduced variational equations derived in Part I. Cut-joint constraint acceleration equations are derived, to complete the reduced equations of motion. Lagrange multipliers associated with each cut-joint are eliminated at the first junction body encountered that permits closing the loop that constraints in cut joint. The inductive algorithm developed in Part I is used to calculate accelerations for the system. A multi-loop compressor is analyzed to illustrate use of the method.     

关于人膝关节生物力学模型的研究现状

建立人膝关节模型是生物力学研究领域中最具挑战性的课题之一．本文对人膝关节生物力学模型的研究现状予以简单的评估和综述．结果显示:目前用于研究人膝关节的大部分模型,均属静力或准静力模型;仅建立了极少的人膝关节解剖基生物动力模型,且均属二维动力模型．因此,建立一个三维真实人膝关节生物动力模型是目前迫在眉睫的工作      

Analytical study of the nonlinear behavior of a shape memory oscillator: Part II—resonance secondary

In this work, the response of a single-degree-of-freedom shape memory oscillator subjected to the excitation harmonic has been investigated. Equation of motion is formulated assuming a polynomial constitutive model to describe the restitution force of the oscillator. Here the method of multiple scales is used to obtain an approximate solution to the equations of the motion describing the modulation equations of amplitude and phase, and to investigate theoretically its stability. This work is presented in two parts. In Part I of this study we showed the modeling of the problem where the free vibration of the oscillator at low temperature is analyzed, where martensitic phase is stable. Part I also presents the investigation dynamics of the primary resonance of the pseudoelastic oscillator. Part II of the work is focused on the study in the secondary resonance of a pseudoelastic oscillator using the model developed in Part I. The analysis of the system in Part I as well as in Part II is accomplished numerically by means of phase portraits, Lyapunov exponents, power spectrum and Poincare maps. Frequency-response curves are constructed for shape memory oscillators for various excitation levels and detuning parameter. A rich class of solutions and bifurcations, including jump phenomena and saddle-node bifurcations, is found.     

Analytical study of the nonlinear behavior of a shape memory oscillator: Part I—primary resonance and free response at low temperatures

In this work, the response of a single-degree-of-freedom shape memory oscillator subjected to the excitation harmonic has been investigated. Equation of motion is formulated assuming a polynomial constitutive model to describe the restitution force of the oscillator. Here the method of multiple scales is used to obtain an approximate solution to the equations of the motion describing the modulation equations of amplitude and phase, and to investigate theoretically its stability. This work is presented in two parts. In Part I of this study we showed the modeling of the problem where the free vibration of the oscillator at low temperature is analyzed, where martensitic phase is stable. Part I also presents the investigation dynamics of the primary resonance of the pseudoelastic oscillator. Part II of the work is focused on the study in the secondary resonance of a pseudoelastic oscillator using the model developed in Part I. The analysis of the system in Part I as well as in Part II is accomplished numerically by means of phase portraits, Lyapunov exponents, power spectrum and Poincare maps. Frequency-response curves are constructed for shape memory oscillators for various excitation levels and detuning parameter. A rich class of solutions and bifurcations, including jump phenomena and saddle-node bifurcations, is found.     

Two-to-one resonant multi-modal dynamics of horizontal/inclined cables. Part I: Theoretical formulation and model validation

This paper is first of the two papers dealing with analytical investigation of resonant multi-modal dynamics due to 2:1 internal resonances in the finite-amplitude free vibrations of horizontal/inclined cables. Part I deals with theoretical formulation and validation of the general cable model. Approximate nonlinear partial differential equations of 3-D coupled motion of small sagged cables – which account for both spatio-temporal variation of nonlinear dynamic tension and system asymmetry due to inclined sagged configurations – are presented. A multi-dimensional Galerkin expansion of the solution of nonplanar/planar motion is performed, yielding a complete set of system quadratic/cubic coefficients. With the aim of parametrically studying the behavior of horizontal/inclined cables in Part II [25], a second-order asymptotic analysis under planar 2:1 resonance is accomplished by the method of multiple scales. On accounting for higher-order effects of quadratic/cubic nonlinearities, approximate closed-form solutions of nonlinear amplitudes, frequencies and dynamic configurations of resonant nonlinear normal modes reveal the dependence of cable response on resonant/nonresonant modal contributions. Depending on simplifying kinematic modeling and assigned system parameters, approximate horizontal/inclined cable models are thoroughly validated by numerically evaluating statics and non-planar/planar linear/non-linear dynamics against those of the exact model. Moreover, the modal coupling role and contribution of system longitudinal dynamics are discussed for horizontal cables, showing some meaningful effects due to kinematic condensation.     

Non-linear dynamics of curved beams. Part 2, numerical analysis and experiments

The aim of this work is to formulate a model for the study of the dynamics of curved beams undergoing large oscillations. In Part 1, the interest was oriented to the formulation of a consistent analytical model and to obtain the equations of motion in weak form. In Part 2, a case-study is considered and the response for various initial curved configurations, obtained by varying the initial curvature, is analyzed. Both the free and the forced problems are considered: the linear free dynamics are studied to detect how the initial configuration affects the modal properties and to enlighten the typical phenomena of frequency coalescence and avoidance; the forced dynamics are then studied for different internal resonance conditions to enlighten the phenomenon of the dynamic instability under a shear periodic tip follower force and to describe the various classes of post-critical motion. The results of experimental tests conducted on a slightly imperfect straight beam prototype are eventually discussed.