双足机器人足底压力测量传感系统的研究

研制了一款用于测量双足机器人足底压力中心位置和足底力有无的足底压力测量传感系统,该系统通过测力台验证了其检测结果的有效性,并利用传感系统,通过实验进行了身体速度计算和足着地检测的实验。     

基于二次特征提取与SVM的异常步态识别

长期以异常步态行走将导致人体足部、踝关节、大腿疼痛乃至身体骨骼疾病.针对目前普遍采用的基于计算机视觉的步态识别技术对数据采集环境要求严苛、视频图像分析受环境影响较大等问题,基于人行走时的足底压力变化特征进行步态识别,足底压力数据经由穿戴式步态采集器,可以不受环境限制且能实现较远距离的步态识别.并提出一种基于二次特征提取与支持先向量机的异常步态识别方法.该方法采用主成分分析法对从足底压力变化曲线中提取出来的步态特征进行二次提取.获取包含样本数据信息的主要特征信息,通过多分类支持向量机模型对步态进行识别.实验结果表明:该方法对异常步态的平均识别率达到92.625 5%,具有较高的识别精度.     

一种可穿戴型下肢助力机器人足底压力信息采集系统

为了实现可穿戴型下肢助力机器人行走过程中的步态识别,需要快速且稳定地获取足底压力数据信息。针对可穿戴型下肢助力机器人感知系统灵敏性能差、响应迟缓等缺点,结合实际应用,设计了一种系统结构更加简单优化,能够实时监测足底数据的信息采集与处理系统。该系统由足底信息采集模块与信号处理模块两部分组成,通过无线传输,可以实时监测和反馈人体行走过程中足底压力分布信息。实验结果表明,系统测试的数据符合人体行走运动中足底压力变化的规律,所设计的采集系统可以实时监测人体足底压力的信息,满足信息采集要求,为后续的控制算法验证提供有效数据。     

旋翼传感信号采集系统的指标评价体系构建研究

直升机旋翼地面试验完成旋翼传感信号的采集与处理,而旋翼传感信号的采集系统特性直接影响采集信号质量和气动特性分析准确性。经传感信号预处理后,针对旋翼传感信号采集系统性能评价问题和影响因素,给出参数指标定义及分析方法,建立传感信号采集系统的综合能力指标评价体系,研究采集系统增益精度、误差限、相位通道匹配、无杂散动态范围等指标与传感信号特征的关系,并在旋翼风洞地面试验基础上完成风压信号采集与指标评价体系验证。结果表明,传感信号采集增益精度达到0.01%,相位通道误差为0.01%,无杂散动态范围为75dBc,误差限为0.033%,线性度为0.0448%,表面压力信号误差小于0.0155%。该指标评价体系优于传统评价方式,能够全面地、准确的从静态与动态角度完成对多通道采集系统的指标评价,使采集的旋翼传感信号质量满足旋翼压力信号采集与处理要求。     

下肢假肢穿戴者跑动步态识别与膝关节控制策略研究

为研究假肢穿戴者跑动状态以及假肢膝关节的跑动控制,首先通过人体多源运动信息采集,获取髋、膝关节加速度信号、大腿股直肌部位肌电信号和足底压力信号,使用切比雪夫I型滤波方法进行降噪并提取信号特征。利用相关性分析方法,结合足底压力信号实现对跑动状态识别。在此基础上,利用粒子群优化的支持向量机方法进行信号分析,实现对6个跑动相位的识别。以四连杆假肢为被控对象,以人体跑动信号的特征点为各相位的转移条件,提出了基于有限状态机的假肢跑动控制策略。通过多项式拟合,建立了假肢膝关节控制模型,并进行了下肢假肢测试平台的验证。测试结果表明,所提方法可以实现跑动步态与相位的有效识别,并控制假肢膝关节做出正确的跑动动作。     

基于PVDF的足底测力系统研究

为实现人体不同路况运动过程中的步态识别,研制出一种便于穿戴的鞋垫式足底测力系统。以PVDF压电薄膜为传感材料,设计足底传感器。采用由电荷放大电路、滤波电路及电压放大电路组成的信号系统对传感器输出信号进行采样及处理,进行了电荷放大电路中的反馈电阻与反馈电容的实验测试选型分析研究。进行了平地行走、楼梯行走及斜坡行走的实验,实验表明,该足底测力系统具有良好的灵敏度与测量精度,并且采用PVDF内嵌在鞋垫的结构,使得测力系统适用于不同模式行走运动的检测。     

脚踏式下肢康复机器人足底力检测方法及装置

足底压力是患者进行康复训练时非常重要的生物力学参数。针对脚踏式下肢康复机器人,提出了一种新的基于弹性梁应变检测足底压力的方法,并设计了检测装置。通过分析人体足底力分布,选取足部四个主要受力点作为测量点;利用有限元仿真分析确定力与弹性梁应变的关系,建立了计算足底压力的数学模型;仿真与计算结果的对比,表明该方法及装置可实现对足底信息中重要的足底力大小的精确检测。利用该方法及装置可得到患者在训练过程中足底压力分布情况,可以用来康复评定,检测痉挛等,具有重要的临床意义。     

基于易损性分析的特种设备结构体系研究

为了解决设备结构健康监测中传感元件大量布设所带来的经费成本增加、海量数据处理复杂、维护保养不便等问题。根据易损性分析在特种设备结构健康监测中的作用,提出对结构模型融合采用重要性系数和冗余度、失效模式和路径、应变能和流动势等计算分析方法,研究设备结构体系中的最易损区域或最薄弱环节,最终确定并形成传感系统区域分布的最优布设。结果表明：在传感系统区域分布最优布设理念下,提供了一套以易损性分析为基础的计算、分析、判定的评估体系,可进一步完善设备结构健康监测技术,为后续的工程设计提供一定的理论依据和实践指导。     

同面多电极电容传感器的仿真与试验研究

针对非金属材料表面下异常或损伤的检测,提出一个同面8电极电容传感器。采用二维有限元法对该传感器的电势分布、灵敏度分布、电容测量及材料内部发生异常改变时的电容变化进行了仿真计算,用一种工程塑料作为样本,对同面多电级电容传感器用于检测非金属材料表面下的损伤或异常的可行性和有效性进行了试验研究。用主元分析方法对仿真计算的电容值和实测的电容值进行了异常识别,主元分析方法能很好地识别出非金属材料表面下的异常或损伤。仿真和初步的试验结果表明,当非金属材料表面下发生异常变化或损伤时,与材料的健康状态相比,测得的电容值减小了;用同面多电极电容传感器能有效的检测出非金属材料表面下的异常或损伤,该方法可用于实际的非金属材料表面下异常检测和健康状态监测。     

基于多维特征提取的紫外局放分级方法及应用

针对局部放电状态无法准确量化分级问题,对采用基于粒子群优化的支持向量机的状态分级方法进行了研究,通过该方法首先完成了多类特征空间在SVM核函数中的映射分类,再利用粒子群选取了最优核参数及惩罚参数。并提出了一种搭载该分级方法的便携式紫外传感电力巡检系统,结合其自身的测距功能,可向终端上位机回传紫外光斑面积、脉冲波形,测量距离、测量角度4种特征量,并以此作为分级判据,以充分利用紫外信号可靠且灵敏的特点。上位机根据已由试验数据建立起的优化分级模型,对设备的异常放电进行了诊断分级。研究结果表明,精度较传统支持向量机显著提高,避免了人为选取参数的盲目性,能够根据现场回传数据准确、实时地完成设备异常放电状态分级。     

Design and development of Fiber Bragg Grating sensing plate for plantar strain measurement and postural stability analysis

This paper describes an ab initio design and development of a novel Fiber Bragg Grating (FBG) sensor based strain sensing plate for the measurement of plantar strain distribution in human foot. The primary aim of this work is to study the feasibility of usage of FBG sensors in the measurement of plantar strain in the foot; in particular, to spatially resolve the strain distribution in the foot at different regions such as fore-foot, mid-foot and hind-foot. This study also provides a method to quantify and compare relative postural stability of different subjects under test; in addition, traditional accelerometers have been used to record the movements of center of gravity (second lumbar vertebra) of the subject and the results obtained have been compared against the outcome of the postural stability studies undertaken using the developed FBG plantar strain sensing plate.     

A lumped-parameter model to investigate the effect of plantar pressure on arterial blood flow in a diabetic foot

This paper presents a lumped-parameter model for the big-toe region that investigates the effect of plantar pressure on the diameter of the blood vessels, specifically the arteries, in the presence of arterial and/or tissue changes. The model developed in this paper uses a multi-domain energy system approach to develop the lumped-parameter differential equations. Blood flow is modelled as fluidic flow through compliant pipes that have inertia, stiffness, and damping. The tissue material is treated as a soft compliant material that transmits the external force to the blood vessels. Conclusions have been drawn to show the effect of plantar pressure, tissue damage, and their combination on the diameter of the blood vessels. The principles used here can be used to model the entire foot and the model used to investigate the effect of plantar pressure, tissue damage, and arterial changes on different parts of the foot. The work presented here may also have applications in other vascular diseases.     

动态光散射颗粒分布软测量

考虑传统动态光散射颗粒粒度分布测量用的反演算法复杂、精度不够、抗噪能力差,本文基于大数据思想,提出了一种动态光散射颗粒分布软测量方法。该方法通过调节颗粒粒度分布形状参数获得大量自相关函数及其对应颗粒分布的数据;使用这些数据对子学习机进行训练。最后,针对训练数据维数较高的特点对传统Bagging算法进行改进,并利用改进的Bagging集成算法集成子学习机以提高软测量模型的精度及泛化能力。通过模拟单峰数据和对300nm标准粒径进行软测量开展了验证实验。结果表明,该方法能够较好地测量出不同动态光散射颗粒分布的峰值及分布宽度,模拟单峰数据测量峰值精度可达1nm,300nm和503nm,标准粒径测量精度分别可达3nm和4nm,优于一般的反演算法。该软测量方法为动态光散射颗粒分布测量开辟了新的途径。     

基于计算机视觉的脚型参数测量系统的设计与实现

提出一种便捷的足部参数测量方法,仪器装置成本低廉、操作简洁。该系统利用足底扫描设备扫描足底图像,通过CMOS摄像头获取照射在足面上的结构光图片,运用图像处理技术将足面轮廓点云与足底轮廓点云叠加融合,重构足部三维形状,并据此计算脚型测量的关键特征参数。实验表明,系统能够快速精确地完成三维脚型恢复和足部特征参数的提取,具有很好的鲁棒性。     

Response Time of a Pressure Measurement System with a Connecting Tube

Abstract

A connecting tube between the measured object and the pressure sensing element is a common component part of pressure measurement systems. Dynamic characteristics of the resulting fluid oscillator may significantly influence the magnitudes of dynamic measurement errors. This paper presents an experimental analysis of dynamic characteristics of connecting tubes of different lengths and diameters. Inlet step pressure changes were generated by a system of two loudspeakers, and pressure responses were measured by a piezoelectric measurement system. Using the measured responses, the characteristic natural frequencies and damping of the system under discussion were determined. The results were further employed to estimate the response settling time, which is required to sufficiently reduce dynamic measurement errors.     

Effect of foot sole hardness, thickness and footwear on foot pressure distribution parameters in diabetic neuropathy

This paper presents details of the study undertaken to find the effects of foot sole hardness, thickness and footwear on walking-foot pressure distribution parameters (power ratio (PR)) in diabetic neuropathy. The foot sole hardness is characterized by Shore level. PR represents the ratio of high-frequency power to the total power in the power spectrum of the walking-foot pressure image distribution obtained from the optical pedobarograph. Spatial frequency distributions in the walking-foot pressure images were analysed to calculate the PR in each of the foot sole areas at different levels of foot sole sensation loss and mechanical and geometrical properties. The results show that the increase in PR in the upper foot sole Shore ranges (30-40) is 1.2-2.5 times the corresponding increase in lower Shore ranges (20-30) for some foot sole areas, implying a higher possibility of development of plantar ulcers when combined with deterioration of foot sole sensation. Plantar ulcers are found in feet with foot sole Shore values of 30, a sensation level of 45 mN and PR of 35; for Shore values of 40, sensation levels of 100 mN, with PR 52; and for Shore values above 40, sensation level > 100 mN with PR 58. Providing microcellular rubber insole footwear based on optimum hardness and thickness was found to be helpful in healing plantar ulcers in three to four weeks. Wearing preventive footwear for six months reduced hardness of the foot sole and PR values to near-normal values.     

一种新型PZT压薄膜应力传感器的设计仿真

针对目前应力传感器不能兼顾柔性、动态测量及无法测量曲面接触应力特征信息等难题,设计了一种新型的PZT压电薄膜柔性应力传感器。主要有由PZT压电薄膜、导线、特殊的压敏涂层等构成。传感器的受力信息可以通过检测PZT压电薄膜传感器的电荷变化来获取,可应用于测量各种接触面之间的应力。为研究测量轮胎路面等具有复杂曲面接触结构的应力分布提供了新的思路和方法,分析了压电传式感器的工作原理,压电薄膜的传感特性,建立有限元分析模型,进行仿真分析,结果表明该传感器结构简单、体积小,相对于传统测量方法更加可靠,适用于曲面应力的测量。     

Development of a low cost portable pressure measurement system using for garment design

Pressure comfort is an important part of garment comfort evaluation, in this paper, a low cost portable pressure measurement system (PPMS) are developed for measuring pressure distribution on garment. Three sets of different size knitted garments are fabricated for investigating the pressure distribution on a mannequin and on young female volunteers. Experimental results show curvature radius of points on the mannequin are smaller, pressures are larger which is consistent with the pressure calculation equation. Pressure distribution state on human body is different from that on mannequin due to size and shape difference even if the same garments were utilized. Dynamic pressure measurement on human body shows the pressure variations on points of human body. However, the static and dynamic pressure data can be utilized for improving quality of garments and helping design of garments.     

Association of limited joint mobility and increased plantar hardness in diabetic foot ulceration in north Asian Indian: a preliminary study

The aim of this article is to investigate the association of limited joint mobility and foot sole hardness in north Asian Indian type 2 diabetic patients. Limited joint mobility and hardness of the foot sole were measured for 39 subjects attending the AIIMS Endocrinology & Metabolism Clinic. The total subject divided into three groups: 13 control subjects (nondiabetic), 13 diabetic patients without neuropathy and 13 diabetic neuropathy patients. Neuropathy status was assessed using 10 gm Semen's Weinstein monofilament. Joint mobility parameters, such as ankle dorsiflexion/plantar flexion and metatarsophalangeal-1 dorsiflexion/plantar flexion, are measured using a goniometer. Foot sole hardness was measured using a durometer or shore meter. We found that diabetic patients with a neuropathic foot had significantly reduced joint mobility and increased foot sole hardness, placing them at risk for subsequent ulceration. Metatarsophalangeal-1 dorsiflexion/plantar flexion of both feet of diabetic patients had significant correlation (at p < 0.05, p < 0.001, p < 0.001 level) over age and body mass index. Also ankle plantar flexion/dorsiflexion and metatarsophalangeal-1 dorsiflexion/plantar flexion has a significant correlations (at p < 0.01, p < 0.05, p < 0.001, p < 0.001 level) with foot sole hardness in both feet of diabetic neuropathy subjects. Also linear regression analysis showed that duration of diabetes was significantly associated with the joint mobility parameters. In this study we conclude that joint mobility had reduced further if neuropathy and increased foot sole hardness coexisted owing to high plantar pressures. Hence, both limited joint mobility and increased foot sole hardness appears to be important determinants of foot sole ulceration in diabetic neuropathic subject.     

基于足端位置的六足机器人漫游地形感知与表征

未知复杂地形的精准感知与量化表征长期制约着六足机器人运动性能与作业效能的本质提升。针对传统基于外部传感的地形感知与表征方法普遍存在的感知范围局限、感知精度不足、表征效果欠佳等突出问题,研究借鉴足式生物地形感知机理,充分利用足端与地形交替离散接触特性,创新提出基于足端位置的六足机器人漫游地形感知与表征方法。通过构建时变机体坐标系下足端位置解算模型,解决漫游地形无序足端序列坐标高效求取难题。基于足端序列的周期化处理与矢量化描述,建立基于周期足端位置状态的局部地形量化表征方法,间接构建时变机体位姿与局部地形间周期映射关系。系统分析相邻周期机体位姿间耦合约束与变换机制,建立基于机体位姿变换的全局形貌拓扑重构方法,以连续精准机体位姿作为参照实现周期映射局部地形的拓扑拼接。样机实验结果表明,基于足端位置的六足机器人地形感知与表征方法相比传统方法能够在无需增设外部观测传感器件条件下较为精准合理的量化表征不同特征局部地形,并实现漫游地形全局形貌的精准拓扑重构。