SOI高g值压阻式加速度传感器与工艺实现

基于SOI技术,利用电感耦合等离子体硅深加工,设计制备了一种新型平面内振动高g值压阻式加速度计.该加速度计包括X轴向与Y轴向单元,采用扇形敏感质量块平板内振动结构.对称的布局方式,有效地消除了灵敏度的交叉干扰,提高了传感器的测量精度.测试系统分析出加速度传感器的灵敏度是1.170 μV/g.研究表明该加速度传感器可实现对量程高达25×104g加速度的测量.     

基于传感器优化与鲁棒预测的等效加速度前馈

在一类仅安装MEMS加速度计和图像传感器的光电跟踪系统中,等效加速度前馈控制方法能够有效提高系统的跟踪能力.但是,加速度计低频噪声、目标合成轨迹延迟和运动模型不确定性,会对跟踪效果带来限制.因此,本文提出一种基于传感器优化与鲁棒预测的等效加速度前馈方法,来进一步提升系统的跟踪能力.使用加速度计测量值和系统加速度模型计算值进行频域融合,可以优化加速度计的低频性能;而采用鲁棒预测算法,能够减弱目标合成轨迹延迟及运动模型不确定性的影响,获得更准确的加速度前馈值.实验结果表明,该方法可以提高系统在0.1 Hz～4.5 Hz的跟踪能力.     

对称体微机械电容加速度传感器的结构设计

描述了一种用无掩各向异性腐蚀技术制造以称体微机械梁，质量块加速度传感器的结构，由于梁在质量块中心对称位置上，在结构上的消除了加速度传感器的横向灵敏度效应，在对四梁结构及悬臂梁结构加速度计灵敏度及固有频率进行分析的基础上，用灵敏度－频率积取优值的方法进行了加速计的结构参数优化，采用了一种新颖的微力微痊移天平测试方法。初步测量了加速度计结构的静态特性。     

高速气流对冲击振动加速度测试的影响

在火箭炮和导弹发射过程中,用于测试发射装置振动加速度的加速度计会受到高速气流的冲击。为了探究高速气流对加速度测试可能造成的影响,本文介绍了有关实验室及靶场测试方法与结果。在实验室内是采用压缩空气,模拟高速气流环境,观测加速度计分别在裸露与掩埋状态下的响应曲线。通过对测试曲线的比较分析,并结合靶场测试结果,得出在高速气流环境下应对加速度计进行气流防护的结论,该结论及试验方法对火箭炮和导弹发射装置的加速度测试具有一定的借鉴意义。     

加速度传感器对重力仪振动补偿效果分析北大核心CSCD

为分析加速度传感器对重力仪的补偿效果,基于NIM-3C绝对重力仪搭建了平台式重力测量实验平台,并用激光测振仪输出信号作为标准信号,通过实验标定了平台式重力测量环境下MSA1000A-02、991B、INV9832-50三种不同型号的加速度型传感器的振动采集性能。实验结果表明,为保证平台式重力测量环境下的重力测量不确定度达到mGal量级,加速度计引入的测量不确定度应在百μGal以内。在平台式重力测量工况下,传感器MSA1000A-02和激光测振仪所测振动(标准信号)的拟合二次项系数极差为2.94μGal,满足平台式重力测量环境的不确定度及带宽等的要求。     

动态测试技术的发展系列讲座

第二讲 振动冲击测量的发展、现状与未来振动与冲击测量的核心是传感器.被广泛使用的加速度传感器至今已有60年的历史.本文将对压电加速度计的发展、振动与冲击测量技术的现状、以及新一代智能加速度计和振动、冲击测量的未来进行综合评述.1 加速度传感器的发展由于加速度传感器的发明,使振动与冲击测量逐渐在工业界获得广泛应用.最早的加速度传感器于1938年在电阻应变计发明后不久就研制成功,并于1940年开始在航空和土木等工程中获得应用.电阻应变式加速度计的缺点较多:一是输出信号小(最大输出信号约30mV),信噪比低;二是灵敏度与频率范围矛盾突出;三是为了提高使用频率范围需加人工阻尼(如采用硅油阻尼,阻尼比可达临界值,从而使可用频率达到谐振频率的一半),但阻尼介质对温度敏感,且不能在高温下工作.     

无线加速度传感器在人体运动参数测量中的应用研究

针对实验室环境中的人体运动参数测量手段在户外测量中的不足,本文利用无线加速度传感器,设计了一种人体运动参数的测量方案,可以在户外方便有效地测量人体运动。利用该方案,对人体步态运动和振动环境中的人体运动进行了测量实验。实验结果证明了无线加速度传感器在人体运动参数测量中应用的可行性。     

基于双离心机的线加速度计动态校准

介绍基于双离心机的线加速度计动态校准方法,在分析双离心机原理的基础上,对各加速度分量进行合成,建立了基于双离心机的正弦加速度数学模型.阐述了线加速度计动态校准装置的组成和校准过程,分析了校准装置所产生的正弦加速度的幅值测量不确定度和相位测量不确定度.介绍了实验数据的处理方法三参数正弦波拟合算法,并在正弦加速度幅值为200 m/s.、角频率范围为0.1～10 Hz的条件下进行了实验验证,给出了相应的实验曲线图.线加速度计动态校准装置具有产生大g值正弦加速度的优点,正弦加速度幅值可达700 m/s2.     

基于加速度传感器的丝杠传动系统建模及控制研究

提出了基于加速度传感器的丝杠传动系统建模及控制策略,可以通过实验测量存在结构非刚性因素时丝杠系统的模型。基该模型可以进一步设计基于加速度传感器的控制策略,加速度反馈可以控制系统的扰动力对丝杠传动控制精度的影响,实验结果表明提出的方法可以有效地提高丝杠系统的性能。     

单芯片集成加速度计陀螺的研究

讨论单片集成加速度计陀螺的结构及其工作原理，并对单结构加速度计陀螺的加速度信号和陀螺信号的分离进行了阐述．在以往的微型惯性测量组合中，加速度计和陀螺是分离的，这样将产生较大的轴间耦合误差．设计了双质量块振动系统，利用一个敏感头同时测量加速度和陀螺信号．在此基础上讨论了陀螺的驱动电路与信号检测电路．     

地震动加加速度反应谱的概念及特性研究

加加速度是加速度关于时间的变化率,反映了结构受力变化情况。地震动加加速度及其反应谱的研究可以加强人们对地震动非平稳性的认识。阐述了加加速度的力学意义及研究价值,探讨了计算DriDri速度的动力学方法并对其优缺点进行了比较。建立了地震动下弹性及弹塑性加加速度反应谱的求解方法。根据场地类型、放大系数、延性系数及折减系数等影...     

三转动数控台跃度逆解分析

针对机械加工对数控转台的需求,研究3PSS RU并联构型三转动数控台的跃度逆解,以分析驱动系统对数控转台机械结构的柔性冲击和振荡．首先对提出的数控台进行描述,利用矢量方程法建立三转动数控台运动学模型,对其进行位置、速度、加速度逆解计算,在加速度分析的基础上进一步求导进行跃度分析,最后通过给定末端动平台的运动规律,计算出三转动数控台滑块的位置、速度、加速度与跃度随时间变化曲线．结果证实,在给定的运动规律中滑块2的移动范围、速度、加速度与跃度均较滑块1与滑块3的大,表明滑块2所受的冲击和振颤也较大．     

A tool path patching strategy around singular point in 5-axis ball-end milling

In 5-axis high-speed milling, large incoherent movements of rotary axes around the singular point are known to be a problem. Correction methods found in the literature deal mostly with the collision that may happen between the tool and the part but not with the feedrate slowdowns which affect surface quality and machining productivity. The method proposed in this paper addresses both geometrical and productivity issues by modifying the tool axes orientation while respecting maximum velocity, acceleration and jerk of the machine tool axes. The aim is to detect these behaviours and replace the considered portion of the tool path by a patch curve respecting kinematical constraints of the machine tool. Compared to previous works, the inserted patch curve is not constrained to pass through the singularity but respect tangential constraints to ensure the monotony of the tool path and is also connected with the rest of the tool path to ensure a continuity up to the third derivative in order to fulfil jerk limitations. For that purpose, the initial articular positions of the rotary axes around the singular point are fitted with B-spline curves, modified and finally discretised for linear interpolation. Experimental investigations on a test part are carried out to show the efficiency of the method in terms of feedrate and surface quality.     

Extended Kalman filter-based sensor fusion for operational space control of a robot arm

Accurate measurements of positions, velocities, and accelerations in both joint and operational space are required for achieving accurate operational space motion control of robots. Servomotors used for joint actuation are normally equipped with position sensors and optionally with velocity sensors for interlink motion measurements. Further improvements in measurement accuracy can be obtained by equipping the robot arm with accelerometers for absolute acceleration measurement. In this paper, an extended Kalman filter is used for multisensor fusion. The real-time control algorithm was previously based on the assumption of a jerk represented as a processed white noise with the zero mean. In reality, the accelerations are varying in time during the arm motion, and the zero mean assumption is not valid, particularly during fast accelerating periods. In this paper, a model predictive control approach is used for predetermining next-time-step jerk such that the remaining term can be modeled as Gaussian white noise. Experimental results illustrate the effectiveness of the proposed sensor fusion approach.     

Development of a method for detecting jerks in safety critical events

A new method for detecting jerks in safety critical events, based on the characteristics of the braking caused by the driver in time critical situations, has been developed and evaluated in a small pilot test and also applied on a naturalistic driving study. A portable event data recorder, capable of measuring and recording acceleration profiles for a predetermined time period before and after the safety critical situation, has also been developed to ensure high data quality used to evaluate the proposed method. Thus, an analysis of the acceleration profile is possible during the entire braking event. The study involves analyses of acceleration profiles and different characteristics of the rate of change of the acceleration profiles, i.e. jerks, such as negative jerk, used in previous studies, and a peak-to-peak value of the jerk. The finding is that the proposed method provides a more distinct difference between critical and potentially critical events and thus may be an appropriate method used to detect safety critical events.     

Comparison of two iteration procedures for a class of nonlinear jerk equations

A modified Michens iteration procedure and a direct Michens iteration procedure are applied to determine approximate periods and analytical approximate periodic solutions of a class of nonlinear jerk equations. When we use the modified Michens iteration procedure to deal with the nonlinear jerk equations, we need to solve the nonlinear algebra equation for determining the approximate angular frequency. The higher the number of iterations, the more difficult it is to deal with the nonlinear algebra equation. This is because the kth-order approximate solution obtained by the modified Michens iteration procedure is a function of the angular frequency. However, since the kth-order approximate solution obtained by the direct Michens iteration procedure is independent on the kth-order approximate angular frequency, the form of nonlinear algebra equation that determines the kth-order approximate angular frequency of nonlinear jerk equation is similar. The second-order approximate period obtained by the direct Michens iteration procedure provides very accurate results for the large initial velocity amplitudes. But the second-order approximate period obtained by the modified Michens iteration procedure is invalid for all amplitudes B of the initial velocity. A comparison of the first- and second-order approximate periodic solutions obtained by the direct Michens iteration procedure with the numerically exact solutions shows that the second-order approximate periodic solution is much more accurate than the first one. Thus, the direct Michens iteration procedure is very effective for the class of nonlinear jerk equations.     

The rate of change of acceleration: implications to head kinematics during rear-end impacts

Whiplash is a mechanism of injury commonly associated with rear-impact vehicle collisions. To date, research has focused primarily on changes in velocity and acceleration as key factors for determining injuries due to whiplash mechanisms, but other characteristics of the acceleration pulse may be important. This study assessed whether the head acceleration response to whiplash-like perturbation profiles were affected by a change in the rate of the applied acceleration, or jerk. Twenty-one subjects were exposed to different low-velocity rear-impact whiplash-like perturbations using a precisely controlled robotic platform. The perturbations were divided into two groupings of peak acceleration (approximately 10 (high) and 5.7 (low) m/s²) and three groupings of jerk (approximately 260, 310, and 360 m/s³). These six profiles were repeated twice. Results demonstrated that the jerk magnitude significantly affected forehead acceleration in the vertical and horizontal directions. Increasing the magnitude of the platform acceleration also differentially affected the horizontal and vertical forehead accelerations. This indicates that the level of jerk influences the resulting head kinematics and should be considered when designing or interpreting experiments that are attempting to predict injury from whiplash-like perturbations.     

光辐射量值传递系统的建立与新发展

光辐射计量以其独有的特性被广泛的应用于各行各业，从近期的国际比对来看，光辐射参数的计量测试占有相当重要的地位，参数涉及越来越多。从最初的坎德拉到应用广泛的温度、功率及辐射照度等，体现了光辐射计量技术快速发展的同时，也体现了光辐射技术在各个领域的广泛应用。本文主要介绍以探测器为基础的新型的光辐射量传系统，该系统主要以低温辐射计为基准，以各种标准探测器、辐射计等为传递标准对辐射的各个专业进行量值传递，并简要说明了现阶段光辐射计量面临的新问题及其新的发展方向。     

真空计量的新进展

真空计量学已发展成为计量学的一个新的独立分支，其研究内容已从传统的全压力测量与校准扩展到分压力测量与校准、气体微流量(漏率)测量与校准。本文描述了这三个方面的最新进展，从中可看出真空计量学的现状与发展趋势。     

基于激光诊断的分子标记示踪测速技术研究进展

随着飞行器速度的不断提升,高超声速气流流动理论、高超声速燃烧流场分析、飞行器空气动力学特性等研究的重要性日益凸显。目前常规的速度测量方法在面对高超声速复杂流场环境时受到的限制越来越明显,需要研究新的技术以满足流场内精确速度测量需求。分子标记示踪测速技术因其非侵入、无跟随性限制等优势正在成为研究热点。本文阐述了纳秒激光分子标记示踪测速技术、飞秒激光分子标记示踪测速技术的基本原理、主要参数和工作特点,分析了这些技术在测量中所面对的挑战,并对其在科学及工程领域中的应用前景展开了讨论,为推动高超声速复杂流场环境速度测量技术发展提供借鉴。