传感器阵列六自由度振动测试数值积分误差消除方法研究

利用多个加速度计组成的传感器阵列进行复杂振动测试,多组加速度计测试值可求解被测物质心线加速度及相对载体坐标系三轴方向转动角速度。对角速度、线加速度积分可求解被测物任意时刻相对于固定坐标系位置及姿态,达到六自由度复杂振动测试目的。针对积分过程中存在积分误差及随测试时间增加积分误差迅速增大导致速度、位移信号严重偏离实际问题,利用EMD分解获得多组经验模态分量(IMF),据IMF分量频率不同判断出积分误差成分并分离,获得实际积分结果。     

基于传感器阵列的振动测试角速度算法研究

针对较高频率下多维线振动与角振动同时存在的复杂振动,加速度传感器阵列可以有效地测试六自由度参数.在关键的测试三维角速度的过程中,传统的积分方法使误差快速积累,在长时间测试的情况下严重影响精度.该文基于一种利用三轴加速度传感器阵列的四传感器配置方案,通过模型仿真对积分法、开方法等角速度解算算法进行比较,并提出一种组合算法,在保证精度的前提下解决了误差积累的问题,为长时间的振动测试提供了算法保证.     

三轴加速度传感器阵列振动测试新方案

针对加速度传感器阵列测试较高频率下多维线振动与角振动同时存在的复杂振动六自由度参数的过程中,多个单轴传感器的使用会引入多个安装误差,使系统对于空间大小的要求过于严格,同时增加了计算量等问题,提出一种利用三轴加速度传感器替代单轴加速度传感器的新阵列方案,在对以上限制因素有效改进的同时,简化了阵列结构.通过原理推导与实例仿真验证了新方案是可行的.     

独立卡尔曼滤波器全加速度计复杂振动角速度解算

对于运动体的多自由度振动测试,准确的振动角速度是复杂振动参数解算的关键。针对目前解算角速度单一方法测试精度不理想的问题,分析由4个三轴加速度计组成传感器阵列,测试角速度解算算法,设计一种独立的卡尔曼滤波器用于角速度解算。通过仿真及实验证明:该方法解算结果的误差最大值和标准差相对于单一方法可提高1个数量级,其得到的角速度幅值准确性和曲线平滑度也优于其他单一解算方法。     

平面传感器阵列测试振动角速度算法研究

针对平面加速度传感器阵列测量空间内高频复杂六自由度振动的新方案,提出一种将多种算法融合的组合算法。由于新方案中加速度计的安装位置在一个平面内,直接解算不能得到完整的振动参数,因此结合积分法、开方法进行设计,并最终得到完整的角速度解算数据。通过分析传感器输出方程中数据的内在联系,将解算数据不断更新迭代,保持解算数据的实时性和精确性。其在较长时间的仿真过程中误差始终保持在10-4量级,同时解决积分法的误差积累问题和开方法的符号误判问题。组合算法的设计,可保证平面内配置加速度传感器阵列进行振动测试的可行性。     

基于六自由度振动台的车辆构架运动姿态测量

轨道几何动态检测是保障列车安全运营的重要手段，而车辆构架运动姿态测量结果的准确性直接影响到轨道几何动态检测的可靠性。为提高车辆构架运动姿态检测的准确性，提出了一种基于六自由度振动台的构架运动姿态测量方法。在模拟构架上施加不同的激励信号，利用安装测点布置位置上的4个三轴加速度计采集加速度信号，通过快速傅里叶变换的频域积分方法和基于位移数据的姿态计算算法，将加速度信号转化为模拟构架几何中心的位移及转角，并以六自由度振动台的输入信号作为标准，开展构架姿态测量方法的验证试验，结果表明构架姿态测量算法的横向位移、垂向位移、侧滚、摇头中误差分别小于0.04 mm, 0.03 mm, 0.05°,0.03°。     

基于离心-振动复合装置的加速度计整流误差校准

通过对加速度计传统整流误差校准方法的分析研究,提出了基于离心-振动复合加速度输入的加速度计整流误差校准方案。并通过建立加速度计的非线性耦合模型,给出恒加速度和振动加速度复合作用下加速度计整流误差计算方法。利用研制的离心-振动复合校准装置, 进行了恒加速度和振动加速度复合作用下加速度计的整流误差试验,结果验证了基于恒加速度和振动加速度复合输入的加速度计整流误差校准方法的合理性和可行性。     

人体6自由度运动参数无线测试系统BTViewer的设计与开发

为解决测试人体在三维空间中的关节运动参数,自主设计了人体六自由度运动参数测试系统BTViewer.基于惯性传感器跟踪技术,设计了整体的系统平台工作流程,同时完成了相关算法.为降低误差、减少漂移现象,本实验采用集成的三轴加速度计、三轴磁力计的模块LSM303DLH以及三轴陀螺仪动态采集样本数据,通过无线装置传输到电脑,有效合理地对采集到的数据进行预处理,将原始数据互补滤波之后解析成实际数据,准确地得到人体六自由度运动参数.最后,运用Qt集成的OpenGL等模块进行曲线、三维等可视化显示.实验表明,该系统的设计达到了预期的要求,能够较好地跟踪人体6自由度运动参数.     

高斯流场中单自由度线性体系非高斯振动响应试验研究

对于风湍流等高斯分布流速场中的线性结构体系,当考虑荷载中脉动流速二次项的影响时,理论上其振动响应将呈现非高斯分布特性。基于调试得到的不同粗糙工况高斯流场,开展了单自由度线性体系顺流向振动响应测试,研究了单自由度线性体系加速度响应的非高斯分布特性,分析了粗糙度对响应非高斯成分的影响,讨论了三种常见非高斯概率密度逼近方法对响应的拟合效果。试验结果表明:试验高斯流场中单自由度线性体系的顺流向加速度响应主要呈现出尖峰非高斯分布特征,且随着紊流度的提高,响应非高斯性有增强的趋势;响应的非高斯概率密度宜采用高斯混合模型方法进行拟合。     

加速度计整流误差校准方法

整流误差是衡量外部振动对加速度计性能影响的重要指标。传统的整流误差校准方法,采用单方向、纯振动的激励来进行整流误差校准。此类方法难以真实评价振动噪声的影响。通过对传统整流误差校准方法进行研究,本文提出了一种基于多方向复合加速度输入的加速度计整流误差校准方法,有效解决了加速度计整流误差的校准。     

The effect of coplanar sensor spacing on determining the angular acceleration of vehicles

Vehicle vibration presents challenges to a packaged product that is inevitable in any distribution environment. Typically products are tested in only a single, vertical axis; researchers have shown that there is energy in all six axes of motion. In this work, we study the recording methods of the six degrees of freedom (6DOF) motion of a transport vehicle. Using a co-planar sensor array, three tri-axial linear accelerometers and three angular rate sensors mounted in a L shape are used to calculate the rotational accelerations that occur in the back of a vehicle. Missing from prior work is a scientific study designed to determine the minimum sensor spacing necessary to accurately capture the yaw, pitch, and roll of transport vehicles. A sensitivity study is conducted to determine the effect of the misplacement and misorientation of sensors on the angular acceleration calculation. A laboratory study is used to determine the distance error begins to accumulate in the angular acceleration calculation in response to a sinusoidal input. A field study is conducted to calculate the rotational motions of a vehicle on a rough road. It is found that a mounting fixture is valuable in assuring the necessary sensor placement accuracy needed to accurately determine angular accelerations of a truck. Additionally, laboratory and field analysis show that as the sensor spacing location approaches the origin sensor, angular acceleration calculation error increases due to a loss in distinctiveness. It is desired for a close sensor mounting array, but there is a trade off between measurement accuracy and compactness of the recording array. A limit exists where the sensors can not be mounted in close proximity.     

基于正弦激励的压电加速度计模型参数辨识

针对压电加速度计常规校准无法完全满足实际机械动态量测量要求的问题,采用基于加速度计模型参数校准的方法。参数未知的线性二阶微分方程用来表示加速度计动态特性,利用绝对法振动校准加速度计频率响应数据,采用最小二乘算法确定了未知的参数的值,同时利用蒙特卡罗法确定了参数值的不确定度。最后对加速度计进行了瞬态冲击加速度校准,计算辨识所得模型在相同冲击激励下的预测输出。结果表明:瞬态冲击加速度校准与计算辨识模型结果相差不超过1%。     

Verification of the Microgravity Active Vibration Isolation System based on Parabolic Flight

The Microgravity active vibration isolation system (MAIS) is a device to reduce on-orbit vibration and to provide a lower gravity level for certain scientific experiments. MAIS system is made up of a stator and a floater, the stator is fixed on the spacecraft, and the floater is suspended by electromagnetic force so as to reduce the vibration from the stator. The system has 3 position sensors, 3 accelerometers, 8 Lorentz actuators, signal processing circuits and a central controller embedded in the operating software and control algorithms. For the experiments on parabolic flights, a laptop is added to MAIS for monitoring and operation, and a power module is for electric power converting. The principle of MAIS is as follows: the system samples the vibration acceleration of the floater from accelerometers, measures the displacement between stator and floater from position sensitive detectors, and computes Lorentz force current for each actuator so as to eliminate the vibration of the scientific payload, and meanwhile to avoid crashing between the stator and the floater. This is a motion control technic in 6 degrees of freedom (6-DOF) and its function could only be verified in a microgravity environment. Thanks for DLR and Novespace, we get a chance to take the DLR 27th parabolic flight campaign to make experiments to verify the 6-DOF control technic. The experiment results validate that the 6-DOF motion control technique is effective, and vibration isolation performance perfectly matches what we expected based on theoretical analysis and simulation. The MAIS has been planned on Chinese manned spacecraft for many microgravity scientific experiments, and the verification on parabolic flights is very important for its following mission. Additionally, we also test some additional function by microgravity electromagnetic suspension, such as automatic catching and locking and working in fault mode. The parabolic flight produces much useful data for these experiments.     

A reduced modal parameter based algorithm to estimate excitation forces from optimally placed accelerometers

This paper presents a time domain technique for estimating dynamic loads acting on a structure from acceleration time response measured experimentally at a finite number of optimally placed accelerometers on the structure. The technique utilizes model reduction to obtain precise load estimates. The structure essentially acts as its own load transducer. The approach is based on the standard equilibrium equations of motion in modal coordinates. The modal parameters of a system – natural frequencies, mode shapes and damping factors – can be estimated experimentally from measured data, analytically for simple problems, or using the finite element method. For measurement of the acceleration response, there can be a large number of locations on the structure where the accelerometers can be mounted, and the precision with which the applied loads are estimated from measured acceleration response may be strongly influenced by the locations selected for accelerometer placements. A solution approach, based on the construction of D-optimal designs, is presented to determine the number and optimum locations of accelerometers that will provide the most precise load estimates. An improvement in the algorithm, based on reduced modal matrix, is further proposed to reconstruct the input forces accurately. Numerical examples that help understand the main characteristics of the proposed approach are also presented. The numerical results illustrate the effectiveness of the proposed technique in accurately recovering the loads imposed on discrete as well as continuous systems.     

基于外差激光干涉法的三轴向振动绝对校准方法研究

与单轴向振动激励相比,三轴向标准振动台能够模拟被校三轴向加速度计的实际应用环境。利用三轴向标准振动台获取被校加速度计真实的空间响应特性,以实现被校加速度计的精确校准。立足于加速度矢量理论与三轴向加速度计的灵敏度矩阵模型,提出基于带通采样的外差激光干涉法的三轴向振动绝对校准方法,通过计算被校加速度计的灵敏度矩阵实现其校准。实验结果表明,该方法能够同时实现高精度的三轴向加速度计主轴与横向灵敏度的校准,有效地降低了校准时间与重复安装误差。     

Testing Transverse Sensitivity of Linear Single-Axis Pendulous Accelerometer with Double Turntable Centrifuge

Current ISO standard methods for testing transverse sensitivity of accelerometers are vibration-based. They have difficulties in producing low-frequency vibration for various reasons. This paper introduces a double turntable centrifuge (DTC) to test the accelerometer transverse sensitivity at low frequencies (from 0.01 to 10 Hz). The proposed method can avoid limitations of traditional vibration-based schemes for transverse sensitivity test. In this paper, a theoretical analysis of the method is followed by a presentation of the experimental set-up, and the measurement procedure of a linear single-axis pendulous accelerometer. According to the theoretical analysis and experimental results, it is practicable to test the low-frequency transverse sensitivity with a DTC. The method proposed here can test accelerometer transverse sensitivity at low-frequency with large amplitudes (up to 700 m/s²), and directly measure the angle of the transverse sensitivity with high resolution. It can be a supplement to the standard methods for testing accelerometer transverse sensitivity at low-frequency.     

用于运动姿势捕捉的可穿戴MEMS微型化加速度计研制

在人体上穿戴加速度计能够实现对人体运动姿势捕捉,进而在体育教学和运动训练中有利于提升教学和训练效果,而加速度计的固有频率和测量灵敏度存在相互制约的关系。为此,研制一种孔缝复合八梁结构的MEMS加速度计。该加速度计质量块由四根宽大的支撑梁和四根短小的敏感梁共同支撑,在敏感梁上引入应力集中孔。采用离子注入、背腔干法刻蚀、ICP刻蚀、金属溅射、阳极键合等工艺制作加速度计芯片,并对芯片进行封装。分别采用离心机测试法和简谐激励法对加速度计的静态性能和动态性能进行测试。结果表明,该加速度计的单位电压灵敏度达到0.21 mV/(g·V),固有频率高达14.22 kHz,同时拥有高灵敏度和高频响性能。     

具有分布质量的双层隔振系统隔振特性分析

研究了分布质量对双层隔振系统隔振特性的影响，得到了质量对称分布时六自由度双层隔振系统固有频率及对谐波激励响应的解析表达式，提出了考虑摆动影响时确定隔振参数的实用设计方法并进行了实例计算。