微型航姿系统中三轴MEMS加速度计组合误差建模方法

根据微机械(MEMS)加速度计的测鲢原理对其误差源进行了分析,并研究了微型航姿系统中加速度计的非正交零偏以及温度特性.基于加速度计输出电压随温度变化的规律,利用分温度段对加速度计进行六位置标定的方法建立加速度计的误差模型,并应用于微型航姿系统,实现加速度计的实时补偿.多次实验结果表明,加速度计的误差模型校正了加速度计的...     

加速度计温度补偿方法

介绍了加速度计温度补偿的几种方法,从加速度计的热设计、温度补偿结构设计、改善加速度计工作环境的措施、建立加速度计温度模型等几个方面对加速度计的温度补偿方法进行了分析和研究.     

用MAX1457实现对硅压阻式加速度计的温度补偿

本文介绍了传感器信号处理器MAX1457的主要功能及其用于对硅压阻式加速度计进行温度补偿的系统组成、补偿方法等。并通过实际补偿结果表明．利用MAX1457对硅压阻式加速度计进行热零点漂移补偿和热灵敏度漂移补偿．有效提高了压阻式加速度计的温度稳定性。     

基于BP神经网络模型的MEMS加速度计误差补偿方法

现阶段普遍采用多元线性回归对加速度计误差建模,并利用最小二乘法对模型参数辨识,但其对加速度计精度提高有限,因此该文提出一种基于BP神经网络模型的MEMS加速度计误差补偿方法。该方法利用BP神经网络建立加速度计误差模型,通过多位置翻滚进行实验数据测量,并对模型进行训练,最后利用训练好的模型对加速度计误差进行补偿。比较多元线性回归和BP神经网络建模对加速计误差补偿结果,其标准偏差分别为0.001 9 g和0.000 16 g。结果表明误差下降一个数量级,说明BP神经网络能有效地补偿加速度计误差。     

基于BP神经网络的磁通门传感器温度误差补偿

三轴磁通门传感器受温度影响明显,严重影响其测量准确度,需要研究补偿方法,提高测量准确性.在不同磁场环境下,利用无磁高低温试验箱对传感器输出值温度特性进行了测试,并采用BP神经网络的方法进行温度补偿.分别阐述了设备操作过程及数据处理方式.采集传感器在不同温度下的测量数据样本;将BP神经网络应用于温度误差模型的非线性辨识,...     

贝叶斯估计在静态倾角计算中的应用

目的:在采用三轴加速度计的倾角测量系统输出值解算中存在灵敏度非线性的情况下,为提高测量精度。方法:通过采集加速度传感器三个轴的测量值,应用三种不同的倾角计算方法对静态倾角进行计算;然后利用贝叶斯估计算法对计算结果进行数据融合计算。结果:融合计算结果的平均误差相比单一解算算法减小了77%以上,且误差分布更均匀。结论:采用贝叶斯估计融合以后的计算结果克服了单一算法固有的灵敏度非线性问题并且进一步降低了测量噪声,有效提高了静态倾角测量系统的测量精度。     

基于椭球假设的三轴加速度计无依托校准方法

针对现有航姿测量系统三轴加速度计校准方法成本高、精度低以及现场校准能力不足的问题,本文提出了一种基于椭球假设的无依托现场校准方法.首先,根据传感器的灵敏度、偏置以及非正交耦合因素对加速度计的影响,建立了误差椭球校准模型.该模型将三轴加速度计的校准过程转化为将椭球面还原成圆球面的几何变换过程,使得校准参数由15个减少到9个,同时克服了部分非正交耦合参数难以辨识的问题.其次,构造了变权值似然目标函数,根据加速度计测量值的方差调整权值大小,从而降低了测量噪声对校准结果的影响.最后,运用粒子群优化(PSO)算法求解几何变换参数的最大似然估计值,并利用椭球校准模型对三轴加速度计进行校准.实验结果表明,采用椭球假设无依托现场校准方法不依赖外部辅助姿态信息,可在现场将航姿测量系统的倾角误差降低为校准前的1/5,满足了航姿系统的使用需求.     

圆箔式辐射热流传感器的温度补偿方法研究

针对目前国内外圆箔式辐射热流传感器在测量过程中由于热沉体温度上升,导致灵敏度下降的问题,提出了一种基于圆柱体一维导热模型的温度补偿方法.首先,阐述了圆箔式辐射热流传感器的测量原理,分析了热沉体温度上升导致传感器输出下降的原因.然后,推导了热沉体的升温过程,构建了圆柱体一维导热的热力学模型,采用了一段特定长度的康铜线,在热沉体末端建立了一对反相串联的T型热电偶对热沉体的温度上升进行补偿.实验结果表明:带温度补偿的传感器比不带补偿的传感器具有更好的稳定性和线性度,表明了该补偿方法的可行性和有效性.     

硅微谐振式加速度计的温度效应及补偿

零偏和标度因数稳定性是衡量加速度计性能的两个重要参数.为了降低硅微谐振式加速度计的温度敏感性,对其温度影响机理进行了深入研究.通过温度实验发现,硅微谐振式加速度计的零偏和标度因数与设计理论参数有较大区别,且都具有较大的温度灵敏度,分别为0.72 g/℃和1.5℃-1.对弹性模量和谐振器应力与谐振器频率的关系进行了理论计算和FEA仿真验证,其中弹性模量引起的谐振频率-温度灵敏度为-0.7 Hz/℃,谐振器应力引起的谐振频率-温度灵敏度为180 Hz/℃.阐述了加工过程中键合应力产生的原因以及键合应力与谐振器残余应力的关系,发现谐振器应力是造成加速度计输出随温度漂移的主要因素.提出了一种隔离残余应力的隔离梁的设计方案,可使零偏温度灵敏度降至-35 Hz/℃,为温度补偿指明了方向.     

基于单片机的数字式热电偶传感器设计

针对热电偶传感器存在的输出热电势信号小、不便于远距离传输,需要进行冷端温度补偿、不便于使用,输出的是模拟信号、不便于实现数字式测量等问题,提出一种基于单片机的测量电路,该电路可对热电偶输出的信号进行测量,并能够自动进行冷端温度补偿,测量结果转换为RS232串行信号向外输出。热电偶传感器配备上该测量电路,便可实现所测温度的数字输出,具有较高的实用性。     

基于加速度计阵列的六自由度振动台测试方法研究

目前多自由度振动台缺乏方便有效的多自由度振动测试手段,通过探讨基于加速度传感器的六自由度振动测试方法,提出基于4只三向加速度计的加速度计阵列构型,依据六自由度运动系统方程对该构型的运动状态进行了理论推导,并设计了具体的封装方法,最后对封装的加速度计阵列构型进行了多自由度振动测试试验验证。试验结果表明:所提出的基于4只三向加速度计的加速度计阵列构型能够对角加速度进行测试与还原,简易可靠,可以作为多自由度振动的测试手段。本文提出的加速度计陈列构型有望被推广应用于现场低频振动测量或校准工作中。     

一种摆式加速度计结构模态分析

利用ANSYS软件对一种单轴摆式加速度计的结构进行了有限元分析,得出了各阶模态下加速度计结构的固有频率和振型,找到了处于该型加速度计通频带之内的模态频率。然后,对加速度计进行了结构优化,使各阶模态频率处于通频带之外,为加速度计的结构改进提供了理论依据。     

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%。     

基于栅结构谐振器的X和Y轴加速度及Z轴角速度的组合测量

本文利用一由两个相互垂直的加速度计组成的栅结构谐振器来同时测量z轴和Y轴的加速度以及z轴的输入角速度．此谐振器利用变面积电容进行检测,具有良好的线性度及快速的信号响应．此谐振器的x轴及Y轴的加速度计的谐振频率分别为1．9315kHz和1．8403kHz．在初始状态下,Ⅳ轴的加速度计被驱动进入谐振状态,且Y轴的加速度随着x轴的加速度计一起振动．当=轴存在角速度输入时,Y轴的加速度计会相应地沿Y轴进行振动,而x轴及Y轴的加速度会改变相应轴上加速度计的平衡位置．测试结果表明,此器件的z轴角速度灵敏度为16mV／（（9）·s-1）,x和Y轴的加速度灵敏度分别为49mV／g和244mV／g．z轴角速度输出的噪声等效角速度为0．0138（s·／Hz-1）,x和Y轴加速度输出的噪声等效加速度为0．42X10-3g／／Hz和0．074X10-3。g／√Hz．     

Single-Wafer-Processed Self-Testable High-$g$ Accelerometers With Both Sensing and Actuating Elements Integrated on Trench-Sidewall

A single-wafer-processed high-$g$ piezoresistive accelerometer is reported. The microsensor has an in-plane self-caging cantilever configuration, in which an electrostatic self-testing function is integrated on-chip. Both the sensing piezoresistors and the self-test actuating electrodes are integrated on vertical sidewalls of the laterally deflecting cantilever. For single-wafer-based fabrication of the self-testable piezoresistive accelerometer, a trench-sidewall micromachining technology is developed, which is capable of integration of both boron-diffused piezoresistive sensors and electrostatic actuators on deep trench sidewalls. In addition, the technology can realize electrical continuity from the vertical trench-sidewall to the wafer surface. After design and fabrication of the accelerometers for a 200 000 g measure-range, characterization was performed to evaluate the developed trench-sidewall integration technology and to test the self-testable high-$g$ accelerometers. A linear I-V relationship for the sidewall-diffused piezoresistor is measured with satisfactory sidewall-to-surface electric-transfer properties. The electrical isolation between adjacent elements on the sidewall shows a breakthrough voltage of about 55 V. Moreover, with the single-chip integrated lateral-actuating structure, both static and dynamic self-testing functions are realized. The measurement of the accelerometer results in a sensitivity of about 1 $~mu$V/g/3.3 V, noise-limited vibration resolution of about 1 g and zero-point temperature drift of lower than 100 ppm/$^{circ}$ C.      

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.     

高g值加速度传感器激光绝对法冲击校准技术研究

在详细分析反射式激光多普勒原理的基础上,研究了高g值加速度传感器的冲击校准方法。该方法利用Hopkinson杆作为加载手段,利用差动式激光多普勒干涉仪来绝对复现冲击加速度的量值。针对高g值压阻加速度传感器SIMIT-AYZ-60k进行了一系列的校准试验,利用积分运算法和最小二乘法的组合从准动态条件下的校准数据得到了准静态条件下的传感器冲击灵敏度。试验表明,这种方法实现了利用脉宽有限的激励脉冲对固有频率在20kHz以上的高g值加速度传感器的校准,校准的不确定度可以满足冲击测试的工程需求。     

Drop Tower Microgravity Improvement Towards the Nano-g Level for the MICROSCOPE Payload Tests

The Bremen drop tower at the Center of Applied Space Technology and Microgravity (ZARM) provides high quality micro-g condition needed for many high precision tests. This is even more improved by the development of a free flyer technology. This new technology is used for a free fall test of the MICROSCOPE differential accelerometers which only can work with a residual acceleration disturbance level below 25 nano-g in the high resolution mode. The French MICROSCOPE space mission for testing the Weak Equivalence Principle is scheduled for 2012/2013. The free fall accelerometer test campaign at ZARM is an important part of the pre-mission test program. In this article the new free flyer technology, its performance as well as the accelerometer tests are described.     

Absolute calibration of accelerometers at high frequencies

This paper describes the calibration of commercial accelerometers with mass load by laser interferometry at frequencies ranging from 2 kHz to 10 kHz. It is shown by experiment that the effect of mass load on the frequency response of commercial accelerometers with inverted centre mounted compression design is negligible. The comparison method adopted by some foreign companies has been analysed and the relative motion between the top of the mass load and the upper surface of a commercial accelerometer has been measured, thus explaining the obvious errors in frequency response curves obtained by using the comparison method.     

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.