基于MEMS加速度计与磁力计的位移计设计

基坑水平位移监测是基坑安全的重要检测项目之一。针对现有的阵列式位移计在基坑水平位移监测中容易产生扭转误差的问题,设计了一种基于MEMS加速度计与磁力计的位移计,能够同时满足基坑水平位移与沉降位移监测的需求。介绍了位移计自动化实时监测系统组成。对位移计的结构以及监测节的硬件电路进行了设计,并制作完成了位移计样机。阐述了位移计通过对加速度计与磁力计的数据进行融合,计算位移坐标的测量原理和扭转误差校正的方法。最后通过模拟监测节间发生扭转时位移计水平位移监测的实验,以及位移计沉降位移监测试验。实验结果表明,该位移计能够精确测量水平与沉降位移,并能够有效校正位移计竖直安装时监测节扭转带来的扭转误差。

MEMS加速度计全温性能优化方法

针对微机电系统(MEMS)加速度计全温性能低的问题,提出锚区应力对消方法、低应力粘接工艺和温度补偿方法。首先,通过调整两个键合的锚区面积大小实现锚区应力对消,使得加速度计的温度性能得到改善;然后,建立加速度计堆叠封装模型并对专用集成电路(ASIC)粘接参数、加速度计敏感结构点胶方式与点胶参数进行仿真分析,从而确定了加速度计的低应力粘接形式和粘接工艺;最后,对加速度计零偏和标度因数设计了三阶温度补偿方法并进行了实验测试。实验结果表明,加速度计全温零偏稳定性达到47.3μg(1σ)、全温标度因数稳定性达到43.6 ppm(1σ),提高了加速度计的全温性能。

一种用于振动测量的MEMS电磁式加速度计

基于电磁感应原理,设计并制备了一种用于振动测量的微机电系统(MEMS)电磁式加速度计,其具有无源、集成度高、对加工工艺精度要求低及不受温度、湿度影响等优势。首先通过有限元分析软件对加速度计敏感结构及永磁体磁场进行仿真分析,然后利用MEMS微加工工艺制备敏感结构及电磁线圈等主要部件,将加速度计芯片与嵌有永磁体的陶瓷基板进行键合封装。通过敏感结构受到振动并带动线圈相对永磁体发生位移产生电压信号。最后通过振动测试系统对电磁式加速度计的灵敏度、量程、线性度及抗过载能力等动态参量进行评估。实验结果表明,在0~3g量程范围内,加速度计可实现对63~69 Hz频率振动的测量,灵敏度最高为263 mV/g,非线性误差为3.3%,可用于恶劣环境下低g值的振动测量。

一种分时差分的频率调制MEMS加速度计

为提升MEMS加速度计温度适应性,设计了频率调制和分时差分方法。基于静电刚度效应,将敏感质量块因加速度产生的位移变化调制成谐振频率的变化,兼顾了位移检测的温度系数较低与谐振频率检测不易受电路噪声干扰的优点,且采用单个谐振器在时间上通过刚度切换进行分时差分,从而降低零偏随温度的漂移。通过实验测得,在10 V调谐电压下,加速度计室温下的零偏稳定性为76.79μg。-40℃~60℃全温范围内经过分时差分后得到的频差全温变化量为-0.072 Hz,相较于单个刚度状态下的谐振频率变化约7.7 Hz,减小了约99%,验证了静电刚度频率调制和分时差分的有效性。

System-Level Modeling and Simulation of Force-Balance MEMS Accelerometers

This paper presents two approaches for system-level simulation of force-balance accelerometers. The derivation of the system-level model is elaborated and simulation results are obtained from the implementation of those strategies on the fabricated silicon force-balance MEMS accelerometer. The mathematical model presented is implemented in VHDL- AMS and SIMULINK TM,respectively. The simulation results from the two approaches are compared and show a slight difference. Using VHDL-AMS is flexible,reusable,and more accurate. But there is not a mature solver developed for the language and this approach takes more time, while the simulation model can be easily built and quickly evaluated using SIMULINK.

用于三轴MEMS加速度计的集成数字调理电路

基于0.18μm互补金属氧化物半导体(CMOS)工艺,设计了一种用于三轴微电子机械系统(MEMS)加速度计的集成数字调理电路,实现了三轴加速度信号的数字后处理。该数字调理电路采用级联积分梳状(CIC)与有限冲击响应(FIR)相结合的滤波器形式,有效滤除了带外的量化噪声,提高了输出信号的信噪比;零位采用四阶多项式拟合温补算法,标度因数采用二阶多项式拟合温补算法,有效降低了加速度输出随温度的漂移,提升了加速度计的测量精度。此外,FIR滤波器采用时分复用的实现形式,温补模块采用串行实现形式,有效减小了芯片面积,最终芯片面积为1.5 mm^(2)。测试结果表明,滤波器符合设计值,三轴MEMS加速度计的零偏不稳定性为15μg,速率随机游走为0.035 m/s/√h,温补后零偏全温区变化量为3.55mg,提升了5.4倍;温补后标度因数全温区变化量为0.0026,提升了4.1倍,电路性能良好。

一种用于MEMS加速度计温度性能提升的双质量全差分结构

微电子机械系统(MEMS)加速度计作为应力敏感器件,很容易受到外界应力的影响,尤其是对温度应力非常敏感,MEMS加速度计的温度性能成为了制约加速度计性能提升的关键因素。为了提高MEMS加速度计的温度性能,减小温度漂移,提出了一种新型的双质量、全差分MEMS敏感结构方案。通过双质量的差分效果,可以将外界温度变化引起的变形差分掉,从而降低加速度计的温度系数,提高温度性能。利用有限元仿真的手段,优化双质量结构的布局,验证加速度计的温度漂移结果。实验结果表明,加速度计温度性能得到了有效提升。

基于MEMS工艺的微热加速度计和微热陀螺仪的制备

微热加速度计和微热陀螺仪两者传感芯片结构相似,并且制备工艺完全兼容,在同一块绝缘体上硅(SOI)基板上运用同一工艺流程同时制备出了微热陀螺仪传感芯片和微热加速度计传感芯片。为了准确地创建微尺度的图案和结构,设计了四块光刻掩模版来制作该微热加速度计芯片和微热陀螺仪芯片,分别对应于接触孔开口、热敏电阻、互连布线和背面空腔。轻掺杂硅热敏电阻的可控电阻温度系数(TCR)大于传统金属丝,因此选择p型硅作为热敏电阻材料。TCR由硅片的掺杂浓度决定,使用了三种不同掺杂浓度的硅片进行对比实验,从而选定硅片的掺杂浓度为1×10^(17)cm^(-3),对应的TCR为3500×10^(-6)/℃。选择SOI作为衬底材料,显著增强了微热陀螺仪和微热加速度计的耐高温性,并且提高了其灵敏度。在电感耦合等离子体-反应离子刻蚀(ICP-RIE)和氢氟酸(HF)蒸气工艺过程中,通过光刻胶和聚酰亚胺层成功保护了非常薄和易碎的热敏电阻,在4英寸(1英寸=2.54 cm)SOI基板上一次最多可以成功制备出180个微热陀螺仪传感芯片和108个微热加速度计传感芯片,制备的微热加速度计传感芯片尺寸为2 mm×2 mm×0.4 mm,微热陀螺仪传感芯片尺寸为5.8 mm×5.8 mm×0.4 mm。分别对制备的微热加速度计和微热陀螺仪进行了测试,微热陀螺仪x轴灵敏度为0.107 mV/(°/s),y轴灵敏度为0.102 mV/(°/s),微热加速度计灵敏度为13 mV/g。通过一次工艺流程制备出两种热流体惯性传感器,极大地缩短了制备时间,降低了制备成本,成功实现了高精度的批量生产。

基于六位置法和KF的MEMS加速度计补偿方法

MEMS传感器以其体积小、廉价等优点备受关注,然而,其误差相对较高。由于相同规格的MEMS惯性传感器存在误差特性的差异,建立准确的传感器误差模型成为一项颇具挑战性的任务。低准确度的MEMS惯性传感器误差,主要涉及零偏、标准化规范影响因数和相对较大的安装偏差。为克服这种误差源,文章提出一种采用Kalman滤波和六位法的MEMS加速度计补偿方法。实验结果表明,MEMS加速度计在补偿后输出的误差明显减小。横滚角在-90°~+90°范围内变化的绝对误差在应用该方法后,由补偿前的2.44°减小至0.64°。

高冲击下MEMS加速度计的柔性止挡结构设计

止挡结构是提升MEMS加速度计冲击可靠性的常用技术之一。由于在高冲击载荷作用下会发生断裂,因此,本文通过动力学仿真设计了柔性止挡结构,并将质量块上的冲击碰撞区域设计为三根柔性梁和三个止挡凸台。同时,基于ANSYS动力学模块,分析了10000g半正弦加速度作用下的质量块与其之间的碰撞行为。结果表明:该结构的键合面上的最大剪切应力为4.16MPa,低于硅-玻璃阳极键合界面的剪切强度,且柔性梁上的最大主应力为0.13GPa,低于单晶硅的拉伸强度。因此,可达到预期目标。

Fabrication and Characterization of Tunneling Current of Anodic Bonded Dry-Etched MEMS Tunneling Accelerometer

A tunneling accelerometer is fabricated and characterized based on the extension of the silicon-glass anodic-bonding and deep etching releasing process provided by Peking University.The tunneling current under open loop operation is tested in the air by HP4145B semiconductor analyzer,which verifies the presence of tunneling current and the exponential relationship between tunneling gap and tunneling current.The tunneling barrier is extrapolated to be from 1.182 to 2.177eV.The threshold voltages are tested to be 14～16V for most of the devices.The threshold voltages under -1,0,and +1g are tested,respectively,which shows the sensitivity of the accelerometer is about 87mV/g.

Suitable triggering algorithms for detecting strong ground motions using MEMS accelerometers

With the recent development of digital Micro Electro Mechanical System （MEMS） sensors, the cost of monitoring and detecting seismic events in real time can be greatly reduced. Ability of MEMS accelerograph to record a seismic event depends upon the efficiency of triggering algorithm, apart from the sensor＇s sensitivity. There are several classic triggering algorithms developed to detect seismic events, ranging from basic amplitude threshold to more sophisticated pattern recognition. Algorithms based on STA/LTA are reported to be computationally efficient for real time monitoring. In this paper, we analyzed several STA/LTA algorithms to check their efficiency and suitability using data obtained from the Quake Catcher Network （network of MEMS accelerometer stations）. We found that most of the STA/LTA algorithms are suitable for use with MEMS accelerometer data to accurately detect seismic events. However, the efficiency of any particular algorithm is found to be dependent on the parameter set used （i.e., window width of STA, LTA and threshold level）.

Summary of Research Status and Application of MEMS Accelerometers

The rapid development of MEMS technology has made MEMS accelerometers mature and the application range has been expanded. Many kinds of MEMS accelerometers are researched. According to the working principle of MEMS accelerometer, it can be divided into: piezoresistive, piezoelectric, capacitive, tunnel, resonant, electromagnetic, thermocouple, optical, inductive, etc. Due to its outstanding features in terms of size, quality, power consumption and reliability, MEMS sensors are used in military applications and where high environmental resistance is required. MEMS accelerometers are developing rapidly and have good application prospects. In order to make MEMS accelerometers more widely understood, the advantages of MEMS accelerometers are expounded. The research status of MEMS accelerometers is introduced, and MEMS are analyzed. The application of accelerometers in real-world environments, and the development trend of MEMS accelerometers in the future. More scholars will invest in MEMS accelerometer research, pursuing high performance, low power consumption, high precision, multi-function, and interaction. Strong MEMS accelerometers will be ubiquitous in the future.

Lumped parameter analytic modeling and behavioral simulation of a 3-DOF MEMS gyro-accelerometer

A new analytical model of a 3-degree-of-freedom （3-DOF） gyro-accelerometer system consisting of a 1-DOF drive and 2-DOF sense modes is presented. The model constructs lumped differential equations associated with each DOFof the system by vector analysis. The coupled differential equations thus established are solved analytically for their responses in both the time and frequency domains. Considering these frequency response equations, novel device design concepts are derived by forcing the sense phase to zero, which leads to a certain relationship between the structural frequencies, thereby causing minimization of the damping effect on the performance of the system. Furthermore, the feasibility of the present gyro-accelerometer structure is studied using a unique discriminatory scheme for the detection of both gyro action and linear acceleration at their events. This scheme combines the formulated settled transient solution of the gyro-accelerometer with the processes of synchronous demodulation and filtration, which leads to the in-phase and quadrature components of the system＇s output signal. These two components can be utilized in the detection of angular motion and linear acceleration. The obtained analytical results are validated by simulation in a MATLAB/Simulink environment, and it is found that the results are in excellent agreement with each other.

A Survey of Error Analysis and Calibration Methods for MEMS Triaxial Accelerometers

MEMS accelerometers are widely used in various fields due to their small size and low cost,and have good application prospects.However,the low accuracy limits its range of applications.To ensure data accuracy and safety we need to calibrate MEMS accelerometers.Many authors have improved accelerometer accuracy by calculating calibration parameters,and a large number of published calibration methods have been confusing.In this context,this paper introduces these techniques and methods,analyzes and summarizes the main error models and calibration procedures,and provides useful suggestions.Finally,the content of the accelerometer calibration method needs to be overcome.

Multiple dependent reliability estimation of large range MEMS accelerometers in high temperature environment

In the past,only one performance parameter was considered in the reliability estimation of micro-electro-mechanical system (MEMS) accelerometers,resulting in a one-sided reliability evaluation. Aiming at the failure condition of large range MEMS accelerometers in high temperature environment,the corresponding accelerated degradation test is designed. According to the degradation condition of zero bias and scale factor,multiple dependent reliability estimation of large range MEMS accelerometers is carried out. The results show that the multiple dependent reliability estimation of the large range MEMS accelerometers can improve the accuracy of the estimation and get more accurate results.

基于IAO的随钻MEMS加速度计误差参数识别方法

针对随钻测量中MEMS加速度计器件误差变化难以精确识别的问题,提出一种基于改进天鹰算法(IAO)的随钻MEMS加速度计误差参数识别方法。首先根据MEMS加速度计输出模型变换得到非线性误差函数,采用天鹰算法(AO)求解到非线性误差函数的最优值。在AO算法基础上,利用误差参数平均值和迭代次数改善AO算法开采参数的全局搜索能力,基于误差参数最优值和平均值构造径向因子提高AO算法误差参数识别精度。然后采用IAO算法极限逼近非线性误差函数的参数最优值,并通过采样点插值误差数据库完成误差参数校准。最后将IAO算法应用于识别加速度计误差参数,结果表明:IAO算法识别精度比PSO算法、SSA算法和AO算法提高了1~2个数量级,补偿后的加速度计输出误差明显减小。

Comprehensive Warpage Analysis of Stacked Die MEMS Package in Accelerometer Application

Packaging of MEMS ( micro-electro-mechanical system ) devices poses more challenges than conventional IC packaging, since the performance of the MEMS devices is highly dependent on packaging processes. A Land Grid Array ( LGA ) package is introduced for MEMS technology based linear multi-axis accelerometers. Finite element modeling is conducted to simulate the warpage behavior of the LGA packages. A method to correlate the package warpage to matrix block warpage has been developed. Warpage for both package and sensor substrate are obtained. Warpage predicted by simulation correlates very well with experimental measurements. Based on this validated method, detailed design analysis with different package geometrical variations are carried out to optimize the package design. With the optimized package structure, the packaging effect on accelerometer signal performance is well controlled.

基于RBF的MEMS加速度计温控系统设计

针对微机电系统(MEMS)加速度计受到温度变化影响较大、产生不同程度的漂移和测量误差,难以满足工业机器人领域高精度导航的问题,提出一种提高MEMS精度的温度补偿方法。利用热电制冷器设计适用于嵌入式的温度控制系统,使MEMS传感器的工作温度相对稳定。利用MPU6050的MEMS加速度计,设计一种基于STM32主控的嵌入式温度控制系统,并通过上位机采集数据,对比分析改进径向基函数(RBF)、RBF和常规PID等算法的温控效果。结果表明:在当前的PID控制参数的条件下,改进的RBF整定效果相对于RBF-PID和经典PID,在超调量、稳态误差、调节时间等指标上,表现出更优的系统响应和控制精度,超调量降低41.3%,调整时间减低52.3%,系统对温度的控制精度约为0.04℃。

一种振动测量用电容式硅基MEMS加速度计

为了解决目前微电子机械系统(MEMS)加速度计在振动测量领域量程小和振动测量精度低等问题,基于绝缘体上硅(SOI)加工工艺,设计并制作了一款梳齿电容式MEMS加速度计。通过提高工作模态频率和干扰模态频差,提升了加速度计振动环境适应性;加速度计量程达到±50g,非线性度0.2%,横向灵敏度0.17%,分辨率优于0.5mg,体积9 mm×9 mm×2.7 mm,功率损耗30 mW。针对随机振动环境对加速度计的输出精度进行了实验验证,结果表明,MEMS加速度计与标准传感器的输出误差为2.69%,能够满足大部分工程应用需求。