A novel micro-accelerometer with adjustable sensitivity based on resonant tunnelling diodes

Resonant tunnelling diodes （RTDs） have negative differential resistance effect, and the current-voltage characteristics change as a function of external stress, which is regarded as mesc-piezoresistance effect of RTDs. In this paper, a novel micro-accelerometer based on AlAs/GaAs/In0.1Ga0.9As/GaAs/AlAs RTDs is designed and fabricated to be a four-beam-mass structure, and an RTD-Wheatstone bridge measurement system is established to test the basic properties of this novel accelerometer. According to the experimental results, the sensitivity of the RTD based micro-accelerometer is adjustable within a range of 3 orders when the bias voltage of the sensor changes. The largest sensitivity of this RTD based miero-accelerometer is 560.2025 mV/g which is about 10 times larger than that of silicon based micro piezoresistive accelerometer, while the smallest one is 1.49135 mV/g.

Analysis for Transverse Sensitivity of the Microaccelerometer

For the microaccelerometer, strong axial response and weak cross-axial one are always expected. This paper presents a general analysis about transverse sensitivity of the microaccelerometer. The analysis model is developed, where the influence of response stiffness and damping in different axes, as well as symmetrical decline angles of 3 degrees of freedom system is considered. Moreover, multi-freedom vibration equations based on the analysis model are established. And the equations are solved on condition that damping force is ignored. Finally, the theoretical analysis about transverse sensitivity is accomplished, and some effective methods, which are beneficial to reduce cross disturbance, are provided.

Ultra-High Sensitivity Viscometer Based on a Torsion Pendulum

Based on a conventional torsion pendulum,we develop a forced oscillation viscometer with ultra-high viscosity sensitivity of 2×10^（-7）Pa·s working at frequencies near the resonance.The viscosity is achieved by exploiting the phase lag for the angle displacement behind the torque,instead of the resonant curve,i.e.,the variation of angle displacement amplitude versus frequency.The general formula for the measurement of the visco-elasticit.y of complex fluids is also presented.With such precision it is easy to measure tiny change in viscosity result from circumstantial influences.Deionized water and two kinds of NaCl aqueous solutions are chosen to demonstrate the performance of our home-made torsion pendulum-based viscometer.

Structure optimization of connection frames based on frequency sensitivity in macro-micro motion platforms

High-performance connection frames are of great significance for ultra-high acceleration and ultra-precision positioning in macro-micro motion platforms. This paper first takes the connection frame as a research object,builds a finite element model(FEM) of the natural frequency of the frame, and then verifies the correctness of this model. The frequency sensitivity method is then used to perturb the structural parameters of the FEM of the connection frame, and the sensitivities of the first-order natural frequency and mass of the corresponding structural parameters are obtained by calculation and analysis. The design variables are also determined. The natural frequency is used as the optimization objective, and the design parameters and mass of the connection frame are constrained. The structural parameters of the connecting frame are obtained through optimization, and the model is built and verified by experiments. The results show that the first-order natural frequency of the connecting frame is effectively improved by the frequency sensitivity method, avoids resonance between the connecting frame and the voice coil motor, and realizes the lightweight design of the connection frame. This research provides a reliable basis for the stable operation and ultra-precision positioning of ultra-high acceleration macro-motion platforms.

位置探测器与加速度计结合的测振方法

非接触式的振动测量方法具有非侵入和易布置的优点,在实际的工业生产和科研实验中有广泛的应用,但目前的非接触测量方式对测量装置自身受环境冲击振动产生的影响考虑较少。文中提出了一种振动自补偿的低成本的测振方法,采用位置探测器测量振动信号,并利用MEMS加速度计测量测振系统自身振动用于补偿。搭建实验系统对该方法进行了验证。实验结果表明:基于位置探测器的方法能够测量待测物体与测振系统间的振动,而MEMS加速度计能够测量环境引起的测振系统自身振动。经补偿后,环境振动冲击对使用位置探测器方法得到的振动测量结果的影响显著减弱。

复合梁结构的加速度传感器振动特性分析

随着微传感器的发展,谐振式加速度计以稳定性好和检测精度高,成为当前的一个研究热点。谐振器作为加速度计的核心敏感元件,其良好的力学特性对加速度计的工作状况具有重要影响。针对加速度计谐振器设计了一种复合多梁结构,通过控制边界条件对其关键结构参数、加速度计谐振频率和灵敏度影响进行理论分析,结合实际工作环境,运用ANSYS对其模型进行仿真验证,分析关键结构参数对其谐振频率与灵敏度的影响规律,研究结果表明:随梁宽度和梁高度增加,传感器轴向振动固有频率均增加;随梁长度增加,轴向振动固有频率减小;与梁间距无关;此外,随梁宽度和梁厚度增加,传感器灵敏度均降低,其灵敏度与谐振梁长无关,为后续提高加速度计灵敏度提供要点参考。

低低重力卫星KBR和ACC噪声敏感度分析

利用低低卫卫跟踪观测数据所解算的时变重力场是探测分析全球质量变化迁移的重要手段。利用一个月的低低跟踪模式卫星仿真观测数据,分析了星间距离变率误差和加速度计误差对重力场模型解算精度的影响。结果表明:以3×10^(-10)m/s^(2)的加速度计观测误差和5×10^(-7)m/s的距离变率观测误差为基准,当加速度计误差增大一个量级时,截断至120阶次重力异常累积阶误差为3.39mGal;当星间距离变率误差增大一个量级时,截断至120阶次的重力异常累积阶误差为12.39mGal,远大于参考设计指标2mGal。通过比较分析可以说明,星间距离变率误差比加速度计误差对重力场模型精度影响更为敏感,这对低低跟踪体制重力卫星设计、重力卫星下传数据预处理有重要参考意义。

Sensitivity optimization of a monolithic high-shock three-axis piezoresistive accelerometer with single sensing element

There exist several difficulties in the design of monolithic high-shock three-axis accelerometer, such as high g overload, transverse overload and the cross coupling in three dimensions, etc. It is necessary to optimize the sensitivity to improve the performance of the accelerometer. For the monolithic high-shock three-axis accelerometer, the complexity of the sensitivity optimization is that it should consider not only the sensitivity difference between different axes but also the elimination of cross-coupling outputs, together with the natural frequency, structural integrity and high g overload. In this paper, the optimization process for decreasing the difference of the sensitivities between different axes of a monolithic high-shock three-axis piezoresistive accelerometer with single sensing element is established. The optimization is conducted in the condition of 100000 g acceleration by two methods-the method based on the optimization module of ANSYS and the ACO (ant colony optimization) method. The comparison between un-optimized and optimized models proves the efficiency of the optimization methods. In addition, the optimization results show that the ACO method combined with the FEA (finite element analysis) is much more efficient than the method based on the optimization module of ANSYS for the structural optimization problem. And the ACO method can be widely used in the optimization problem of the sensing elements with complicated structure.

核电厂地震加速度计现场标定振动台的研制

针对现有的核电厂地震加速度计的标定方法无法同时涵盖规范规定参数检定要求,也无法实现核电现场就地标定检测的问题,设计了一种基于柔性金属弹片悬挂结构的便携式振动台,分析了振动台的机械结构,给出了振动台动力学方程;依照实际工程应用需求,选取了合适的参数和材料,进行了振动台的三维建模和有限元分析,制造了振动台样机,并对样机进行了测试,测试结果表明,振动台固有频率在1Hz以下,量程可达到1g,横轴灵敏度小于1%,净重在40kg以内,具备便携式特征,满足核电厂地震加速度计的现场标定参数检测的要求。

高灵敏度低频光学加速度计的设计

在结构健康监测、地震监测和航空航天等领域,需要准确测量频率低于10 Hz和振幅小于1 mm的低频微振动,对应的加速度在mg~μg量级。现有商用加速度计的灵敏度多低于0.5 V/g,无法满足要求,故开展了高灵敏度低频光学加速度计的研究。基于加速度计的测量原理,通过理论建模确定了低频加速度计设计相关的技术要求,采用簧片和柔性铰链作为弹性元件,搭配使用单质量块和多质量块,构建了一维、二维和三维弹性机构;基于像散、激光三角法和激光自准直等高精度光学传感原理,设计了高灵敏度的光学传感系统;最终完成了一维、二维和三维低频光学加速度计的设计,并通过实验验证了所设计加速度计的性能,其灵敏度均优于9 V/g,分辨力均优于1 mg,可以用于低频微振动的测量。

高灵敏度ZnO纳米梁谐振式加速度计

针对谐振式加速度计灵敏度较低的问题,设计了一种基于化学气相沉积(CVD)法制备的ZnO纳米线作谐振梁的谐振式加速度计,采用了双谐振梁的差分结构,利用混频检测方式进行谐振梁的激振和拾振。实现了超高灵敏度加速度检测。使用COMSOL Multiphysics软件建立加速度计结构原型,仿真得到谐振梁的谐振频率分别为1926.480 kHz和1926.499 kHz;在±5 gn的量程范围内,单根梁的检测灵敏度为40.218 kHz/gn,差分检测灵敏度达到80.437 kHz/gn;分析了加速度计的温度特性,差分输出模式有效抑制加速度计的零点漂移,灵敏度随温度变化为2.424 Hz/(gn·K^(-1))。

高低温环境对三轴高g值加速度传感器灵敏度变化影响研究

针对高低温环境对高g值加速度传感器灵敏度影响机理不清的问题,通过建立两端固支的敏感单元数学模型,得到了传感器灵敏度与敏感单元纵向应力、横向应力的关系。通过热-力耦合仿真分析得到了传感器灵敏度与温度间的关系,在-40℃~50℃范围内,传感器灵敏度随温度的增加而减小,且在-40℃~20℃范围内灵敏度变化较快,在20℃~50℃范围内灵敏度变化较慢。通过传感器高低温试验得到高低温环境下传感器灵敏度数据,-40℃条件下灵敏度大小为0.523μV/g;50℃条件下灵敏度大小为0.516μV/g。与仿真结果进行对比,验证了温度变化对传感器灵敏度的影响规律,为提升高g值加速度传感器在高低温环境下测量精度具有理论参考意义。

Record-Breaking Frequency of 44 GHz Based on the Higher Order Mode of Surface Acoustic Waves with LiNbO_(3)/SiO_(2)/SiC Heterostructures

Surface acoustic wave (SAW) technology has been extensively explored for wireless communication, sensors, microfluidics, photonics, and quantum information processing. However, due to fabrication issues, the frequencies of SAW devices are typically limited to within a few gigahertz, which severely restricts their applications in 5G communication, precision sensing, photonics, and quantum control. To solve this critical problem, we propose a hybrid strategy that integrates a nanomanufacturing process (i.e., nanolithography) with a LiNbO_(3)/SiO_(2)/SiC heterostructure and successfully achieve a record-breaking frequency of about 44 GHz for SAW devices, in addition to large electromechanical coupling coefficients of up to 15.7%. We perform a theoretical analysis and identify the guided higher order wave modes generated on these slow-on-fast SAW platforms. To demonstrate the superior sensing performance of the proposed ultra-high-frequency SAW platforms, we perform micro-mass sensing and obtain an extremely high sensitivity of approximately 33151.9 MHz·mm2·μg−1, which is about 1011 times higher than that of a conventional quartz crystal microbalance (QCM) and about 4000 times higher than that of a conventional SAW device with a frequency of 978 MHz.

基于精密离心机的三轴硅微谐振加速度计标定方法

为更准确辨识三轴硅微谐振加速度计的误差系数,提高加速度计在飞行器上的加速度矢量测量精度,设计基于精密离心机的加速度计标定方法。分析硅微谐振加速度计的工作原理及误差项,在考虑离心机主要误差源的基础上建立包含零位偏移、标度因数、非正交安装误差、二次项误差与横向灵敏度的硅微谐振加速度计误差模型;设计离心机匀角加速度旋转的三姿态标定方法,在径向轴高g输入的同时,增加角加速度激励,可以更好标定加速度计横向灵敏度;对所提出的标定方法进行仿真,通过最小二乘法完成模型参数辨识。仿真结果表明,参数辨识相对误差可控制在2%以内,二次项系数与横向灵敏度辨识精度均小于1μg。

一种高g值面内加速度传感器的设计与仿真

为了检测侵彻武器冲击硬目标产生的水平方向超高加速度,提出了一种单轴的面内高量程压阻式加速度传感器。该传感器的量程为150000 g_(n),由支撑梁、质量块和4个微梁构成。当给传感器施加轴向加速度时,支撑梁两侧的微梁分别被拉伸和压缩,通过惠斯通全桥实现压阻信号的检测。将加速度传感器的固有频率、最大等效应力以及几何结构参数作为多目标函数,用OSF采样和克里金代理模型对加速度传感器进行优化,得到高谐振频率、高灵敏度和低交叉灵敏度的敏感结构。有限元仿真和电学仿真结果表明,传感器一阶固有频率为0.84 MHz,y轴灵敏度为0.594μV/g_(n),非线性度为3.26%,x轴和z轴的交叉灵敏度均小于1%。

基于几何反弹簧结构的高分辨率MEMS加速度计

为了提高MEMS加速度计分辨率和灵敏度,提出并设计了一种基于几何反弹簧原理的新型MEMS加速度计结构。拟采用静电力将加速度计静态工作点设置在梁低刚度位置来提高灵敏度。首先通过理论计算和有限元仿真,分析了几何反弹簧结构实现准零刚度的原理,并优化了关键几何参数;其次基于免划片SOI工艺完成了MEMS芯片制作;最后搭建了开环测试电路进行测试验证。测试结果表明:施加25 V偏置电压后,加速度计灵敏度从46.3 mV/g提高至51.1 mV/g,线性度为0.99%。验证了静电偏置几何反弹簧结构通过降低刚度系数来提高加速度计的灵敏度的可行性。

三维等灵敏度低耦合弹性机构的设计和优化

振动对仪器和机床的精度都有较大影响,对其进行准确检测和分析,是实现振动有效控制的前提。本研究提出了一种高灵敏度和低耦合三维弹性机构及其参数优化方法。介绍了三维弹性机构的构型,并通过理论建模、参数优化和仿真分析完成了三维弹性机构的设计和优化,最后将该弹性机构与高灵敏度、低耦合传感系统相结合,研制了高性能三维低频加速度计系统,并实测了加速度计系统的性能参数。根据实验结果,使用该弹性机构的三维加速度计的灵敏度优于2.0 V/(m·s^(-2)),耦合误差低于1.5%,以及频率响应范围为1~13 Hz,符合设计要求。因此,本研究所提出的三维弹性机构具有三维等灵敏度和低耦合的特点,可以广泛应用于各种三维加速度计。

高温压电加速度传感器设计与仿真优化

高温压电加速度传感器被广泛应用于振动与冲击测试、故障诊断与监测方面。针对传统压电加速度传感器灵敏度温度漂移过大的问题,该文设计了一种高温压电加速度传感器,该加速度传感器采用正负温度系数的压电元件堆叠设计,以抵消温度变化的影响,进而降低温度漂移。5层YCOB压电元件和1层GdCOB压电元件堆叠构成压缩型压电加速度传感器。应用ANSYS对传感器的性能进行仿真优化,并对提出的降低灵敏度温度漂移的方法有效性进行了仿真验证。结果表明,在常温~800℃全温度范围内,该传感器的灵敏度温度漂移小于±3%,其具有高温稳定性好、测量精度高的优点。

高过载小量程加速度计结构优化与特性分析

在四边固支梁—质量块结构的基础上,优化设计了一种带有微梁的新型四边固支梁压阻式加速度计敏感芯片。通过在结构中引入微梁,有效解决了传统小量程加速度计固有频率与灵敏度相互制约的问题。利用有限元分析软件对优化后的结构进行分析,得到结构的最大应力为2.6 MPa,固有频率为31 kHz,灵敏度为60.9μV/gn,抗过载为10000 gn。与传统高过载小量程加速度计相比较,有效地提高了加速度计的综合性能。

高灵敏度双轴加速度计结构设计与仿真

该文设计了一种具有高灵敏度、低交叉耦合的双轴谐振式微加速度计,使用工型梁作为解耦梁,通过微杠杆机构实现力的放大,结构呈中心对称形式,采用差分检测工作方式。通过仿真分析对结构进行优化并完成加速度计整体结构设计,进而提高加速度计灵敏度,降低交叉耦合。对加速度计结构进行模态分析、灵敏度分析、交叉耦合分析和谐响应分析,结果表明,在±20 g量程范围内,x向标度因数为423.6 Hz/g,y向标度因数为421.8 Hz/g,x向交叉灵敏度为0.000047%,y向交叉灵敏度为0.00078%。仿真结果验证了所设计结构的可行性。