Evaluation of aspects affecting measurement of three-axis accelerometers

In order to set integrated procedures involving geotechnical and structural aspects finalized to buildings diagnostics, uncertainty aspects are discussed concerning three-axis accelerometers and inclinometers for a distributed sensor network. This network allows to operate in a selective manner, preferring the most critical situations. To this aim, the main aspects affecting the measurement uncertainty of sensors to be used for building diagnostic should be known. As the firstly step of the uncertainty evaluation procedure, we focused on the calibration of sensors used for the task. The requirement of low cost and complexity of sensors and test benches was considered. Experimental results show that satisfactory calibration accuracy could be achieved, also for the low frequency range, 0–10 Hz. Systematic errors are minimized and main parameters affecting uncertainty are identified, such as: the motion positioning of the accelerometer with respect to the vertical axis, the imposed motion law, the parameter used as the reference and, finally, the real radial positioning of the sensor. Requirements to be satisfied by the sensor are also analysed.     

Design of a Triaxial Piezoelectric Accelerometer

A monolithic MEMS triaxial accelerometer based on piezoelectric lead zirconate titanate (PZT) thin films with highly symmetric quad-beams and a seismic mass, has been designed and simulated. Theoretical and numerical models for this structure are presented. The dynamic response and the trade-off between several design considerations are discussed. Static and modal simulations with FEM (Finite Element Method) simulator have been performed to analyze the mechanical response. It shows that the sensitivities of the three axes (X, Y, Z) are respectively 27, 27, and 29 mv/g, and there is almost no transverse sensitivity for the accelerometer. Also, the device is expected to have good temperature performance.     

引信用微压阻式加速度传感器系统设计

所设计的微机械压阻式加速度传感器系统,能同时用于导弹引信的安全系统和发火控制系统;系统包括传感器、信号处理电路和自检测系统;以国内现有的加工水平为依据,通过优化设计得到传感器的结构参数,并对各项指标进行了仿真计算,在满足性能指标的前提下,保证器件良好的可加工性。     

Simulation analysis of directivity and optimization of the array of the AlN thin film PMUT array

The relatively low piezoelectric constant of the aluminum nitride piezoelectric film limits the development and application of the piezoelectric micro-machined ultrasonic transducer based on the aluminum nitride. Therefore, the directivity of the piezoelectric micro-machined ultrasonic transducer array is studied for this problem. First, the far-field sound pressure and normalized directivity function of the transducer array are calculated according to the Rayleigh principle. Furthermore, the effects of array element radius, array element spacing, array element number and operating frequency on the beam width, direction sharpness angle and sidelobe level of the array are analyzed, and the transducer array is optimized. Finally, based on the optimization results, area and filling efficiency, the final structure size of the transducer array is determined and the sound pressure distribution visually simulated. The results show that the optimized transducer array has an ideal sound pressure distribution, good directivity and sharp main lobe. The-3dB beamwidth of the main lobe is about 9 ° and the sidelobe level is about 0.228.     

Gravimetry based on the method of inertial navigation

A method of spatial gravimetry based on expansion of the functional properties of a three-component inertial navigation system is considered. __________ Translated from Izmeritel’naya Tekhnika, No. 2, pp. 7–9, February, 2006.     

Measurement of linear accelerations using optical radiation

An expression for the relativistic frequency shift in a two-channel optical accelerometer is obtained and it is shown that, from the standpoint of applications, it is functionally analogous to a mechanical accelerometer, i.e., it is a gauge of the apparent acceleration.Translated from Izmeritelnaya Tekhnika, No. 10, pp. 31–32, October, 2004.     

Robust optimization using a gradient index: MEMS applications

This paper discusses a simple and effective robust optimization formulation and illustrates its application to MicroElectroMechanical Systems (MEMS) devices. The proposed formulation improves robustness of the objective function by minimizing a gradient index (GI), defined as a function of gradients of performance functions with respect to uncertain variables. The level of constraint feasibility is also enhanced by adding a term determined by a constraint value and the gradient index. In the robust optimal design procedure, a deterministic optimization for performance improvement is followed by a sensitivity analysis with respect to uncertainties such as MEMS fabrication errors and changes of material properties. During the process of the deterministic optimization and sensitivity analysis, dominant performances and critical uncertain variables are identified to define the GI. Our approach for robust design requires no statistical information on the uncertainties and yet achieves robustness effectively. Two MEMS application examples including a micro accelerometer and a resonant-type micro probe are presented.     

电容式硅微加速度计在小型飞行器上的应用

低成本传感器的应用是小型飞行器迅速发展的现实要求,将MEMS传感器技术结合飞行器应用是一个全新的前沿发展方向;对电容式硅微加速度计在小型飞行器上的应用进行了研究,提出此类加速度计存在输出不完全的问题,创新性的给出重力补偿解决方法;通过分析加速度计的误差,并做静态实验以修正,推导了加速度计的工作函数;最后由振动实验,证明在小机动飞行状况下,电容式硅微加速度计能够满足小型飞行器的控制要求.     

三轴加速度计ADXL330的特点及其应用

ADXL330是美国模拟器件公司推出的完整的三轴加速度计,可以静态或者动态测量物体的加速度,测量范围是±2g.介绍了ADXL330的主要特点及其在组合导航系统中的应用.     

一种硅梁谐振加速度计结构设计与模拟分析

为了提高谐振加速度计的灵敏度以及稳定性,提出一种基于微杠杆力学放大机构的硅梁谐振式加速度计结构,并对其进行了有限元模拟分析。该加速度计由两个静电激励电容检测的硅谐振梁组成差分输出,采用硅深刻蚀以及硅玻璃阳极键合等体硅工艺制作。模拟结果表明新结构提高了加速度计灵敏度,有效改善了交叉灵敏度、线性度、温度稳定性等。