Research On Digital Smart Three-component Force Balance Accelerometer

With the development of digital signal processing and network technology,vibration sensor must have higher accuracy and reliability. Digital intelligentaccelerometer can perform data acquisition, control calculation, triggerjudgment and data transmission. It has the characteristic of high precisionand low power consumption. On the basis of original analog force balanceaccelerometer, the intelligent digital output accelerometer is studied toprovide technical support for the strong motion observation. This dissertationmainly includes the following work:1This paper presents a scheme of digital smart accelerometer combinedwith high-precision digital acquisition system and control system. Thecharacteristics of the scheme are using high-precision24-bit A/D converter,high-speed signal processor as the controller. The accelerometers have largedynamic range, low power consumption and small size features.2This paper analyzes the operating principle of force balanceaccelerometer. Under the basis of theoretical analysis, the circuit design ofdigital integrated demodulation and sine wave oscillator is performed and theimprovement is experimental tested.3The accelerometer magnetic circuit is analyzed with permeance methodand finite element method. Measurement data show that both methods canmeet the requirement of the sensor magnetic circuit design, but finite elementanalysis method is more accurate.4The relationship between drift voltage of the accelerometer and theambient temperature is studied using the least squares method through thetemperature experimental test. Error brought up by using different curvefitting methods is tested. The temperature compensation circuit is designedfor the accelerometer. This paper points out that quadratic and cubic curvefitting for temperature compensation can reduce the temperature voltage drift.Although the high curve fitting is able to further minimize the drift, whichalso increase the computational complexity and affect the efficiency ofsystem operation.5The prototype of intelligent tri-axial force balance accelerometer isdeveloped. Transfer function of digital accelerometer is studied by analyzingits working principle. Under the conditions of limited hardware resources,the method for optimize the TCP/IP protocol is studied, which can be used inthe embedded system of the intelligent sensor for the data transmission andweb-based interactive control. Embedded file system based on CF card isdesigned for data collection and storage. Strong motion records trigger filterare designed for the accelerometer, and its performance is tested.6In this paper, the transfer function and characteristic parameters areanalyzed. Linear phase and minimum phase digital filters used in digitalprocession are introduced which have different features and different usage scope. Features of accelerometer are tested by laser interferometry methodand self calibration method. The transfer function fitting analysis isperformed by experimental data using least squares fitting method. Thecross-axis sensitivity and misalignment angle are measured and analyzed,which would affect the accelerometer performance.7The accelerometer calibration system based on virtual instrument isdesigned for testing the factor of sensor. The differences arising from usingdifferent calibration method are comparative analyzed to make it clear theapplication scope of the methods. The noise characteristics and dynamicrange of digital accelerometer are analyzed.8Digital tri-axial accelerometer is tested in detail, and experimental datashows that its performance achieve the expected the design requirements.