The Research On High Precision Accelerometer Signal Acquisition And Processing Of SINS

Accelerometer is one of the core components of strapdown inertial navigation system.It is mainly used to sensitize the moving information of carrier along a certain direction.The signal quality of accelerometer can directly affect the performance of SINS.Therefore,how to obtain more accurate accelerometer information has become one of the key issues in inertial navigation research.Due to the complexity of the working environment of SINS,external noise interference is unavoidable in the process of signal acquisition and transmission.How to remove the noise component in the signal and extract useful information is very important in the process of data processing of SINS.Therefore,based on the application requirements of inertial navigation system,a high-precision accelerometer signal acquisition system is designed and optimized,and a new Wavelet Threshold Algorithm is used to filter and denoise the signal,thus achieving high-precision signal acquisition.The research work of this paper is mainly divided into the following aspects:Firstly,according to the system design requirements and technical indicators,by analyzing and comparing the research status of accelerometer signal acquisition circuit at home and abroad,the overall design scheme of data acquisition system based on "I-V+AD " is proposed.The accelerometer signal acquisition circuit is designed and completed,and the circuit structure is optimized.The circuit principle of each part of the hardware design is described,especially the optimal design of the reference voltage circuit and the influence of the heating of the power chip on the circuit.The software design including AD initialization configuration,data reading and serial output is completed by the modular design of the FPGA program.Then,based on the analysis of the characteristics of accelerometer signal noise,the system noise is studied in the wavelet domain.The theoretical effect of Wavelet Denoising is verified by comparing the traditional Fourier Filter and Wavelet Filter through simulation analysis.On this basis,the effects of different threshold estimation methods and threshold processing functions on Wavelet Denoising are discussed,and a new Wavelet Threshold Algorithm is proposed.Through simulation and data analysis,the denoising effect of the new Wavelet Threshold Algorithm is better than that of the traditional denoising method.On this basis,the implementation of the new Wavelet Threshold Algorithm on the FPGA is studied in this paper.According to the algorithm,the key modules such as wavelet decomposition and reconstruction,signal continuation and wavelet threshold processing are designed.The design and implementation process of the new Wavelet Threshold Algorithm on the FPGA are introduced by combining the timing simulation diagram of each module in ModelSim environment.The simulation results show that the implementation of the new Wavelet Algorithm based on FPGA can achieve better de-noising effect and meet the real-time requirements of signal processing.Finally,after circuit debugging and software algorithm simulation,the acquisition accuracy,linearity and stability of the acquisition system are tested in detail.The experimental results show that the new Wavelet Threshold Algorithm can effectively improve the performance of data acquisition system.The effective bit of ADC can reach 22.4 bits in no-load condition,the effective resolution of ADC can reach 18.5 bits in load condition,and the effective resolution of acceleration can reach 20 ?g.The system performance index meets the design requirements.In addition,in view of the influence of temperature on the output of quartz accelerometer,the differential method is used to compensate the temperature error of accelerometer.