Research On Multiple-channel Fast Frequency Measurement And On-line Temperature Compensation Method For Micromechanical Silicon Oscillating Accelerometer

Considering the advantages of Micromechanical Silicon Oscillating Accelerometer(SOA),such as high precision,small size,and direct frequency output,the SOA has significant values and promising prospects in both military and civil applications.In this paper,multiple-channel fast frequency measurement technique and temperature compensation method are researched for the SOAs in MIMU based on application requirements,which can detect the accurate acceleration parameters on-line.This paper mainly addresses following issues:1.This article has established the dynamic equivalent model and introduced detection principle according to the SOA structure designed in the research projects' group.Then several methods of frequency measurement methods and measurement errors have been analyzed in comparison.Combined with the practical demands of SOA applications,this paper has adopted the multi-period pulse synchronization counting method and the phase-shift eight-clock counting method for the detection of frequency.2.The paper has designed the algorithm of the multi-period pulse synchronization counting method and the phase-shift multiple-clock counting method with Verilog HDL based on the symmetrical differential structure of the SOA,which realized double-channel synchronous frequency measurement and real-time difference calculation.In addition,the paper has set varied sampling rates to realize high-speed sampling for the requirements of data update rate in system.The theoretical analysis proved that the max error of the phase-shift eight-clock counting method was decreased by eight times compared with the multi-period pulse synchronization counting method,and the max error of the former could achieve 0.075mHz,while the latter has less resource occupation and better real-time performance.3.The paper has designed and debugged the six-channel frequency measurement circuit for SOA in MIMU.On this basis,this paper has tested measurement errors of the multi-period pulse synchronization counting method and the phase-shift eight-clock counting method.Experimental results have shown that the latter average frequency measurement error was superior to the former obviously and it could achieve 0.03mHz.high-speed sampling results have shown that sampling rates could achieve 100Hz and the measurement errors is in line with the theoretical analysis.Then some performances of the accelerometer have been tested by the circuit to verify the correctness and the validity of the software and hardware.4.This article has analyzed the effect of temperature on the resonant frequency according to the working principle and material characteristic in the SOAs.On this basis,this paper has proposed an on-line temperature compensation method modeled by the resonant frequency and has developed temperature compensation algorithm on FPGA with Verilog HDL.Experimental results have shown that the on-line temperature compensation under the room temperature and within the full temperature range can compensate the bias and increase the bias stability of the SOA,which has good prospects in engineering applications.Totally,this article has developed a multiple-channel frequency fast measurement circuit for detection of acceleration parameters of the SOA in MIMU and has designed an on-line temperature compensation modeling method,which laid a foundation for further study of SOA applications.