Research On Frequency Measurement Circuit And Output Modeling Of Quartz Vibrating Beam Accelerometer

Quartz vibrating beam accelerometer,as one of the key measuring instruments of inertial navigation system,cooperates with gyroscope.According to the characteristics of the mathematical integration algorithm of the inertial navigation system,it can be known that the measurement errors of the accelerometer and the gyroscope itself will accumulate errors with time integration,which will eventually lead to serious deviations of the carrier's heading attitude,motion speed and real-time position.Therefore,reducing the measurement errors of the instrument and improving the accuracy of the instrument are important subjects of the inertial navigation.Accelerometer precision index mainly includes deviation value K,scale factor K,quadratic term coefficientK and random drift.The study includes the double beam difference model,test method,frequency detection method and output modeling method.In this paper,the output model of quartz vibrating beam accelerometer is improved and a new frequency measurement scheme is put forward.Based on the test and data analysis,the causes of output error of accelerometer are analyzed,and the modeling and compensation scheme of output error are put forward.The main work is as follows: 1.Based on the original double-beam difference structure,a weighted double-beam difference model is proposed,and two calculation methods of model equations and related parameters are given.Through the calculation of experimental data,the results of the two models are compared and analyzed with those of the original two-beam difference model.It is concluded that the stability of the two models is improved without changing the repeatability of deviation value K and scale factor K.The value K and scale factor K can be adjusted,and model 2 improves linearity.2.The paper evaluates the advantages and disadvantages of four-position roll method and eight-position roll method in the measurement of quartz vibrating beam accelerometer,and draws a conclusion that the four-position roll method has a better measurement effect.It proves the accuracy of the four-position roll method which has a guiding significance in the measurement of instrument,and the work has a guiding significance for the current measurement.3.The advantages and disadvantages of the current equipment are analyzed.Considering the problems of miniaturization,low cost,high precision and data continuity of future instruments,a frequency acquisition system based on FPGA is proposed.The digital circuit is designed.The synchronous frequency measurement algorithm of double counter and the software of host computer are compiled.The two measurement experiments designed verify that the frequency measurement circuit basically meets the requirements of the subject.It lays a foundation for the follow-up development of high-precision frequency measurement system at strategic level.4.A temperature model based on cubic spline interpolation fitting is established by studying the process of output changing with temperature,and a temperature-time drift model based on polynomial fitting is established by analyzing the process of output changing with time.The experimental data are compensated based on output compensation model which is proposed in the paper.Compared with the previous results,the repeatability of K at each temperature point is reduced by about 50% and the range of K variation is reduced by about 50% in the whole temperature range.Combining with the work of the weighted double-beam difference model,the stability is improved about three times.The work has certain engineering value.Combining with the current research hotspots and problems,the paper carries out the above research content,and draws conclusions through analysis and research.The rigorous work through experiments has proved the effectiveness of the work,which is helpful to the further study.