Research On Data Acquisition And Calibration Technology Of MEMS Strapdown Inertial Navigation System Based On ARM

Micro-inertial technology is a key technology in navigation science which develops rapidly in recent years.The strapdown inertial navigation system based on MEMS is widely used in navigation with low or medium accuracy,which has been highly valued by major institutions,universities,national defense and other fields at home and abroad.Recently,the accuracy of the MEMS inertial measurement unit is much lower than that of the traditional inertial system,so it is of great practical significance to study how to improve the measurement accuracy of the MEMS inertial measurement unit.The The aim of the project is basically to build a complete hardware platform of MEMS strapdown inertial navigation system,The paper particularly studies the data acquisition method of MEMS inertial measurement unit and the calibration noise reduction technology of MEMS inertial device,so as to improve the measurement accuracy of inertial measurement unit.Firstly,based on TI's OMAPL138(DSP+ARM dual-core)processor,the MEMS Strapdown Inertial Navagation System schematic and PCB board were designed.Processor OMAPL138 and inertial measurement unit ADIS16488 A constitute a master-slave structure.The paper also includes the designs of data acquisition circuit,multi-voltage output power supply circuit,RS422 circuit for communication with host computer,DDR2,Nand Flash,SD card storage circuit and download configuration circuit.At the same time,a high-speed 6-layer PCB board was designed and the physical board was completed.The board has realized a series of functions for the ADIS16488 A such as data acquisition,data calibration,navigation alignment and calculation.Secondly,use the designed hardware to be the carrier,the data acquisition program of the processor and ADIS16488 A is written in C language use the method of SPI communication based on the ARM end of OMAPL138.The program can realize the data acquisition of the ADIS16488 A three-axis gyroscope,three-axis accelerometer,three-axis magnetometer,barometer,thermometer,and sent them to the host computer through the serial port to realize communication with the host computer.The data of the corresponding sensor can be collected according to the user's needs,and the sampling frequency can be set to meet the needs of different occasions.Finally,write the calibration program in C language to achieve online real time calibration.Thirdly,processe the collected data.After complete the error analysis of MEMS gyroscope and accelerometer,the error model is established.Then use the discrete calibration angular rate rotation and six-position method to complete the calibration of MEMS gyroscope and accelerometer.Use FIR low-pass filter to remove the high-frequency noise of gyroscope.The time series analysis method is used to establish the ARMA model for the static data of the gyroscope,and the random noise of the MEMS gyroscope is reduced by the Kalman filtering method.Finally,complete the overall experimental debugging of the project.The hardware board function test,write a Labview program to complete the data synchronization admission experiment,calibration experiment and noise reduction experiment have been carried out successively.It is verified by experiments that the function of the board is normal and the calibration effect is obvious.After the FIR low-pass filtering,the variance of the MEMS gyroscope is reduced by 2 orders of magnitude,and the Kalman filter variance is reduced by 3 orders of magnitude,after combined filtering,the variance is reduced by 5 orders of magnitude.