Precision Electronic Compass Design Based On Magnetoresistive Sensor

Electronic compass is a kind of navigation instrument for heading angle measurement based on geomagnetic field.It was widely used in the aspects of weapon collimation,navigation,precise positioning,and underwater target detection.In this paper,a precise electronic compass has been developed based on high-precision magnetoresistive sensors and digital accelerometer,by using the high-performance MCU and Lab VIEW software for data processing and display.In the theoretical research section,the development of electronic compass and the technical differences between domestic and foreign have been introduced in detail.The background and implications for the research have been specified.The theoretical research has established the mathematical model of electronic compass and the algorithm of attitude angle.Performance has been determined by analyzing the relationship between the accuracy of the heading angle and the resolution of magnetoresistive sensor and accelerometer.In the circuit design part,circuits of the electronic compass which including magnetic field signal acquisition circuit,Set/Reset circuit,signal processing circuit,accelerometer peripheral circuit and power management circuit,have been designed based on HMC1021/HMC1022 magnetoresistive sensors and ADXL362 accelerometer.At the same time the power consumption,accuracy,volume factors of the electronic compass have been considered in the circuit design.In the algorithm design part,the functions have been realized including highaccuracy AD conversion,SPI data communication and clock signal output by using the high-performance MCU ADu C845.The data processing have been carried out including zero correction,non-orthogonality correction,tilt compensation and attitude angle solution for the electronic compass system by using Lab VIEW software.Finally,calibration experiments have been finished including non-orthogonality calibration,zero drift calibration and measurement range calibration for electronic compass system,which effectively improved the accuracy of the heading angle measurement.The circuit performance and the measurement accuracy of electronic compass system have been tested.The results showed that the hardware circuit has good performance,the heading angle measurement accuracy is 0.27° and the resolution is 0.03°.In this research,an electronic compass prototype has been developed with the advantages of high precision,small size,low power consumption,which has reached domestic advanced level in measurement accuracy.The electronic compass can be used for precision positioning,military targeting and navigation after continuous optimization and improvement.