Research On The Measurement Of Azimuth Based On Geomagnetic Field

With the latest and most advanced technology of sensors and microelectronics, electronic compass provides a cost-effective, highly reliable solution for a variety of applications that require precise navigation. Electronic compass has important value both in military and civilian areas, and it also has enormous market demand and potentiality. Thus a number of manufacturers, research institutions and universities, both domestic and overseas, have been engaged in developing electronic compass.The development of electronic compass is related to various fields, e.g. geomagnetic field detecting, signal conditioning, analog-to-digital converting, digital signal processing, solutions to the carrier's tilt and heading, data display and transmission, etc. It needs the supports of theoretical research and experiment, and that is the basis and aim of this thesis.To ensure and enhance the performance of the electronic compass, this thesis has mainly researched and discussed the following issues.⑴Design of sampling process and digital filtering algorithm, for the acquisition of reliable geomagnetic and gravity data.⑵Solutions to the carrier's tilt and heading according to geomagnetic and gravity data, and the use of CORDIC (Coordinate Rotation Digital Computer) algorithm to improve the efficiency of calculation.⑶Calibration of the sensors with modified 12-attitude method.⑷Experiment of the calibration method for magnetic deviation that based on ellipse hypothesis.⑸Analysis of the HMR3000's serial communication protocol, which is modeled after NMEA0183 standard, and realization of the compatible serial communication function in the electronic compass prototype.Finally, the comparative test is performed between HMR3000 and the electronic compass prototype with the achievements of this thesis. Experiment results have demonstrated that with the tilt accuracy better than 1°in±60°tilt range, heading accuracy better than 1.5°in horizontal plane, and a complete function of serial communication, the prototype is fairly usable.