Design And Realization Of Attitude Measurement System Based On Magnetoresistive Sensor

Geomagnetic navigation which takes advantage of geomagnetic characteristic quantity to navigate is a kind of autonomous navigation technology .It possesses lots of advantages, such as high precision , good concealing, strong anti-interference ability, which satisfy the future navigation requires of aircraft, submarine, missile, etc, and the extensive use in civil field. Heading and attitude are the most important parameters in the navigation system, which directly impact performance of navigation system. Based on analysis of geomagnetic navigation, a series of designs and experiments were carried out in the paper.First, development situation and theory of geomagnetic navigation were discussed , based on which, a scheme of getting the attitude angles from measuring geomagnetic field was put forward: 3-axis geomagnetic components were measured by magnetoresistive sensors and the pitch and roll angles were measured by accelerometer, to calculate out the heading angle by matrix transform. Software and hardware of the system were designed and realized. On the hardware part, sensors and system-chip were described, the power supply circuit, signal conditioning circuit, set/reset circuit, accelerometer circuit, serial communication circuit and LCD circuit were designed. Real-time attitude measurement, result display and transmission were realized. On the software part, via data collection, filtering and calculation heading angle was displayed and transmitted. Median filter algorithm was applied to signal processing and stable heading angle was obtained. In addition, the influence of nonorthogonal error, sensors error and magnetic deviation to heading angle were discussed. Especially, compensation test was made using the least square method.The results showed that the heading angle stability was about 0.7°and the heading error was about 1°after the compensation, reach the due acquirement basically.