Research On The Intelligent Monitoring Technology For Vehicular Safety Based On MEMS-INS/GPS/magnetometer Integrated System

With the increase in car ownership and number of buildings in downtown in China, the Intelligent Traffic System is becoming an important part of information construction, in which the vehicle safety monitoring is an important issue. Owing to high price, the existing vehicle safety monitoring systems are only equipped with highly special vehicles and highly integrated with the automobile internal signal system. For market of low grade vehicles, it is imperative to research on a inexpensive and independent vehicle safety monitoring system.This paper presents a vehicle safety monitoring scheme based on MEMS-INS / GPS /magnetometer integrated navigation, aims to solve the problems which in the existing vehicle safety monitoring system. By combining the information from MEMS,GPS and magneticmeters, it’s independent to acquire vehicle information for monitoring crash,speeding, unwonted attitude, integrity of the system, which is able to improve the precision,continuity and reliability of the system。The vehicle safety monitoring system can monitor the vehicle state in real time, without access to the vehicle state information from inside signal system. The main contents are as follows:(1)This paper designed a hardware platform for integrated attitude determination based on MEMS accelerometers, gyroscopes and magnetometers, and a data acquisition software using VC++ software development platform. In order to improve the precision of the system,a scheme of angular rate and six-positioned static tests was carried out. And MEMS-INS was calibrated by a 7-day calibrating test. In the analysis of magnetometer errors,both soft and hard iron interferences were analyzed, and a compensating method for magnetometers based on an assumed ellipse was put forward. Its effectiveness was proved by analyzing real data collected by 8-positioned method.(2)According to studying the principles of SINS and Magnetometer, a plan for integrated attitude determination based on MEMS-INS/Magnetometer was designed. Roll and Pitch were determined by highly precise MEMS accelerometers, and Yaw was obtained with the aligned magnetometers. Confusing the data of MEMS-INS and magnetometers, the Kalman filter was able to estimate the best attitudes of integrated attitude system, which offered highly precise attitude information for vehicle safety monitoring system. While GPS working standalone, GPS signal was easily disturbed by noise, so there would be large errors in GPS positioning and speeding and it would be a problem for vehicle safety monitoring. As for this,a loosely coupled positioning scheme based on MEMS-INS/GPS/Magnetometer was proposed. A integrating system was implemented with close-looped Kalman filter by confusing GPS and magnetometers to assist MEMS-INS. It was capable of offering highly precise attitude, speed, position to vehicle safety monitoring system .(3)According to the vehicle information provided by integrated system, various intelligent monitoring strateges were studied including tests based on collision and speeding and integrity monitoring methods, in which the snapshot RAIM algorithm was specially analyzed and studied. An integrity monitoring algorithm based on kalman filtering residuals was designed, which was able to monitoring faults of MEMS-INS, GPS and magnetometers.By means of analyzing vehicle data collected outdoor, it was validated that this algorithm could detect faults existing in the system and give alarm to users in time.