Research On Inertial Navigation Track Detection Method Based On Tag Positioning

In view of track irregularity, a non-contact dynamic inertial navigation track detetion method based on tag positioning is investigated. The track state detection method is inertial reference method and chord measurement method, inertial reference measurement method can reflect the state of the track.Track detection device is mainly large track inspection car and static testing device, the former is high detection precision and high cost and low case detection effect badly; the latter is static detection and can not accurately reflect the track state.This paper analyzes the existing track detection method and proposed inertial navigation track detection method based on tag positioning for the subway and light rail track state detection.The detection method is mainly based on the strapdown inertial navigation technology and measure the track irregulary and settlement, the tag positioning correcte position error of the track irregulary. Track irregulary detection method applys inertil navigation technology: three accelerateons are measured with accelerometers; the angular velocity information of the three directions of the space is measured by the gyroscope, and the attitude matrix is updated by the attitude matrix, then the accelerations on three axis are transdfered into the geographyc coordinate; finally, the position of the objective can be obtained in the space by integrating the transformed accelerations. The track line deformation condition is gained from comparative analysis of the data which acquired in different periods but on the same reference point of measurement.In this paper, we study the real-time updating algorithm of atrapdown attitude matrix and the processing of intertial measurement unit. Using quaternions to solve the attitude matrix and update navigation frame of the inertial navigation system. Design of a digital integrator, we can obtain the spatial displacement of the track inspection vehicle information by integrating the transformed accelerations. Due to the low-frequency component of the acceleration signal will cause the integrator saturation problem, Hilbert Huang Transform(HHT) is used to filter it, it can effectively remove the low-frequency component of the acceleration signal by EMD method.In this paper, we design the track state detecting carriers —— Portable track inspection vehicle. The vehicle is composed of six modules, each module is equipped with a quick disassembly device, which is connected with the body, which is firm and stable after the rapid interface assembled. Track inspection vehicle inspection speed is 20km/h which meet the dynamic test requirements. Tag positioning technology is based on the principle of radio frequency, which reading for the location of the information of the electronic tags and access to positioning information to achieve accurate positioning of the target. RFID reader and tag are respectively installed in the portable track inspection car and sleeper. The RFID reader and the passive RFID tag read and write distance is 20 cm, the reader’s working frequency is 125 KHz, the installation distance between tags is 1km.After a series of tests, the detection system shows that the strapdown inertial technology is feasible in the track state detection. It can effectively remove the low-frequency component of the acceleration signal by EMD method. The portable track inspection car running smoothly, accurate operation, stable performance, fast track down. RFID positioning system accurately reflects the mileage information. After checking the mileage, it can reflect the position information of the track irregularity.