Specialized navigation system for rail track diagnostics

All parameters of the railway track are calculated as a function of the distance covered by the track measurement car. Hence the requirements to this path measurement accuracy are very high. Track geometry measurement requires rather accurate positioning of the revealed track defects. Odometer is the main tool for measuring the path traveled by the car. Using odometer as a sole measurement instrument does not provide accurate localization of the revealed defects due to its errors, which depend on car speed, wheel slipping, and weather conditions and can be as high as 5 m per 1 km. The most complete and efficient approach to improving the accuracy of measurement of the traveled distance is integration of odometer with inertial navigation system, GPS and special navigation markers along the distance. Results of IONS (integrated orientation and navigation system) development for rail transportation are given.