Multi-information fusion method of INS/Odometer/GNSS and its application in railway surveying and mapping

According to the demand for accurate mapping the railway infrastructure based on the inertial technology, a multi-information fusion scheme is put forward which can provide high-precision attitude and position as the surveying and mapping references. The characteristics of high-speed train motion and the heading error's observability of the inertial/odometer integrated navigation system are analyzed, which show that the main factors that affect the measurement accuracy are the Y-gyro drift and the heading accuracy. A multi-information fusion scheme is designed based on the forward/reverse filtering/smoothing track fusion, and the concept of "vector" is introduced to judge the relative positioning precision. Simulation and test results show that the proposed scheme can significantly increases the precisions of attitude and position references in railway surveying and mapping and realize high-precision measurement and positioning by low- and mid-precision inertial devices, in which the relative positioning error can be reduced to <0.3 mm (300 m versine vector) even when the gyro's constant drift is increased by 0.2 (°)/h.