Laser-Aided INS and Odometer Navigation System for Subway Track Irregularity Measurement

Abstract

Track irregularity is one of the most important factors in the regular maintenance and overhaul work needed to determine the state of a railway for safe operation. In this paper, a mobile approach to the measurement of subway track irregularity is proposed. A high-precision three-dimensional (3D) curve of railway track was surveyed by a track trolley equipped with a laser-aided inertial navigation system (INS)/odometer navigation system. Models for measuring the alignment, vertical, cant, and twist irregularities were established. These four types of irregularities were estimated using the 3D track curve. To solve the problem of inherent drift of the INS/odometer system, a laser scanner on the trolley was used to obtain observations of control points along the rail track for position updates. Measurements of real track irregularities were conducted to validate the proposed method. The experimental results indicate that this approach has good repeatability. The accuracy of track-irregularity measurements meets the technical requirements of the Shenzhen Metro in China.