A methodology for the measurement of track geometry based on computer vision and inertial sensors

Abstract: This document describes the theory used for the calculation of track geometric irregularities on a Track Geometry Measuring System (TGMS) to be installed in railway vehicles. The TGMS includes a computer for data acquisition and process, a set of sensors including an inertial measuring unit (IMU, 3D gyroscope and 3D accelerometer), two video cameras and an encoder. The main features of the proposed system are: 1. It is capable to measure track alignment, vertical profile, cross-level, gauge, twist and rail-head profile using non-contact technology. 2. It can be installed in line railway vehicles. It is compact and low cost. Provided that the equipment sees the rail heads when the vehicle is moving, it can be installed in any body of the vehicle: at the wheelsets level, above primary suspension (bogie frame) or above the secondary suspension (car body).