Integration of Multiple Sensors for Noncontact Rail Profile Measurement and Inspection

Abstract

Rail profile measurement is one of the most critical tasks for track quality inspection to ensure the safe operation of track systems. In modern railway systems, laser triangulation sensors have been widely adopted in onboard measuring units to carry out 2-D rail profile measurement due to their robustness and truly noncontact properties. However, existing solutions limit the degrees of freedom of the laser sensor and thus cannot provide full coverage of the rail profile due to the “shadowing effect” of triangulation sensors. Incomplete profiles limit the performance of wear assessment hence more detailed inspections still rely on contact-based tools operated by humans. These processes are time-consuming and incompatible with the ever-shortening maintenance windows available in modern railway systems. Benefiting from the miniaturization of sensing technology and improving processors, multisensing systems combine the strengths of different sensors. This article presents a new solution for a laser-based multisensing system for noncontact rail profile measurement and wear inspection. The addition of an inertial measurement unit (IMU) and a camera module allows portable rail profile measurement without “blind spots.” Optimized iterative closest point (ICP) registration is then applied to generate a complete representation of the rail profile. Experimental results demonstrate that the proposed system can provide accurate and efficient rail profile measurement, and could potentially replace conventional contact-based inspection tools.