Application and Improvement of the TRRL (Transport and Road Research Laboratory) High-Speed Laser Profilometer Algorithm with Sensor Fusion*

Road roughness detection on highway networks is considered to be vital in order to ensure driving comfort and safety. High-speed profilometers are developed in order to be able to monitor road roughness on highways without affecting the normal traffic flow. This paper focuses on the improvement and the implementation of TRRL-type high-speed laser profilometers. The original design includes 4 laser sensors which are placed along a trailer of 5m length to be towed by a vehicle. As the trailer moves forward, the leading laser sensor measures the road elevation and it is referenced by the other sensors so that the system does not require an inertial sensor for referencing. In the presented work, the original TRRL design is made more compact in order to allow faster operating speeds. The error analysis seen in the original work is extended with the changed geometric design. It is observed that the factor that affects the measurement accuracy the most is surface texture due to its randomness. Therefore the paper proposes a new method which minimizes the texture-caused errors by modelling them with quadratic functions. The performance of the presented profilometer is evaluated by conducting experiments on a road with a known true profile. The accuracy and the repeatability of the system show that the presented profilometer can be used for measuring true profiles with some further improvement.