Tyre Footprint Geometric Form Reconstruction by Fibre-Optic Sensor’s Data in the Vehicle Weight-in-Motion Estimation Problem

Abstract

The problem of measuring road vehicle’s weight-in-motion (WIM) is important for overload enforcement, road maintenance planning and cargo fleet managing, control of the legal use of the transport infrastructure, road surface protection from the early destruction and for the safety on the roads. The fibre-optic sensors (FOS) functionality is based on the changes in the transparency of the optical cable due to the deformation of the optical fibre under the weight of the crossing vehicle. It is necessary for WIM measurements to estimate the impact area of a wheel on the working surface of the sensor called tyre footprint. Recorded signals from a truck passing over a group of FOS with various speeds and known weight are used as an input data. The results of the several laboratory and field experiments with FOS, e.g. load characteristics according to the temperature, contact surface width and loading speed impact, are provided here. The method of decomposition of input signal into symmetric and asymmetric components provides the chance to approximate geometric size of tyre surface footprint as well as calculate the weight on each wheel separately. The examples of the estimation of a truck tyre surface footprint using FOS signals, some sources of errors and limitations of possible application for WIM are discussed in this article.