Measurement of Cross-Sectional Area of a Deformed Rotating Tire by the Sampling Moiré System

Abstract

We developed a system that can measure the cross-sectional area of a deformed rotating tire by the sampling moiré method. The cross-sectional area is an essential factor in tire cavity resonance theory. Fringe patterns on the tire surface are projected by a projector and recorded by a camera, and patterns on two flat planes are recorded as reference patterns at different known positions along the depth direction to calibrate the deformation. The shape of the deformed rotating tire is obtained from the phase differences between the planes and the tire surface. Also, the noise is suppressed by using an image averaged from multiple fringe images. This measurement method is the basis of a method for checking the degree of deformation caused by roller jacks and determining the cross-sectional area of the whole tire. Finally, the ratio of the cross-sectional area of the loaded tire to that of unloaded tire is obtained, and the ratio at the contact surface is as good as that obtained using a three-dimensional laser scanner.