Integration System of Phase-Locked Loop Imaging and Dots Centroid Tracking Methods for Tire Deformation Measurement during Rolling

This study develops an image measurement system that accurately measures rotating tires’ deformed shape. Noncontact image measurement presents challenges such as difficulty in achieving a high sampling frequency and high pixel count, and achieving high resolution in feature point tracking as a subset in image processing because of the curvature, expansion, and contraction of the tire sidewall. The shape of the sidewall affects the mechanical properties of the tire, and the deformation shape during actual operation provides important information for tire design. In this study, a system integrating phase-locked loop imaging, dot centroid tracking (DCT), and stereo methods is used to achieve high-resolution measurements of tire deformation shapes. In particular, the DCT method typically improves the accuracy of tracking by setting the markers in black and the background in white and ignoring imaging noise from the background with white halation depending on the amount of light. 3D measurements under static conditions were conducted to validate the proposed system. Consequently, the system was confirmed to be capable of capturing the differences in the sidewall deformation depending on the test conditions, and the validity of the system was confirmed.