Tyre condition analysis

Abstract

The condition of a tyre () on a wheel () is assessed while the wheel () is mounted on a vehicle () and while the vehicle () is moving. As the vehicle () moves, the tyre () rotates and moves longitudinally along a path of movement. An imaging device () captures images of a plurality of different portions () of the periphery of the tyre (), which has tread portions () separated by tread gaps (), whilst the tyre () revolves. While the images are being captured, longitudinally spaced flash units (F, F, F, F) are activated to illuminate portions () of the periphery of the tyre (). The flash units (F, F, F, F) are positioned to one side of the path of movement of the tyre () and direct light at an acute angle to the path of movement of the tyre () so that the light causes shadows to be cast in the tread gaps () between tread portions (). Each flash unit (F, F, F, F) causes a series of flashes of light to be produced when the flash unit (F, F, F, F) is activated, each flash of light in the series being separated from the next flash of light in the series by an interval. For any flash units (F, F, F, F) which are activated at the same time and illuminate overlapping portions of the periphery of tyre (), the respective series of flashes of light are out of phase so that the flashes of light from one flash unit (F, F, F, F) are emitted in the intervals between the flashes of light from the or each other flash unit (F, F, F, F). The images are analysed by data processing apparatus () to determine the extent of shadows in the tread gaps () so as to provide an indication of the depth of the tread gaps ().