Patent ID: 7864309

Claim:
A method of determining alignment characteristics of a tire and wheel assembly mounted on a vehicle, said method comprising: projecting a plurality of light planes from a first light projector onto a tire and wheel assembly to form a plurality of generally parallel illumination lines on a tire of the tire and wheel assembly; receiving a reflected image of at least some of said illumination lines with a photo electric device, said photo electric device receiving images of said illumination lines reflected from the tire at an angle relative to a projecting angle of said first light projector; and determining a plane defined by spatial coordinates from a selected point located on each said illumination line imaged by said photo electric device, said plane representing the orientation of the tire and wheel assembly and wherein said determining step further comprises: resolving three dimensional spatial coordinates for multiple points located on each said illumination line imaged by said photo electric device; deriving a best fit curve equation for each said illumination line using the three dimensional spatial coordinates from said resolving step; and determining said plane as a best fit tangential plane to the curve equations for each said illumination line from said deriving step, wherein the intersection of said plane with the curve equations defines said selected point located on each said illumination line.