Patent ID: 7423737

Claim:
A method for determining relative velocity between a surface and a velocity detection system, the method comprising: at a first time, capturing a set of outputs from a first photosensor array of the velocity detection system, wherein the first photosensor array comprises an array of pixels, with each pixel generating a pixel-specific output in response to light reflected from the surface, the pixel-specific outputs being representative of the intensity of the reflected light; at a second time that is later than the first time, capturing a set of outputs from a second photosensor array of the velocity detection system, wherein the second photosensor array comprises an array of pixels, with each pixel generating a pixel-specific output in response to light reflected from the surface, the pixel-specific outputs being representative of the intensity of the reflected light, wherein the first and second photosensor arrays are separated by a known separation distance; determining the difference between the set of outputs from the first photosensor array and the set of outputs from the second photosensor array; comparing the difference between the set of outputs from the first photosensor array and the set of outputs from the second photosensor array to a pre-established difference threshold; identifying the elapsed time between the capture of the set of outputs from the first photosensor array and the capture of the set of outputs from the second photosensor array when the comparison of the difference between the sets indicates that the difference is within the pre-established difference threshold; and calculating the relative velocity between the surface and the velocity detection system using the elapsed time and the known separation distance.