Patent ID: 7805270

Claim:
A method for identifying the position of a first member relative to a defined path; said path being defined by a second member; one of said first and second member providing a periodic field along at least a portion of said defined path, said method comprising: (a) providing a plurality of predetermined sets of N sequentially ordered values, where N is greater than 2, each set associated with a pre-identified position of said first member relative to said defined path; (b) providing an array of spaced field sensors positioned at fixed locations with respect to the one of said first and second member not providing said periodic field and adjacent to at least a portion of said defined path, each of said field sensors sensing said portion of said periodic field at its fixed location and thereby generating a sensor signal in response thereto to provide a set of N sensor signals in a predetermined sequence associated with the position of said first member relative to said defined path; (c) comparing said set of N sensor signals to a first one of said plurality of predetermined sets of N sequentially ordered values associated with a first pre-identified position to generate a correction signal; and (d) using said correction signal to choose another pre-identified position associated with another one of said plurality of predetermined sets as an approximation of the position of said first member relative to said defined path; and (e) generating a position output signal associated with said approximation of the position from step (d).