Patent ID: 7434740
Filing Date: 2008-10-14
Classification: G01D,G01P

Abstract:
1. A method of detecting the position of a sequence of markings on an object in relation to a detector, said sequence of markings having a plurality of portions and said method comprising: a) detecting, using the detector, the plurality of portions of the sequence of markings on the object; b) generating, using the detector, an output based upon the plurality of portions of the sequence of markings; c) supplying a reference sequence previously stored in a storage medium separate from the markings on the object and corresponding to the sequence of markings on the object; d) comparing a plurality of portions of the generated output with a plurality of portions of the reference sequence; e) generating an error signal if the comparison does not result in a complete correspondence between the plurality of portions of the generated output and the plurality of portions of the reference sequence; and f) modifying, responsive to the generation of the error signal, at least one step of a group consisting of step a, step b, step c and step d, to increase a correspondence between a subsequent generated output and the sequence of markings, said modification based at least in part on a number or recurring generations of error signals for a plurality of comparisons.