Patent ID: 7420477
Filing Date: 2008-09-02
Classification: G01D

Abstract:
1. A method for computing an enhanced absolute position reading for a sensed axis comprising: (a) providing a first absolute encoder that is coupled to the sensed axis so as to rotate in concert with the sensed axis; (b) providing a second absolute encoder which is coupled to the sensed axis so as to rotate an integer number of times greater than one for each single rotation of the sensed axis; (c) providing a means by which data may be read from the first absolute encoder and the second absolute encoder; (d) providing a non-volatile memory that is able to store a plurality of data; (e) providing a general purpose computer for the purpose of the reading and manipulation of data from the first and second absolute encoders, storage of data in the non-volatile memory, selecting from a plurality of formulas for the purpose of computing the enhanced absolute position reading and for the transmission of the enhanced absolute position reading which will; whereby the enhanced absolute position reading of the axis as reported by the first and second encoders and processed by the general purpose computer will not be degraded by mechanical misalignment between the first and second encoders or by reasonable temporal misalignment between the readings of the first and second encoders and which will not require repeated initialization of the fine and course offsets even in the event of power loss.