Method and System for Estimating Positions Using Absolute Encoders

摘要

A position is determined by sensing a signal corresponding to a subsequence of marks in a non-periodic sequence of the marks on a scale. A coarse position PA is determined by matching the subsequence with all possible subsequences of the non-periodic sequence. Threshold-crossings corresponding to rising edges of the signal and threshold-crossings corresponding to falling edges of the signal are detected. An position correction Pi is determined using the threshold-crossings. The coarse and the position correction are summed to obtain the position.

主权项

1. A method for determining a position on a scale, comprising steps of:
sensing a signal S corresponding to a subsequence of marks on the scale, wherein the scale includes a sequence of the marks; determining a coarse position PA by matching the subsequence with all possible subsequences of the sequence of marks; detecting threshold-crossings corresponding to rising edges of the signal S and threshold-crossings corresponding to falling edges of the signal S; computing a position correction Pi using the threshold-crossings; and summing the coarse position PA and position correction Pi to obtain the position on the scale, wherein the steps are performed in a digital signal processor.