Patent ID: 8482607

Claim:
An optical apparatus for measuring absolute mechanical displacement of actuators, joints, or other mechanical apparatus that contain mechanical parts that move with respect to each other, comprising: a. an optical means of measuring relative displacement of second part of said mechanical apparatus with respect to first part of said mechanical apparatus where said optical means is fixed to said second part of said mechanical apparatus and where said second part is any of the parts of said mechanical apparatus, such that said optical means of measuring relative displacement is directed at the surface of said first part of said mechanical apparatus where said first part is any of the other parts of said mechanical apparatus such that said optical means of measuring relative displacement is able to detect relative displacement distance of said surface of said first part of said mechanical apparatus, and such that marks created on said surface to stand out from natural optical patterns on said surface are not required by said optical means of measuring relative displacement, b. one or more calibration positions, such that the absolute displacement of said first part of said mechanical apparatus at said calibration positions is known, c. a means of detecting calibration position alignment, such that said first part of said mechanical apparatus and said second part of said mechanical apparatus are aligned at said calibration position, d. an estimated absolute mechanical displacement that is a summation of the cumulative net relative displacement obtained by said optical means of measuring relative displacement since a detected said calibration position alignment and the known absolute displacement at said detected calibration position alignment, such that said estimated absolute mechanical displacement is equal to said known absolute displacement when said first part of said mechanical apparatus and said second part of said mechanical apparatus are aligned at said detected calibration position alignment and such that if one or more correction multipliers are available, one or more said correction multipliers are applied to said cumulative net relative displacement and/or individual relative displacement measurements obtained by said optical means of measuring relative displacement comprised in said cumulative net relative displacement, whereby the measured absolute displacement of said first part of said mechanical apparatus is corrected at said calibration positions and does not require adjacent said calibration positions, whereby the absolute displacement of said first part of said mechanical apparatus is estimated with accuracy and precision by said optical means of measuring relative displacement allowing for a reduction in the number of said calibration positions, whereby the apparatus cost is reduced through the reduction in required number of said calibration positions.