Patent ID: 9574915
Date: 2017-02-21
CPC Classifications: G01B,G01D

Claim:
1. A precision calibration method for being applied in a high-precise rotary encoder system, comprising: (1) providing the high-precise rotary encoder system comprising a rotary encoding body having an optical position surface, a laser speckle image capturing module having a 2D image sensor, and a controlling and processing module; wherein the rotary encoding body is connected to a center rotary shaft of a work equipment, and a precision calibration angle being included between the horizontal axis of the 2D image sensor and the horizontal axis of the rotary encoding body; (2) making the rotary encoding body continuously rotate by a constant small angle until the rotary encoding body rotates a full circle, and using the laser speckle image capturing module to treat a laser speckle image capturing process to the optical position surface during the rotation of the rotary encoding body, so as to obtain N frames of laser speckle image from the optical position surface and then store the N frames of laser speckle image in a data base of the controlling and processing module; (3) using at least one image comparison library comprised by the controlling and processing module to treat a first frame of laser speckle image and a N-th frame of laser speckle image in the N frames of laser speckle image with a key features matching process, so as to calculate an eccentric displacement; (4) if the eccentric displacement is less than a position precision of the laser speckle image capturing module, then (5) using the at least one image comparison library to treat each of two adjacent frames of laser speckle image in the N frames of laser speckle image with the key features matching process for obtaining a plurality of displacement vectors, and then N number of angle coordinates corresponding to the N frames of laser speckle image being respectively calculated based on the plurality of displacement vectors; otherwise (6) calculating an average rotation radius of the rotary encoding body, and then calculating N number of coordinate vectors corresponding to the N frames of laser speckle image; and (7) treating each of two adjacent coordinate vectors in the N number of coordinate vectors with an inner product calculation, so as to obtain N number of after-compensation angle coordinates.