Method for correcting angle measurement error of circular grating with double reading heads mounted in non-alignment manner

The invention relates to a method for correcting the angle measurement error of a circular grating with double reading heads mounted in a non-alignment manner. The method comprises the steps of firstly, constructing a measurement structure which is used for correcting the angle measurement error of the circular grating and comprises the circular grating and the two reading heads, the circular grating being mounted on a rotating shaft, and the two reading heads being mounted on the two sides of the circular grating in a non-alignment manner; then rotating the rotating shaft for one circle, and collecting the readings of the two reading heads on the circular grating disc; thirdly, fitting the installation eccentricity parameters of the circular grating according to the data acquired in the previous step and a formula; and finally, substituting the installation eccentricity parameters of the circular grating obtained by fitting into an error correction formula to obtain a corrected angle measurement value. Accor