Study on the method of error separation and compensation based on multiple signal superposition for time grating angular displacement sensor

A method of error separation on the principle of multiple signal superposition is introduced for time grating angular displacement sensors. According to the theory of error compensation, the accuracy of time grating sensors can be improved by compensating the separated errors. Errors of time grating angular displacement sensors caused by stators and rotors during manufacturing are separated and majority long-periodic and short-periodic errors are removed using this method. Thus, error compensation model can be established for these separated errors using the method of harmonic analysis. Circular indexing errors caused by slots of stators and rotors of time grating sensors can be compensated using this model. The accuracy is improved significantly to a field-type time grating by the error compensation model. The precise is 2.8″ after calibrating. Experiments prove that the method of error separation is very effective for removing indexing errors and the established error compensation model shows obvious effect in calibrating errors of time grating angular displacement sensors.