Methods for reducing failure of spaceborne quasi-absolute optical encoder caused by oil contamination

Abstract

Oil contamination has a detrimental influence on the spaceborne quasi-absolute optical encoder because it introduces errors in angular displacement measurement. To reduce these errors and prevent the failure of the spaceborne quasi-absolute optical encoder caused by oil contamination, this paper proposes a multi-reference identification algorithm for the absolute angular displacement and a multi-reading-head data fusion algorithm. First, the composition of the spaceborne quasi-absolute optical encoder and the design of the processing circuit are introduced. Second, a multi-reference identification algorithm of the absolute angular displacement is proposed to prevent the misidentification of absolute angular displacement due to oil contamination. Moreover, a multi-reading-head data fusion method was employed to determine and eliminate the erroneous reading head measurement data. The effectiveness of this method was verified by experimentally comparing the angular displacement curves and angular velocity curves obtained from a quasi-absolute angular displacement measuring device, with and without the application of the proposed method. The effects of oil contamination on the accuracy of measurement were also compared. The results indicated that after application of the method, the error in the angular displacement measured by the code disk due to oil contamination was significantly reduced, ensuring the correctness and reliability of the angle-displacement measurement, although the accuracy of measurement was still slightly influenced. Thus, the proposed method is considered to have practical value for making the spaceborne quasi-absolute optical encoder better against the influence of oil contamination.