Mutual Calibration Method of Ring Laser Gyro and Optical Shaft Encoder

The calibration of a rotary table enables the quantitative evaluation of its performance and the traceability of angular motion parameters. However, there are few studies on the calibration method or equipment of rotary tables, especially for dynamic rotary tables. Existing measurement methods do not meet the requirements for rotary table calibration in terms of measuring range, accuracy, feasibility, and simplicity of assembly. This article presents a mutual calibration method based on a ring laser gyro and an optical shaft encoder. The scale factor of the ring laser gyro measurement model was calibrated based on the optical shaft encoder zero-position signal and the principle of full-circle closure. The ring laser gyro itself has the characteristics of high resolution and ideal circle segmentation. Therefore, the calibrated one is used to identify the parameters in the harmonic model established by the measurement error of the optical shaft encoder, and the measurement accuracy of the optical shaft encoder is improved by compensating for the error. Experimental results show that the mean measurement error of the ring laser gyro based on optical shaft encoder zero-position signal calibration is reduced by 72.38%, and the mean measurement error of the optical shaft encoder based on ring laser gyro measurement results compensation is reduced by 9.13%. The optical shaft encoder and the ring laser gyro are used to measure dynamic motion separately after mutual calibration, which makes the measuring system easy to install, debug, and operate, and has the advantages of wide range and high precision.