Calibration Method of Autocollimator Focal Length and Mounting Axis in Optoelectronic-Inertial Boresighting System

Aircraft boresighting equipment is used to measure and calibrate the angles between the axes of fighter aircraft's onboard weapons and related equipment, which is one of the keys to ensuring the striking accuracy of the weapon system. As a new type of boresighting equipment, the optoelectronic with strapdown inertial navigation system(SINS) boresighting equipment(hereinafter referred to as the optoelectronic-inertial boresighting equipment) adopts the cooperative measurement method of autocollimator and SINS to measure and calibrate the relevant axes. Among them, the focal length of the autocollimator (hereinafter referred to as the focal length) and the mounting error of the axis between the autocollimator and the SINS(hereinafter referred to as the mounting angle) are the main factors affecting the measurement accuracy of boresighting equipment. In order to improve the measurement accuracy of the optoelectronic-inertial boresight equipment, this paper proposes a calibration algorithm for the focal length and mounting angle. The accurate focal length and mounting angle values are obtained by deriving the measurement model and data fitting. The static measurement experiment results show that the measurement error RMS are $\sigma_{{_{-}yaw }}=0.0005^{\circ}(1 \sigma)$ and $\sigma_{\_}\text{pitch} =0.0007^{\circ}(1 \sigma)$ after calibration. The method can significantly improve the measurement accuracy of the optoelectronic-inertial boresightting equipment, which is suitable for high-precision calibration.