The dithering of mechanically dithered ring laser gyro(DRLG)leads to pseudo coning motion in the strap-down inertial navigation system(SINS).The influence of the pseudo coning motion on calculation of the rotating vector of SINS is analyzed,and the formula is deduced.To minimize the pseudo coning error,the influcence factors are analyzed by numerical calculation,and the matching principle of dithering frequency difference among different DRLGs in SINS is recommended.Based on the principle,a dithering freque...