Abstract: In order to solve the problem of that the swing angular velocity of the stabilized semi-strapdown platform is increased due to the coning motion of projectile, the variation law of friction torque of bearing driven by the semi-strapdown stabilized platform is analyzed. Based on the novel calculation model of SKF, the friction torque of bearing under the coning motion of projectile is simulated by the Runge-Kutta method. The theoretical value of swing angular rate of semi-stapdown stabilized platform under conical motion is obtained based on the working principle of the stabilized platform. The ground semi-physical test is conducted to verify the theoretically analyzed results. The experimental results are compared with the theoretically simulated results. It shows that there both exist high and low frequency angular rates whose frequency and amplitude are consistent, and the angular rate of low frequency is constant. The frequency of high frequency angular rate coincides with that of projectile roll angular rate. It indicates that the increase in the swing angular velocity of semi-strapdown stabilized platform is due to the changes of its pitch angle and the pressure on bearing resulting from the coning motion of projectile, which causes the friction torque of bearing to change with the roll angular rate of projectile at same frequency, and finally superimposes the angular rate of high frequency on the stabilized platform.Key

Key words: projectile, stabilizedplatform, conicalmovement, SKFbearing, Runge-Kuttamethod