Abstract: To solve the problem of that the traditional inertial navigation system can’t be used in the high speed rolling guided projectile, a partial strapdown platform with special structure is introduced. This platform can keep the micro inertial measurement unit (MIMU) stabilize on the roll axis and remain strapdown on the pitch and yaw axes. The principle of compound pendulum is considered in the design of platform. The stability of the platform is related to the restoring torque of the mass eccentricity. A mechanical dynamics model is established by mechanical analysis of projectile and partial strapdown platform. The roll angle and angular velocity of the platform’s inner shell at different pitching angles are obtained by applying the Runge-Kutta method to solve the differential equations of motion. The experiment is done in three-axis flight simulation test platform. The mechanical dynamics model is verified. The results show that the smaller the missile flight pitching is, the smaller the angle and the angular rate of the partial strapdown platform’s inner shell rolling are, and the more stable the partial strapdown platform is.

Key words: ordnance science and technology, inertial measurement system, guided projectile, partial strapdown platform