Abstract: A strapdown inertial navigation system (SINS) is used to measure the pointing of gun barrel for aiming for a tracked self-propelled gun. However, it causes the control coupling of pitching servo and azimuth servo, and the aiming accuracy can be easily affected by vehicle posture. According to the full closed-loop aiming system model under vehicle coordinates, the servo control model under quasi geodetic coordinates including the disturbance of mismatched uncertainty is obtained. Active disturbance rejection controllers (ADRCs) are designed for each axial servo system, considering the coupling and modeling errors to be external disturbance. ADRC can observe the external disturbance and compensate the nonlinear state error feedback controller to eliminate the overshoot caused by it. Thef servo aiming system is simulated under the conditions of initial attitude of vehicle level and inclination of 6 degree. The results show that, compared with the adaptive sliding mode variable structure control, the servo system using ADRC strategy obtains more steady and more accurate targeting results, and gets smoother controller output, meanwhile suppresses the unmatched uncertain interface effectively.

Key words: ordnance science and technology, self-propelled gun, SINS, servo system, unmatched uncertainty, active disturbance rejection controller