Abstract: A stabilizing and tracking control strategy of using a strapdown inertial navigation system(SINS) to measure the pointing direction and angular rate of gun barrel is proposed to enable the mar-ching guns to track targets and stabilize at a large fire angle, in which the stabilizing and tracking control are accomplished in the geodetic coordinate system. The conventional three-loop control is applied and improved, and the reference and feedback values of position loop and velocity stabilization loop are given in the geodetic coordinate system. As the position feedback, the azimuth and pitch angular rates of SINS are resolved based on the geodetic coordinate system. The measured values of gyros in SINS mounted on the gun are transformed to the azimuth and pitch angular rates in the geodetic coordinate system, and re multiplied by the drive ratios of drive mechanisms as the feedback of velocity stabilization loop. A dynamic coupling model of gun, turret and carrier is established using Lagrange equation in consideration that the rotary center of turret and carrier is misaligned, and the carrier moves in six degrees of freedom. The simulation validation of the proposed control scheme is conducted based on SINS measurement model, two-motor drive model and control model of motor servo system. The result shows that the two-channel independent control, the high-accurate stabilizing control of pointing direction of gun at a large fire angle, the high tracking performance in a certain range of firing angle, and the isolation of wider frequency band disturbance from carrier can be realized. Key

Key words: gunpointing, stabilizingandtracking, strapdowninertialnavigationsystem, Lagrangemethod, dynamiccoupling, doublemotordrive