The Controller Of Stabilized Platform For Shipborne Laser Weapons

The shipborne laser weapon system is different from the normal optical tracking system, which requires not only to track the moving targets in the field of view steadily and quickly, but also to lock the beam on a certain point of the target for a certain period of time, which requires the tracking accuracy of angular second. The shipbore laser weapon system will swing with the ship. In this case, the single platform structure is difficlt to achieve such precision because of the friction torque, mechanical resonance and large inertia etc..For the features of high tracking accuracy and the ship swing disturbane of the shipbore laser weapons, the double platform structure of primary and precise was suggested. Primary platform is three-axis strapdown gimbal structure. The controller will transform the ship attitude angles, which provided by ship inertial navigation system, into a equivalent movement of three axes of the primary platform. Then the stabilized control system rotates the primary platform in the opposite direction to achieve a relatively stabilization in inertial space.The precise platform is installed on the primary platform, and primary platform provide a relatively stable base for precise platform. For shipborne laser weapon system, if tracking the moving targets in angle-second precision fast and stably is wanted, the stablilization of line-of-sight(LOS) optical tracker must be ensured. At the same time, the tracking frame is difficult to tracking the target with sensitive reaction-speed, because it bears all the equipment of tracking and scanning. Therefore, the the structure of precise platform is designed as compound macro-micro control. The macro-control system is used to achieve a fast tracking, while isolating the remaining swing error of primary platform and stabilizing the LOS optical tracker. The micro-control is a fast steering mirror system, which is used to ensure high-precision tracking.According to the structural features of the primary platform, a state space model is established. From the state space model it can be found that the model is strictly feedback and state could be detected. The main factor that affects the stabilization accuracy of the primary platform is the nonlinear friction torque, and the sliding mode control can solve the robust control problems under the matching condition. But the friction torque disturbance is mismatched, which can not be compensated by designing sliding mode controller directly. At the same time, the motor as a driver of the primary platform, its parameters are not static. To overcome this disadvantage, an adaptive sliding mode control with PID sliding surface is proposed, and the stability analysis of the closed-loop system is given.The model of macro control system is estibilished, and the model is formed by the LOS stabilization loop and the optical tracking loop. Because there is 20ms target-missing delay in the optical tracking loop, the delay limits system performance, such as reducing the phase margin of the system, increasing the overshoot of system, or making the system oscillation, even instability. Based on Kalman predictor, a tracking control is proposed for the high precision and the target-missing delay problems of macro control system. Tracking control can be divided into two parts:Kalman predictor design and LOS stability control system design. The Kalman predictor is proposed to solve the problem of the target-missing delay and improve the prediction accuracy of the system. A NN-based Backstepping control is designed to solve the mismatched friction torque disturbane problem of LOS stablilization system to improve the tracking accuracy.Finally, a mathematical model of micro-control system is estibilished. For the mismatched hysteresis problem of the driver PZT, a dynamic surface control method is applied to the micro-control system and the stability analysis is given. The simulations of shipborne laser weapons stablilized platform control system show that the primary and precise combination technology and the compound macro-micro control of precise platform isolate the ship swing effectively and the angular-second tracking accuracy has been achieved.