Design And Implementation Of ADRC-Based Tracking Radar Antenna Servo Systems

Tracking radar antenna servo system is widely used in the areas of targets searching, air defense, communication, object location, etc. The control circuit is one of the most important portions to determine the performance of the servo system. Controller,the central component of the control circuit, influences the efficiency and accuracy of the control algorithm during the execution process. Therefore, it has a key impact on the whole performance of the system. Many factors such as the parallelism of the azimuthal and elevation loop, the rapidity and accuracy of the servo system, the low power consumption and circuit’s size are taken into consideration. A full digital circuit based on FPGA and LMD18200 is designed.Resolvers are chosen as the position transducers in tracking radar antenna servo system, due to their low cost and high reliability. The realization of resolver to digital conversion is the foundation of high performance tracking radar antenna servo system.In this thesis, we introduce the traditional conversion schemes first. A novel conversion strategy is then designed. The proposed method takes advantage of the auxiliary sinusoidal signals generated by addition and subtraction operations of the demodulated signals of resolver’s outputs. Its superiority is further validated by the comparison on the experiment results.Tracking radar antenna servo system is a complex system with the property of nonlinear and strong coupling. A modified active disturbance rejection controller(ADRC)for radar servo system is also presented. This strategy focuses on dealing with the coupling problem between the azimuthal and the elevation loop. What’s more, both the external and un-model disturbance are suppressed by using the ADRC-based controller.The nonlinear mathematical model to describe the dynamic process of the system is given. The procedure of dealing with the nonlinearity, coupling and saturation issues are also provided.The design methodology and novel strategy presented in this paper are tested on the tracking radar antenna servo system. The experimental results obtained under different test conditions with different design approaches further validate the effectiveness of the proposed methods. The advantage of FPGA in dealing with the parallel process,the benefit of using ADRC to handle the uncertain disturbance are also verified.