Research On Online Compensation Methods For Radome Error Of Seeker And Beam Direction Error Of Phased Array Seeker

In order to fulfill the overall technical requirements of radar seekers, this dissertation mainly studies the effects of seeker radome error and seeker disturbance rejection rate(DRR) on missile guidance performance, and online compensation methods for the radome error and DRR.Firstly, the generation of radome error is analyzed, and the model of radome parasitic loop is established. The stability and time/frequency domain performance of radome parasitic loop, the effects of radome parasitic loop to guidance performance are studied respectively. Furthermore, the miss distance influenced by radome error is analyzed with inputs of six error sources, inlcuding initial velocity direction error, constant target maneuvering, glint noise, receiver noise, fading noise and random target maneuvering. Theoretical analysis reveals that the radome parasitic loop not only shrinks the stable region of the closed-loop guidance system, but also increases the miss distance, and this situation is getting more worse when radome error slope changes randomly during interception.In order to comparatively analyze the effect of radome error on proportional navigation guidance(PNG) law, velocity pursuit guidance(VPG) law and trajectory shaping guidance(TSG) law, comparable guidance systems of PNG and VPG, comparable guidance systems of PNG and TSG are established. The influence of radome error on missile guidance performance in different guidance systems are studied comparatively. Theoretical analysis reveals that the stable region of VPG parasitic loop and guidance loop is larger than PNG, and VPG miss distance caused by radome error with inputs of velocity direction error and glint noise is smaller than PNG, but with input of random target maneuvering, VPG miss distance is larger. The stable conditions of TSG parasitic loop and guidance loop are equivalent to PNG, but TSG miss distance caused by radome error is larger than PNG.At present, process control, adding guidance filter, negative feedback offset and ground calibration methods commonly used in engineering have limited effect in radome error compensation. In order to reduce the bad influence of radome error on guidance system, this dissertation proposes several radome error online compensation methods, mainly based on multiple model, EKF and pole placement self-tuning control. The compensation effects under different conditions are also analyzed. Theoretical analysis reveals that the influence of radome error on guidance system can be reduced effectively and the guidance accuracy can be improved significantly by using the proposed online compensation methods.The generation of strapdown phased array radar seeker DRR is analyzed based on seeker working principles, and the DRR models considering radome error are established. The influence of different DRR models on guidance system performance is comparatively analyzed, and the online compensation methods based on multiple model and EKF for strapdown phased array radar seeker DRR are proposed. The research results show that beam direction error and radome error slope are the main DRR factors which have a strong impact on missile guidance system stability and guidance accuracy. Furthermore the influence of positive feedback of parasitic loop is more serious. The DRR caused by beam direction error and radome error slope can be compensated as a whole by the proposed online compensation method, which can greatly improve the overall guidance performance.Finally, DRR models of platform radar seeker considering radome error are established, and the influence of different DRR models on guidance system stability and guidance accuracy is comparatively analyzed. To compensate for the effect of DRR an online compensation method using UKF is proposed, and the comparison between UKF and EKF is presented. Theoretical analysis reveals that spring torque, damping torque and radome error slope are the main factors which induce the platform radar seeker DRR. Performance analysis shows that positive radome error slope has small influence on guidance performance, while the influence of spring torque and damping torque is relatively larger. Additionally the influence of negative radome error slope is the most serious one. With the help of proposed UKF based online compensation method, the DRR of platform radar seeker can be inhibited effectively and the performance of guidance system is improved. Compared to EKF, the UKF algorithm has higher estimation accuracy and better online compensation effect.