Key Technology Of Roll-Pitch Seeker And Its Application To Air-to-Air Missile

The main objective of this dissertation is study on the theoretical problem of roll-pitch seeker and the key technologies when applied to air-to-air missiles.The research can provide theoretical basis for overall design of roll-pitch seeker and its application in air-to-air missiles.The findings can directly serve the industrial sector,and provide important support to the engineering development.Firstly,the technical investigation of foreign new generation air-to-air missile is done by combing the development trend of air-to-air missile.By summarizing the development of advanced seeker technology and its application in air-to-air missile,the main research object is identified as semi-strapdown roll-pitch seeker based on Kurdish light path.Then the current research of this field is reviewed,including the development of roll-pitch seeker technology,the isolation of the LOS angular velocity of the semi-strapdown seeker and the study of Disturbance Rejection Effect(DRE).Secondly,the function and composition of seekers is introduced.The transformation relations of different coordinate systems are deduced based on the definition of the coordinate systems of roll-pitch seeker.The error angle transfer characteristic between the strapdown detector and the virtual inner frame detector is deduced by analyzing the Kurdish light path of roll-pitch seeker.The infrared imaging seeker is taken as an example to simulate the system.The results show that the angle motion of the projectile will lead to the rotation of the target image on the detector.Thirdly,by comparing light spot motion law on the Imaging sphere of roll-pitch seeker and pitch-yaw seeker,the tracking principle of roll-pitch seeker is analyzed.According to the motion law of the frame of the roll down seeker,two methods for calculating the command in form of frame angle increment are derived based on the coordinate transformation method and the screw theory.The calculation precision of these two methods are tested through mathematical simulation.The singularity problem when the roll-pitch seeker tracking target of small off-axis angle is elucidated from standpoint of target tracking,LOS stabilization and command calculation.To overcome the problem,an overhead control strategy is proposed.Fourthly,the dynamic characteristics of roll-pitch seeker is analyzed.According to the motion relationship of the two frames of roll-pitch seeker,the moment of inertia of the outer frame overload to the missile axis is time-variant.The dynamic equation of the seeker indicates that there are coupling between the two channels,and a decoupling method based on the control torque compensation is proposed.In view of the problem that the semistrapdown seeker can not directly output the LOS angular velocity of the optical axis,three kinds of angular velocity extraction methods are proposed.The nonlinear filtering theory in the Bayesian framework is summarized,and the Extended Kalman Filter(EKF)and the Unscented Kalman Filter(UKF)are used to estimate the frame angular rate of the roll-pitch semi-strapdown seeker.Fifthly,the single channel DRE model of roll-pitch seeker is defined in roll channel and pitch channel respectively.The roll-pitch seeker’s Isolation effect to missile disturbance is analyzed,and a method of detector error compensation is proposed to make the seeker’s control system avoid responding the error due to axial forced motion.The roll channel is taken as an example to analyse the DRE characteristic of single channel of semi-strapdown seeker,the transfer function of DRE caused by back EMF,disturbance torque and scale error respectively is derived.The amplitude and phase characteristics are calculated under typical seeker parameters.The angular velocity of the optical axis is transformed into the inertial system,the coupling model of the pitch and yaw channel in the inertial system is obtained,and the coupling characteristics of the two channels are analyzed.The two channel guidance control model including the DRE parasitic circuit is established,and the influence of DRE parasitic circuit on guidance accuracy is analyzed.Sixthly,to meet the requirements of large maneuvering at the end of the missile,the direct force control has been introduced to air-to-air/surface-to-air missile at the end of its trajectory.It required the missile spin at a certain angular velocity to make full use of the resources of the pulse engine.In this paper,the phased array active radar seeker and passive strapdown interferometer are combined as a composite guidance method.The coupling model of the two guidance loop was established under missile rotation condition,and the reason of the coupling was analyzed.The design requirement of phased array seeker that meet the decoupling condition is presented.The angle measurement principle of passive strapdown interferometer is studied under missile rotation condition,and then the decoupling methods based on dynamic gyro and angular velocity gyro are analyzed in detail.At last the composite guidance information fusion tracking mode of active phased array + passive interferometer seeker is studied.