With the development of unmanned military technology， unmanned short-range air combat has attracted much attention from military powers in the world. Faced with the threat of high-speed and high-maneuverability attacker missiles， traditional passive defense measures such as throwing chaffs or releasing hot flame bombs fail to ensure the safe escape of target aircraft. It is a feasible method to implement active defense by launching defender missiles to coordinate the maneuvering of target aircraft. However， due to the strong maneuverability of the attacker missile and unknown acceleration information， it is difficult to design the guidance law of cooperative target aircraft-missile. An active defense line-of-sight （LOS） guidance law based on disturbance compensation was proposed in this paper. A nonlinear disturbance observer was designed to estimate the influence of the maneuverability from the attacker missile， which was compensated for in the design of active defense LOS guidance law for the cooperation of aircraft and missile. The results of the simulation indicate that the method used in this paper can effectively defend the attacker missile with unknown maneuverability. The study in this paper thus provides a reference for the three-body attack and defense problem.

A control strategy based on disturbance compensation is devised to address the issue of stabilizing trajectory tracking for quadcopter unmanned aerial vehicles （UAVs） with unknown external disturbances. Firstly， this paper designs a PID position controller for the quadcopter UAV’s position loop and compensates for external disturbances using a disturbance observer. Secondly， the desired attitude is obtained through attitude computation， and an incremental nonlinear dynamic inversion（INDI） attitude controller with strong robust performance is designed for the quadcopter UAV’s attitude loop. Finally， simulation and comparative experiments are conducted by Simulink. Experimental results indicate that this control strategy can achieve trajectory tracking capability for quadcopter UAVs under conditions of unknown external disturbances.

Due to the mismatch between the tracking model and the real motion state of the target， the estimation accuracy of the high order motion feature of the target is poor in single-station radar.In this paper， the estimation accuracy of high order motion feature of the target is improved from the perspective of radar networking and radial velocity augmentation measurement. The sequential unscented Kalman filter algorithm is used to centrally fuse the asynchronous measurement information of multiple radars. The estimation effect of the high order motion feature of the target under different ranging， angular accuracy and radial velocity augmentation measurement is analyzed， and the influence of the radar station layout on the estimation effect of the high order motion feature of the target is analyzed by using the geometric accuracy factor of double sensors to optimize the radar station layout. Through simulation experiment， it is found that the radar ranging accuracy in this radar networking mode has a greater impact on the estimation effect of high order motion feature than the angle measurement accuracy. Radar station layout optimization combined with radial velocity augmentation measurement can effectively obtain high precision estimation of high order motion feature of target.

In order to achieve the intercept mission requirements， an improved optimal guidance law is derived considering the angle constraint of the interceptor and the premature loss of energy that cannot satisfy the subsequent interception requirements. Based on the structure of energy minimum objective function， a control weighted function is proposed to minimize the required overload in the initial phase and the terminal line of sight （LOS） angle can converge to the excepted value. An angle constraint optimal guidance law is derived in view of small angle assumption and optimal control theory. Based on the characteristics that the guidance law can make the terminal LOS angle converge， the problem of terminal LOS angle is converted into the problem of terminal encounter angle， and the optimal guidance law with terminal-intersection angle constraint is obtained. The simulation results show that the designed guidance law can not only realize terminal encounter angle control， and also ensure low energy consumption in the initial stage of guidance， as well as achieve high hit accuracy. The designed approach has certain reference and application values for the study on the optimal guidance law of interception missile.

Aiming at the shortcoming that the weight coefficient determined by a single expert is too subjective when the AHP method is used to determine the index weight in the current air attack target threat assessment， an air attack target threat assessment method based on cluster combination weighting is proposed. The group AHP method based on cluster analysis is used to determine the expert weight from the two aspects of expert experience ability and the degree of knowledge of a given problem， and then obtains the subjective weight of the indicator； by combining with the objective weight obtained by the coefficient of variation method， the final weight is obtained， and then a fuzzy comprehensive assessment model introducing the Einstain operator is constructed to calculate the threat degree value of the target. The effectiveness and rationality of the method are proved by simulation experiments and comparative analysis.