Research On Finite-time Guidance Law And Cooperative Guidance Law Of Multi-missiles For Intercepting Maneuvering Target

As the environment of modern combat is getting more and more complicated and the performance of highly maneuverable targets is getting more and more improved,the missiles have not only high guidance precision but also the capability of cooperative battle with other multiple missiles to improve the intercept probability against highly maneuverable targets.At the terminal guidance,target often escapes with high maneuvers,the information of the target maneuver may not be easily obtained precisely,and the time left to practical terminal guidance must be limited and very short,sometimes only a few seconds.Therefore,high precision guidance laws and multiple missiles cooperative guidance laws existing dynamic information sharing in the process of guidance with strong robustness to target maneuver and finite-time convergent rate are needed to design.Hence,under the background of single missile or multiple missiles intercepting single highly maneuverable target at the terminal guidance,this dissertation works on the problem of the design of finite-time guidance law and finite-time multiple missiles cooperative guidance law.The main contents are as follows.Firstly,considering the target acceleration as bounded external disturbance with unknown bound,finite-time guidance laws with terminal impact angle constraint are investigated.The model of a guidance system with terminal impact angle constraint is established in plane.Based on this model,a finite-time stable guidance law,is designed using the nonsingular fast terminal sliding mode control and adaptive control.In the design procedure,the upper bound of the external disturbance does not need to estimated a priori.Instead,an adaptive law is presented to estimate the unknown upper bound online.On this basis,to better improve guidance performance,a high accuracy finite-time convergent disturbance observer is employed to estimate the external disturbance.And a nonlinear disturbance observer-based finite-time convergent guidance law is put forword.Furthermore,the model of a guidance system with terminal impact angle is established in three-dimensional space.Based on this model,a three-dimensional finite-time convergent guidance law is presented using the integral sliding mode control and adaptive control,where the upper bound of external disturbance is estimated online by a designed adaptive law.Simulation results show the missile under the designed guidance laws can intercept the target with desired terminal impact angle successfully for different target maneuvering profiles and the designed guidance laws have strong disturbance rejection ability and high guidance precision.Secondly,considering the target acceleration as bounded external disturbance with unknown bound,continuous guidance law with terminal impact angle constraint,second-order dynamics of missile autopilot and missile acceleration saturation constraint is investigated.The model of a guidance system with the above mentioned three constraints is established in plane.Based on this model,a continuous guidance law with the above mentioned three constraints is designed using backstepping method,command filtering and adaptive control.The proposed guidance law can guarantee that the line-of-sight(LOS)angular rate and LOS angle are asymptotically convergence.Furthermore,the model of a guidance system with the above mentioned three constraints is established in three-dimensional space.Based on this model,a three-dimensional continuous finite-time stable guidance law with the above mentioned three constraints is developed using backstepping method,additional system,nonsingular fast terminal sliding mode control and adaptive control.In the process of design,an additional system is constructed to deal with the acceleration saturation problem,and its states are used to backstepping design.The proposed three-dimensional guidance law can guarantee that the LOS angular rate and LOS angle are finite-time stable.In the design procedure of both two guidance laws,an adaptive law is presented to estimate the unknown upper bound of the external disturbance online.Simulation results show that the proposed continuous guidance laws are able to compensate for the autopilot lag and the effect of acceleration saturation.They can provide a high guidance precision on intercepting a maneuvering target with desired terminal impact angle successfully.The chattering problem in the existing traditional sliding mode control guidance law can be alleviated effectively.Thirdly,considering the target acceleration as bounded external disturbance with unknown bound,finite-time cooperative guidance law with terminal impact angle constraint is investigated under connected undirected graph.The multiple missiles cooperative guidance model with terminal guidance time-to-go accounting for terminal impact angle constraint is constructed in plane.Based on this model,a finite-time convergent cooperative guidance law is designed using finite-time consensus of multi-agent systems,sliding mode control and adaptive control.Furthermore,the multiple missiles cooperative guidance model with terminal impact angle constraint is constructed in three-dimensional space.Based on this model,a continuous finite-time stable cooperative guidance law in three-dimensional space is designed using finite-time consensus of multi-agent systems,super-twisting algorithm,sliding mode control and adaptive control.Simulation results show that the proposed cooperative guidance laws can guarantee that all missiles intercept the target with desired impact angle simultaneously and the designed guidance laws have strong disturbance rejection ability and high guidance precision.Finally,considering the target acceleration as external disturbance,continuous finite-time convergent cooperative guidance law with leader-follower cooperative strategy is investigated under directed graph.The leader-follower cooperative guidance model with terminal guidance time-to-go is constructed in plane.Based on this model and combined with super-twisting algorithm and adaptive control,continuous finite-time convergent cooperative guidance laws are designed for the derivative of external disturbance with known bound and the second derivative of that with unknown bound,respectively.Theoretical analysis proofs that the both two guidance laws can make the time-to-go of followers converge to the leader's in finite time and all missiles' LOS angular rates converge to zero in finite time.Simulation results show that the proposed cooperative guidance laws can guarantee that all missiles intercept the target with high guidance precision in finite time simultaneously and the designed guidance laws have strong robustness.