Study On Guidance Law And Cooperative Guidance For Multi-missiles Based On Finite-time And Sliding Mode Theory

With the rapid development of missilery and the gradual increase of space strategic position of missile, to better master the initiative of the battlefield, study on the advanced guidance law of homing missile becomes a task with important strategic significance and profound application prospect. This thesis takes the tactical missile of compound control intercepting the maneuvering ballistic missile as the backgound, and it involves two major aspects of research content:(a) the design of guidance law with attack angle constraint, dynamic delay, and external disturbance,(b) the formation flight control and cooperative guidance of multi-missiles.In order to make the warhead of a missile give play to a maximum efficacy and obtain a best damage effect, during the design of guidance law, missdistance has not been the only technical indicator which should be considered. In many complicate battlefield environments, the angle of the terminal guidance also needs to be constrained. In this thesis, for the guidance of a missile intercepting a maneuvering target in the two-dimensional plane, it converts the expected terminal attack angle constraint into the expected line-of-sight angle constraint, and designs a sliding mode guidance law. At first, an asymptotic and a finite-time convergent sliding mode surfaces are respectively selected. By assuming that the autopilot is ideal, and using a finite-time convergent non-homogeneous disturbance observer to track and estimate the target disturbance, two types of sliding mode guidance laws with attack angle constraints are designed. Then, through combining the nonsingular terminal sliding mode surface with the fast power reaching law, an adaptive nonlinear sliding mode guidance law with attack angle constraint is proposed. Finally, the effectiveness and feasibility of designed guidance laws are proved by simulations.In the guidance system of missile, the dynamic delay of the autopilot is one of the major factors that impact the guidance accuracy. To avoid the decrease of guidance accuracy caused by dynamic delay, the dynamic delay is approximated to be a first order inertial element, and a model of guidance system with dynamic delay is directly built. Firstly, based on this model, finite-time convergent guidance laws are designed on the basis of the finite-time control theory, which applies an extended state observer and a non-homogeneous disturbance observer to estimate the target acceleration in the guidance system, respectively, and employs the state feedback to compensate the total disturbance of the system. Secondly, two sliding mode guidance laws are presented by selecting the linear sliding mode surface with expected line-of-sight angle and line-of-sight angular rate, combining with the fast exponential reaching law and the sliding mode variable dynamic approach, and applying the a non-homogeneous disturbance observer to estimate the total disturbance in the system in finite time. Thirdly, an adaptive nonlinear sliding mode guidance law is proposed by selecting a nonsingular terminal sliding mode surface. Finally, the designed guidance law with excellent guidance performance is verified by simulation.Since the fractional order sliding mode has the advantages of both fractional order calculus and sliding mode theory, it is applied in the design of guidance law. By selecting a fractional order linear sliding mode surface and a fractional order terminal sliding mode surface, and comprehensively taking into account the attack angle constraint, the first-order dynamic delay of autopilot and the external disturbance, an asymptotically stable and a finite-time convergent fractional order sliding mode guidance laws are presented, respectively. Results of comparison simulations with traditional sliding mode guidance law show that the designed one has good robustness.Using multiple missiles to attack the target from different directions could improve the ability of defense penetration and target destruction. In the cooperative attack process of missiles, in order to effectively utilize the terrain information to form sheltered attack or avoidance, it is necessary to design a control law of formation according to the terrain and target information in real time.For the formation flight system of missile, by considering the influence of external disturbance like airflow and strong wind in the process of missile flight, a robust adaptive cooperative control strategy of missile formation is proposed, and an algorithm of controling the team formation of missile is also designed. Considering the communication time delay among the missiles, the conditions for asymptotic stability of the system is presented by Lyapunov analysis. Based on the previous research on guidance laws with attack angle constraint, according to the fact that the distance between the missile and target gradually approches to zero in the guidance process, an expected distance curve between missile and target is designed. Moreover, based on the principle of adjusting the attack time first and then adjusting the attack angle, a cooperative guidance law is also designed.