Multi-target Distribution And Study On The Terminal Guidance Law With Constraint For Exo-atomospheric Spacecraft

When atmospheric intercept missile is used to intercept ballistic attack missile,the relative speed is extremely fast which needs interceptor to make a quick response,and eventually to kinetic energy collision kill the target.This has a very high demand for the guidance of the interceptor.Taking into account the target will have a maneuver situation,which requires the terminal guidance law has not only high precision,but also a strong robustness.In view of the above problems,this paper has carried on the thorough research in the following several aspects:When the multiple interceptors in the atmosphere face multiple incoming targets,this paper considers the degree of target threat.Through the genetic algorithm and other related principles,the distribution strategy is optimized to find the optimal solution,which converts many-to-many problems into multiple single-to-single precision final guidance problems.Then,a three-dimensional smooth super-twisting guidance law is proposed based on sliding mode control.This method is different from the traditional sliding mode,it can generate a smooth guidance signal,effectively suppress the generation of chattering.In addition,the guidance law can ensure that the rotational speed of the line of sight converges to zero in finite time with the second order sliding mode precision,which guarantees the demand of kinetic energy.Since the smooth super-twisting algorithm has invariance to the matched Lipschitz perturbation,the guidance law is highly robust and can effectively deal with the target maneuver.In order to further enhance the robustness and weaken the chattering,we introduce an exact robust differentiator to estimate the target maneuvering acceleration in finite time,and then feed forward compensation in the guidance law.For the sake of increasing the degree of damage to the target missile,intersection angle constraints is usually added in terminal guidance mission.This paper deduces the geometric relationship between the expected trajectory inclination and the desired line of sight in the case of three-dimensional guidance.Generalized super-twisting algorithm as an improved algorithm for super-twisting algorithm,can achieve faster response speed.Based on the expected line of sight,we use the generalized super twisting reaching law to construct the three-dimensional terminal guidance rule with angle constraint.In order to improve the killing effect of the interceptor by achieving multiple interceptors at the same time to intercept a target,we made request for the impact time.In this paper,the attack time constraint problem is transformed into the relative distance tracking problem,and the expected trajectory inclination is modulated.Then generalized super-twisting guidance law is used to achieve the trajectory inclination angle converge to the expected value within a finite time,so as to ensure that the interceptor hit the target at the scheduled time.