Guidance Law Design With Angular Constraints

The study of guidance law is closely related to actual needs.The design of traditional guidance law(tracking method,lead angle method,proportional guidance,etc.)only focuses on accurate hits.With the increasingly complex battlefield environment and the replacement of hostile targets,traditional guidance methods are gradually unable to meet actual needs.Considering the practical application of medium and long-range airto-air missiles and the restriction for the relative spatial relationship between the missile and the target to meet special tactical needs,it is necessary to study the guidance law with angular constraints.This paper first discusses the connotation of angular constraints.At the same time,based on the sliding mode control theory,a guidance law with line of sight constraints with damping terms is designed.Based on this,a guidance law with field of view constraints is designed.The condition-constrained angle constraint guidance laws are designed and implemented respectively with field-of-view constraints,time-angle constraints,and acceleration-angle constraints.Finally,for the non-ideal conditions of inaccurate sight angle measurement and target loss,the angular constraint guidance law considering measurement noise and the angular constraint guidance law considering target loss are designed.The main work of this article is as follows:(1)Research on guidance law with angular constraints based on the line of sight constraints.The concept of angular constraint is extended to two types of constraints: the end attack angle constraint and the process Brewster angle constraint.Considering the energy consumed by the missile will change its range,a terminal angle constraint guidance law with a damping term is designed to reduce the missile maneuver in the middle guidance stage based on the above basis,research another type of damping term,design guidance law with the Brewster’s angle constraint,improve guidance accuracy at the final guidance stage;analyze the relationship between the field of view angle and the line of sight angle,based on viewing angle constraint guidance law and switching strategy,design guidance law with only field angle constraint.The simulation test results show that the guidance law designed in this paper not only meets the target and related constraints,but also has smaller energy consumption and faster convergence speed.(2)Study the angular constraint guidance law under multiple constraints.Based on the sliding mode control theory,the field of view constraint is transformed into a constraint on the relative velocity of the projectile and the target in the vertical line of sight.A guidance law that satisfies both the field of view constraint and the attack angle constraint is designed.The guidance law with time-angle constraints,the design does not require a small angle assumption or approximate time estimation of the sliding mode surface function;for the sliding mode guidance law analyzes the factors on the acceleration command size,by designing a new reaching law to achieve the limit on the magnitude of the acceleration,to achieve the accelerationangle constrained guidance law.The simulation test results show that the related guidance law designed in this paper satisfies a variety of constraints including angular constraints while guaranteeing hits.(3)Study the angular constraint guidance law under two types of nonideal conditions.Under non-ideal conditions,considering the key measurement value of the guidance law with angular constraint—the problems caused by inaccurate sight angle measurement and target loss,the sight angle measurement value is regarded as the real value plus the noise term,and is based on no trace Kalman filtering performs one-step prediction to denoise;analyzes the effect of target loss on the guidance law with angular constraints,and abstracts a class of practical problems into scenes of target loss recapture,supplementing target missing values based on combined prediction information.Simulation test results demonstrate that the proposed method can effectively scale down the adverse effects of these two non-ideal conditions on the guidance law.