Research On Midcourse Guidance Law Design With Multiple Constraints For Near Space Target Interception

In order to intercept near space target efficiently,this article presents a variety of constraints of missiles’ status when the missiles is switch from midcourse guidance to terminal guidance,including the angle between the line of sight and the body of missiles,missile’s altitude and velocity.Its main contents are as follows:First, in order to accurately describe the relative position and relative motion of the missile and the target, we need to establish corresponding coordinate system and the transformation matrix between this coordinate systems. Then, we set up equations of dynamic and kinematics for missile and target. Finally, we set up their mathematical model.Secondly, we design the appropriate guidance law to meet these conditions of missile’ state. Contents of this article are as follows: we analyze these constraints and transform them into the constraints of missiles’ angle of attitude and sight. Then,taking the uncertainty of the missile’s model and parameters into account, we use Variable Structure Control Theory to design midcourse guidance law. Select the appropriate sliding function to realize the control of angle of sight. At the same time, we prove that the midcourse guidance law have a characteristics of limited time convergence. It ensure the stability of the guidance law.Finally, we use MTLAB to simulate the midcourse guidance law under three trajectory, which is close-range, mid-range and long-range. The simulation results show that the midcourse guidance law can meet the multiple constraints we proposed.