Design of missile guidance law subject to acceleration command constraint

Based on target-missile relative motion equation in plane, a two-dimensional guidance law subject to acceleration command constraint is designed using command filtered backstepping approach, and the second-order dynamics characteristics of missile autopilot is considered. The guidance system is divided into two sub-systems in the light of stability requirement of the main states. Then the command filtered backstepping approach is used to design the guidance laws for two sub-systems based on the principles of zeroing line-of-sight (LOS) angular rate and letting the relative velocity between missile and target be less than a negative constant, respectively. The command filtered backstepping approach can not only address saturation constraint on acceleration command but also overcome the deficiency of "explosion of terms" in the conventional backstepping method. Finally, the simulations are performed for controlling and non-controlling along LOS in the case of acceleration command saturation and missile autopilot with big lag. The results show that the guidance law has excellent performance for intercepting a highly maneuvering target.