Extended differential geometric guidance law with extended state observer

No restrictions are imposed on the motion states of missile and target and the line of sight rotation coordinate system is introduced into the derivation of differential geometric guidance law. Then, the extended differential geometric guidance law is achieved whose scope of application is largely extended. In order to realize the derived law, instead of the complex computation of torsion command, a novel and simple algebraic approach is proposed to directly determining the applied direction of commanded missile acceleration. Furthermore, the target acceleration is estimated on basis of the extended state observer theory, which makes the derived law more applicable to intercepting maneuvering targets in practical engagement scenarios. Simulation results demonstrate that the obtained laws are effective and can fill up the drawback that pure proportional navigation cannot cope with high-speed maneuvering targets inside the atmosphere.