Guidance law with angular constraints for head-pursuit or head-on engagement

For head-on or head-pursuit engagement,angle control proportional navigation( ACPN) and angle control retro-proportional navigation( ACRPN) closed-form trajectory shaping guidance law with impact angular constraints were proposed,which were based on proportional navigation( PN) or retro-proportional navigation( RPN) guidance law. ACPN with positive navigation ratio intercepted targets in head-on engagement,whose advantages were using less control efforts and final acceleration. ACRPN with negative navigation ratio intercepted targets in head-pursuit engagement. ACRPN's control efforts,miss distance and impact angle error were much less than that of guidance law in head-on engagement. Simulations demonstrate these claims mentioned above. Besides,the capture regions of ACPN and ACRPN for interception of high-speed targets are analyzed,which indicates that ACPN's capture region is larger than that of bias PN. Moreover,ACPN should be used to intercept targets in head-on engagement when the gimbal angle is less than sum of initial line-ofsight angle and 90°,and ACRPN should be used in head-pursuit engagement for the gimbal angle is equal to or greater than sum of initial line-of-sight angle and 90°.