Bias-Shaping Method for Biased Proportional Navigation with Terminal-Angle Constraint

The proposed suboptimal guidance with a terminal body-attitude constraint for reentry vehicles in appears to be the first attempt to design an impact-angle-constrained guidance. In a modified proportional navigation (PN) guidance with a time-varying bias, which is a function of relative range, was proposed using a nonlinear planar engagement and Lyapunov-like function. Although various guidance laws to control the impact angle have been developed so far, most of these laws are difficult to implement, especially for a passive homing missile equipped with an infrared seeker, because an accurate time-to-go estimation or range information is required. Thereafter, BPN with zero bias is implemented during the remaining flight because the bias is no longer needed. The proposed shaping method provides valuable features. First, the method does not require a time-to-go estimation and range information. Second, the method has a simple and feasible structure for implementation because only the line-of-sight rate information is required.