Adaptive proportional guidance law for reentry vehicles with impact angle and terminal velocity constraints

Adaptive proportional guidance law is studied during the reentry phase of vehicle, considering terminal velocity and impact angle constraints. 3-D adaptive proportional guidance law satisfying impact angle constraint is derived, guidance equations are expressed in longitudinal and lateral plane respectively, needed guidance command of angle of attack and sideslip angle is generated. Guidance command of angle of attack and sideslip angle is appended when considering reentry velocity. Synthesized guidance command is the sum of needed guidance command and appended guidance command. Effect of attitude control for vehicle is compared using optimal guidance and adaptive proportional guidance law, the attitude of vehicle is stable and the vehicle is guided to target point using adaptive proportional guidance laws. Trendline of landing error, reentry velocity and terminal angle varying with target velocity are analyzed, adaptive proportional guidance law performs much better than optimal guidance, simulation results indicate that adaptive proportional guidance law is robust to maneuvering target.