Lateral entry guidance with no-fly zone constraint

Abstract

No-fly zones are geographic constraints for the atmospheric entry flight. Two lateral guidance methods are presented for the entry flight constrained by multiple no-fly zones. The first method employs a dynamic heading corridor to control the vehicle's velocity heading angle. The corridor is generated based on a chain mode strategy that takes heading limits for all the no-fly zones and the target into account. The dynamic corridor is adaptively updated during the flight according to the vehicle's state and the actual constraints. The second method is designed based on a waypoint vector which is located between each pair of no-fly zones. This waypoint vector contains both the location and the direction constraints for the flight trajectory. The vehicle is capable of flying the avoidance trajectory by passing through one or more expected waypoints in specified directions. The two guidance methods are finally tested in four entry missions constrained by various no-fly zones. Results indicate that these methods are effective for no-fly zone avoidance missions in both the nominal and dispersed cases.