Gain-Scheduled LQR for RLV during In-Air Capturing: Trajectory Tracking, Recovery Limits and Replanning Criteria

Kurzfassung

‘In-Air Capturing’ is a unique launcher recovery approach in which a winged stage is retrieved mid-air by a towing aircraft, eliminating landing fuel requirements and increasing payload capacity. The method requires precise maneuvering of the reusable launch vehicle (RLV) relative to the aircraft to enable successful connection by a tethered capturing device despite external disturbances. This paper presents a guidance and control framework using a gain-scheduled Linear Quadratic Regulator (LQR) that adapts to the RLV’s energy state for optimal performance. The controller guides the RLV into a wake-free ‘mating zone’ behind the aircraft for safe docking. Performance is evaluated under nominal conditions, disturbances, and initial state offsets. Capture feasibility is assessed through a Monte Carlo campaign, and the number of viable capture attempts is estimated.