Concept for Sensor and Processing Equipment for Optical Navigation of VTOL during Approach and Landing

Recent progress in the development of UAV concepts especially for autonomous operation and urban mobility increases the necessity for reliable, precise and robust navigation. While coupled GNSS and INS systems have proven to be able to provide the required level of accuracy, they alone are not sufficient during final approach and landing due to limited integrity monitoring capabilities. Using an independent optical navigation solution to validate the INS/GNSS based position is an approach that has already proven to enable conventional aircraft to perform autonomous landings on runways without the need for ground based equipment. However, while some of the fundamental aspects of such a navigation system can be derived from the conventional aircraft application, many aspects need to be adapted to the unique behaviour and flightpaths of VTOLs -one of those being the sensor and processing equipment concept. This paper proposes a full stack sensor concept, consisting of multiple color and infrared cameras, GNSS/INS sensors, a radar altimeter and processing equipment, that is capable of reliably identifying landing site markings from the required distance, optically track those markings until right before touchdown and use that information to generate a reliable navigation solution allowing the aircraft to perform autonomous landings.