Close Enough for Comfort – Analysis of Landing Zone Evaluations with Autonomous No-Hover Landing in Unprepared Locations

The National Research Council of Canada is conducting a multi-year autonomous flight systems research and technology development project entitled Advanced Autonomy Systems for Challenging ENvironments Development & Demonstration (AASCEND). As part of AASCEND a no-hover landing capability has been developed and demonstrated in a variety of environmental conditions, including in limited degraded visual environment (DVE) operations. This paper discusses the requirements for no-hover landings, their value within an Autonomous Flight System (AFS), and the implementation of this capability in the NRC's AASCEND autonomous flight system. It presents a methodology for identifying a no-hover landing envelope, taking into account the complex maneuvering required. Within that methodology a proposed set of assessment criteria for no-hover landing performance and behaviour is introduced. The paper reports on the results of applying this methodology to the AASCEND no-hover landing algorithm in a simulation study, along with associated Landing Zone Evaluation (LZE) system performance requirements.