Unmanned Air Vehicle (UAV) regulatory frameworks are progressing to where autonomous flight and operations Beyond Visual Line-Of-Sight (BVLOS) are a possibility, thus driving the need for reliable navigation services to complement or act as a back-up to existing ones (chiefly Global Navigation Satellite Systems (GNSS)). Trusted Position, Navigation and Timing (PNT) solutions must be developed to help tackle the challenges that congested airspace brings, such as the safety of autonomous flight in populated areas or avoiding inflight collisions. Such systems will require reliable position and route information for decision making and for communicating information to the UAV, in a timely manner and with reliability.
Different techniques can be used as alternatives to GNSS for positioning. These techniques generally use signals which are not specifically designed to derive PNT position accuracy or position integrity: these are so-called Signals-of-Opportunity (SOOP). It is feasible that Aeronautical Radionavigation Service (ARNS) signals can be used as SOOP. To use ARNS signals in safety-critical UAV, a certain level of trust in the PNT solution should be guaranteed (integrity) and be provided with timely alerts when thresholds are exceeded.
As part of ESA’s Navigation Innovation and Support Programme (NavISP), the “Robust Navigation of Airborne Autonomous Systems with Carrier Phase of ARNS Signals” (RAASPAS) project aims to develop innovative and reliable Alternative PNT concepts based on ARNS signals and telecommunication SOOP hybridised with traditional navigation sensors, providing UAV users with a positioning solution and an integrity measure, complementary to GNSS. It will validate the proposed Alternative PNT concepts by means of a prototype, benchmarking this against legacy systems.
In partnership with project sub-contractor, Cranfield University, the project goals are to develop new algorithms, software and hardware, to evolve the RAASPAS concept to a viable component of resilient PNT for UAVs in an ever-increasing safety-critical and crowded environment.