Navigation aware planning for tandem UAV missions in GNSS challenging environments

This paper discusses the problem of autonomous UAV missions in GNSS-challenging environments. A cooperative navigation approach is proposed where autonomous flight of a ("son") UAV in challenging environments is supported by a cooperating ("father") aircraft flying under good satellite coverage, by means of relative sensing and information broadcast. It is assumed that flight plan for the son UAV does not take navigation issues into account and only depends on mission constraints. Thus, the paper is focused on path planning for the father UAV, and its main purpose is to define a flyable trajectory for the father that allows maximizing the accuracy in son positioning estimation when cooperative measurements are used to overcome the lack of GNSS reliable measurements. The concept of generalized dilution of precision is exploited to this aim. Son and father paths are divided into a discrete number of intervals where relative geometry can be kept constant, and father path is then optimized to provide the requested geometries. Transitions between subsequent intervals are designed taking dynamic constraints into account. Simulation results, obtained integrating Matlab and Robot Operating Systems software environments, demonstrate that proper optimization of father trajectory improves cooperative navigation performance.