Qualitative analysis of guidance and control methods for wind gradients exploitation with small fixed wing UAS

In this paper, different Guidance and Control (GC) methods for trajectory tracking are analyzed. This effort considers the ongoing research effort regarding wind features characterization and trajectory generation. The investigation of GC methods is contextualized for long duration missions of small Unmanned Aerial Systems (UAS). These are often hampered by the platform characteristics with cost and weight stringent restrictions. Therefore, innovative ways of increasing flight duration are necessary to fulfill the safety and reliability requirements for such missions fulfilling the cost and weight constraints. Atmospheric Energy Harvesting has been studied as an alternative for flight duration enhancement. The guidance and control strategies have been focused in the dynamic soaring case, in which the trajectories require precise tracking for energy gain. This gain depends on the tracking ability of the autopilot which motivates this analysis. As a conclusion to this analysis, two methodologies are chosen as candidates for GC, one based on pure differential geometry techniques to formulate simple error equations, and the other that uses adaptive control strategies based on vector field theory to formulate error equations and a Lyapunov function ensuring asymptotic stability with complex curve shapes and wind disturbances.