Intelligent Wind Compensated Small UAS Flight Planning

Abstract

This document covers the intelligent positioning of waypoints to improve flight path navigation for an Unmanned Aircraft System (UAS) in windy conditions. These conditions present a situation that makes navigation particularly difficult for UAS. A solution that allows for more precise aircraft position control without requiring the re-writing of internal navigation logic is desired. Typically, UAS flight plans are made using waypoints in which flight lines are formed between sequential waypoints. These flight lines represent the path the UAS will try to follow but are not necessarily where the aircraft will actually go, especially in the presence of wind. In many UAS missions the location and ground track of the flight system is of the utmost importance. Incorrect positioning of the UAS can result in missed opportunities to collect necessary data. It is crucial for the internal pilot (the person controlling the UAS from the ground during autonomous flight) to plan each mission such that the aircraft is in the correct position at all times to allow for maximum sensor effectiveness. A method to enhance flight plan tracking without rewriting a commercial autopilot's tracking logic is desired. First, a standard flight plan is used to characterize the autopilot's base performance with the applied configuration settings. Next, flight simulations and aerodynamic models are used to determine the aircraft's flight capabilities, then a closedform analytical solution is derived based upon aircraft flight dynamics and performance. This algorithm determines precise waypoint locations for improved navigation for various flight plans. Finally, wind compensation is incorporated into the algorithm using vector mathematics. The result of intelligent flight planning is an improvement in flight line tracking for typical flight paths, with and without wind present. Intelligent flight plans create improved ground tracks that more closely resemble the flight plan. In comparison, standard flight plans can produce ground tracks that are drastically different than the programmed flight plan, particularly in windy conditions. The improvement provided by intelligent flight planning is illustrated in the form of increased time on the flight paths and decreased path error, in both simulation and flight testing.