Dynamic geo-fence assurance and recovery for nonholonomic autonomous aerial vehicles

Currently, there exists a growing demand for increased levels of autonomy in many types of aerial vehicles. This is a direct consequence of the need for increased safety and efficiency as the proliferation of these vehicles increases and the airspace becomes more densely populated. In regard to vehicle autonomy, one need relates to constraining the vehicle to a planned flight path that has set tolerances based on safety and the dynamics of the aircraft. In practice, in order to satisfy this need, potential obstacles, restricted regions, and nondeterministic factors that could lead the aircraft to violate the tolerances of the planned flight path must be accounted for. This paper proposes a solution to this problem which extends the concept of a “dynamic geo-fence” in order to provide for a way to first assure that the path constraints are met and, if necessary, recover to the flight path when a violation occurs. Our solution consists of two parts: a static 2-D vector field map and a trajectory planner. The construction of the vector map takes into account the dynamics of the aircraft and the required path constraints and allows for the presence of obstacles whose shape can be either convex or concave. Additionally, the solution was formulated assuming nonholonomic constraints for the dynamics of the vehicle. Methods for construction of the vector map are provided in this work. Simulation results show recovery trajectories in the presence of complex obstacles, including concave and cluttered environments. Limitations and possible improvements of this approach are also discussed.