Composition of Safety Constraints For Fixed-Wing Collision Avoidance Amidst Limited Communications

TL;DR

This paper introduces a novel barrier function-based method for fixed-wing UAV collision avoidance, ensuring safety among multiple vehicles with limited communication, validated through simulations of 20 UAVs maintaining safe distances.

Contribution

It develops a new barrier function approach for collision avoidance that works for multiple UAVs, respects actuator limits, and reduces communication overhead.

Findings

Successfully guarantees collision avoidance for two vehicles over time.

Extends to multiple vehicles with safety objectives satisfied simultaneously.

Simulation with 20 UAVs shows effective maintenance of safe distances.

Abstract

This paper considers how to ensure that a system of fixed wing Unmanned Aerial Vehicles (UAVs) can avoid collisions. To do so we develop a novel method for creating a barrier function, which is similar to a Lyapunov function and can be used to ensure that a system can stay safe for all future times. After introducing the general approach, it is shown how to ensure that collision avoidance for two vehicles can be guaranteed for all future times. The construction is then extended to the case of arbitrarily many vehicles by addressing how to satisfy multiple safety objectives simultaneously. We do this while ensuring output actuator commands are within specified limits. Because this formulation requires communication of control values and may therefore reduce throughput of other important messages, we then show how to reformulate the solution without this significant communication overhead while still ensuring safety is maintained and actuator limits are respected. We validate the theoretical developments of this paper in the simulator SCRIMMAGE with a simulation of 20 UAVs that maintain safe distances from each other even though their nominal paths would otherwise cause a collision.