A ROS package for UAV run time assurance with in-the-loop reachability

C. Llanes, S. Coogan
AIAA SCITECH 2023 Forum, 2023


This work describes an open source software package for run time assurance (RTA) of UAVs to verify safety in the form of collision avoidance. An operator designs a primary controller with possible learning-enabled components or with human inputs. Learning-based control design is inherently unverified and the RTA supervises the control behavior during the learning process. The proposed RTA package guarantees collision avoidance of obstacles while acting as a supervisor for an operator's primary controller. The RTA mechanism uses control barrier functions (CBFs) with reachability analysis of the UAV dynamics to detect unsafe control actions from the primary controller and solves an optimization problem to minimally adjust desired control inputs to ensure that collision-bound trajectories are avoided. We use the Robot Operating System (ROS) middleware as a framework for designing the software package. We describe the main underlying algorithm and its implementation as a ROS2 package, and we demonstrate its use in hardware experiments.