System-Level Test Case Generation and Execution for Distributed Cooperative Unmanned Aerial Systems

Systems of cooperating unmanned aerial vehicles (UAVs) can achieve requirements that individual UAVs cannot achieve. Particularly of interest to us are groups composed of UAVs that are cooperating in a distributed way, which would include some types of drone swarms. We refer to these groups as distributed cooperative unmanned aerial systems (DC-UAS). Cyber-physical systems must be tested before operational deployment, and while there has been substantial research into designing DC-UAS capabilities, there is a lack of systematic approaches for generating and executing test cases for system-level verification. Scenario-based testing (SBT) combined with search methods (SBT+search) is an approach that has been used to test autonomous cars and UAVs, but not in the context of distributed cooperative operations. In this paper, we show how the existing SBT+search approach to test an individual UAV can be adapted to conduct system-level testing of a DC-UAS, despite the additional properties inherent to a DC-UAS. Specifically, the adaptation involves incorporating the global task of the DC-UAS and information about the system's individual UAVs into the approach's search process. We then utilize a model of a decentralized drone swarm to concretely demonstrate the adapted approach, resulting in the generation of scenarios that challenge the example system's ability to behave safely and perform global tasks. We also propose additional considerations when formulating the test case generation process. The result is a testing approach for DC-UAS that builds on existing approaches, producing a solution for test case generation and execution through the perspective of system-level verification rather than design.