Unmanned aerial vehicle safety bubble simulation results

Title: An Adaptive Six-Layer Safety Bubble for Non-Cooperative UAV Self-Separation Abstract The integration of unmanned aerial vehicles (UAVs) into shared airspace requires on-board safety mechanisms for self-separation without cooperation between platforms or centralised air-traffic services. This paper proposes the UAV Safety Bubble (USB), a six-layer geometric model that defines an adaptive safety envelope around the UAV. Each layer corresponds to a distinct physical contribution: platform dimensions, positioning uncertainty, communication performance, wind disturbance, detection-processing latency, and avoidance manoeuvrability. The model was evaluated through 5,000 Monte Carlo simulation instances across five conflict scenarios, including static-obstacle avoidance, head-to-head encounters, and 90$^\circ$, 30$^\circ$, and 60$^\circ$ approaches between two dynamic UAVs. Platform, sensing, communication, and environmental parameters were sampled from uniform distributions across operational ranges. No instance produced an intrusion into the fifth layer ($USB_{5}$), the model's operational separation boundary. The smallest clearance between the $USB_{5}$ outer edge and the obstacle's centre of mass was 35.36~m, recorded in the 90$^\circ$ approach scenario, and the one-sided 95% upper bound on the per-instance intrusion probability was 0.060%. The adaptive envelope achieved this at per-scenario median route-length overheads of 16-36% relative to nominal straight-line routes. The USB complements downstream planners by providing an adaptive no-go region. The avoidance manoeuvres evaluated are restricted to the horizontal plane; full 3D avoidance is left for future work.