UAV Swarm Emergency Recovery Failure: Semantic Mismatch Causes GEN_NEW_TRAJ Infinite Loop

Vulnerability Overview This issue highlights a semantic inconsistency in the recovery logic following an Emergency Stop: The Safety Checker uses Euclidean distance and a base pairwise clearance (0.30 m) to determine when recovery planning can begin. The Optimizer uses an ellipsoidal distance model and applies an inflated clearance threshold (1.25 times, i.e., 0.375 m). When another drone is in an emergency stop state (terminal velocity is zero), the optimizer treats it as a permanently stationary obstacle and extrapolates its position based on its terminal state. Since the optimizer’s validation threshold (0.375 m) is stricter than the Safety Checker’s threshold (0.30 m), recovery trajectories consistently fail during the final validation. The system lacks retry limits, fallback mechanisms, or alternative recovery states, causing the FSM to loop infinitely in the state. Scope of Impact Two drones may stop simultaneously during emergency handling and fail to resume motion. The Safety Checker determines that recovery planning can begin, but the optimizer rejects all recovery trajectories due to its stricter constraints. As a result, the two drones may remain stationary indefinitely, repeatedly executing recovery planning that always fails. Remediation (Suggested) 1. Unify Semantics: Align the distance model, clearance semantics, and trajectory validity rules used by the Safety Checker and the Optimizer. 2. Add Escape Mechanisms: Implement escape mechanisms for recovery trajectories, such as deterministic yielding priorities based on drone ID, or escaping from the initial unsafe configuration. 3. Log Key Metrics: Log the minimum ellipsoidal distance, conflicting drone IDs, and failures when the optimizer rejects trajectories. 4. Add Global Retry/State Failure States: Add global retry limits, fallback mechanisms, or explicit / states for recovery planning failures. 5. Note: The amplification factors of 1.5 and 1.25 may be intentional by design; the core issue is the semantic inconsistency among emergency recovery, safety checking, and trajectory optimization. Key Code Snippets Swarm Clearance Configuration (XML): Safety Checker - Trajectory Timing: Optimizer - Ellipsoidal Distance Model: Optimizer - Extrapolation of Stale Trajectories: Final Validation Threshold Calculation: Unbounded Recovery Retry Logic: Recovery Planning Initial State: Retry Loop:

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UAV Swarm Emergency Recovery Failure: Semantic Mismatch Causes GEN_NEW_TRAJ Infinite Loop

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