Комбіноване акустико-тепловізійне донаведення автономних дронів-перехоплювачів на малошвидкісні повітряні цілі типу Shahed-136

Abstract

This article addresses the critical vulnerability of traditional air defense systems to mass-produced, low-speed kamikaze UAVs like the Shahed-136 (Geran-2). These targets operate at low altitudes (50–150 m) and have minimal radar signatures (RCS < 0.1 m²), making them difficult and expensive to intercept with standard missile systems. The research provides the first stage of a general methodology for guiding interceptor drones via passive physical fields, focusing on a fully passive, low-cost, and EW-resistant solution.  The methodology involves a comprehensive analysis of the target's acoustic and thermal signatures. The acoustic field of the Shahed-136’s MD-550 engine is characterized by a deterministic spectral structure, including the shaft frequency 75–100 Hz), blade passing frequency (BPF), and cylinder firing frequency. For reliable detection, Infineon IM73A135 MEMS microphones are selected due to their high signal-to-noise ratio (SNR), providing a calculated margin of over 25 dB at a range of 1 km. The thermal channel utilizes uncooled Long Wave Infrared (LWIR) sensors with a sensitivity (NETD) of 25 mK to track the heat signature of the engine at distances under 500 m. A key scientific novelty of this work is the formally specified three-phase Finite State Machine (FSM) architecture. This system dynamically manages the transition between three states: acoustic search (long-range), hybrid tracking (mid-range), and LWIR-based thermal homing (terminal phase). Adaptive weighting algorithms for sensor fusion are proposed to ensure stability during "thermal crossover" periods or in high-noise environments. Furthermore, the study substantiates the use of Proportional Navigation (PN) with a constant N=4. Analytical calculations confirm that this approach reduces energy consumption by 40% while increasing interception probability compared to pure pursuit methods. For a standard 7-inch FPV interceptor, the required commanded acceleration remains within a physically achievable limit of 2.4 g.  The projected results indicate an 82% probability of target acquisition at distances of 2–4 km and a high resistance to electronic warfare (approximately 95%) due to the system's complete passivity. This research provides a foundational framework for cost-effective, non-kinetic additions to layered air defense systems, particularly effective against GNSS-independent autonomous platforms.