Analysis of Intentional Electromagnetic Interference Effects on PWM Command Interpretation in UAV BLDC Motor...

Area of Science:

• Electrical Engineering
• Electromagnetics
• Control Systems

Background:

• Multirotor unmanned aerial vehicles (UAVs) utilize electronic speed controllers (ESCs) to interpret pulse-width modulation (PWM) signals for motor control.
• The flight-controller-to-ESC communication pathway presents a physical-layer vulnerability to intentional electromagnetic interference (IEMI).

Purpose of the Study:

• To perform a mechanism-based analysis of IEMI attacks causing motor stoppage in UAV brushless DC motor controllers.
• To develop and experimentally validate a timing-error model for IEMI susceptibility in ESCs.

Main Methods:

• Developed a timing-error model analyzing sinusoidal disturbances on PWM lines affecting ESC edge detection.
• Experimentally characterized IEMI susceptibility on five commercial ESCs using conducted and radiated injection methods.
• Investigated the influence of PWM cable length and coupling response on ESC vulnerability.

Main Results:

• Identified significant variations (over an order of magnitude) in IEMI susceptibility thresholds across different ESCs.
• Demonstrated that both PWM cable coupling response and ESC input-path transfer function shape disturbance propagation.
• Observed that susceptible frequencies shift with PWM cable length due to transmission-line resonance, indicating joint ESC-cable susceptibility.

Conclusions:

• UAV ESCs are susceptible to IEMI-induced motor stoppage through disturbances on PWM signals.
• ESC susceptibility is not an intrinsic property but a result of the combined design of the ESC and its associated PWM cable.
• Further research on shorter, deployment-realistic cable lengths is crucial for understanding real-world IEMI risks in UAVs.