# Structural Vibration Analysis of UAVs Under Ground Engine Test Conditions

## TL;DR

This paper presents a low-cost system for analyzing UAV vibrations during ground tests, helping detect structural issues and improve safety.

## Contribution

A portable, integrated vibration analysis system for UAVs using Raspberry Pi and DAQ hardware is introduced.

## Key findings

- The first and second wing bending natural frequencies were identified at 12.3 Hz and 17.5 Hz.
- Vibration amplitudes are highest at the wingtips and near the engine.
- A 23 Hz subharmonic was detected, related to the propulsion system's 45 Hz excitation frequency.

## Abstract

Monitoring mechanical vibration is crucial for ensuring the structural integrity and optimal performance of unmanned aerial vehicles (UAVs). This study introduces a portable and low-cost system that enables integrated acquisition and analysis of UAV vibration data in a single step, using a Raspberry Pi 4B, data acquisition (DAQ) through a MCC128 DAQ HAT card, and six accelerometers positioned at strategic structural points. Ground-based engine tests at 2700 RPM allowed vibration data to be recorded under conditions similar to those of real operation. Data was processed with a Kalman filter, a Hann window function application, and frequency analysis via Fast Fourier Transform (FFT). The first and second wing bending natural frequencies were identified at 12.3 Hz and 17.5 Hz, respectively, as well as a significant component around 23 Hz, which is a subharmonic of the propulsion system excitation frequency near 45 Hz. The results indicate that the highest vibration amplitudes are concentrated at the wingtips and near the engine. The proposed system offers an accessible and flexible alternative to commercial equipment, integrating acquisition, processing, and real-time visualization. Moreover, its implementation facilitates the early detection of structural anomalies and improves the reliability and safety of UAVs.