CONCEPTUALIZATION OF A PILOT-SCALE TEST RIG FOR THE VALIDATION OF A VIBRATION-BASED CONDITION MONITORING APPROACH FOR EARLY FAULT DETECTION IN DRONE ELECTRIC MOTORS BEARINGS

This thesis addresses the reliability of Brushless DC (BLDC) motors utilized in industrial heavy-lift Unmanned Aerial Vehicles (UAVs). Specifically, the objective of this study is the conceptual design and subsequent development of an operational pilot-scale test rig. This simplified setup is engineered to acquire preliminary experimental data, which is post-processed using vibration-based Condition Monitoring (CM) indicators and spectral analysis techniques aimed at the early detection of motor bearing defects. The proposed concept provides a baseline to investigate the vibrational signature of BLDC motors under constant and variable speed regimes, subject to predefined load conditions, as well as to validate the selected Condition Monitoring approach prior to investing time and resources into more sophisticated designs. The research begins with a contextual analysis, followed by a benchmarking of classical CM indicators used in vibration analysis, thereby establishing the data processing methodology. Subsequently, an analytical model of the rotor shaft is developed; based on the required motor thrust, this model estimates the axial and radial loads acting on the bearings and approximates the geometrical constraints of the installed components. The systematic design approach by Pahl and Beitz is then applied to map the system requirements and define the characteristics of the initial concept. Based on these results, virtual prototyping is performed using Autodesk Inventor, coupled with Finite Element Method (FEM) analyses in Ansys. This allows for a preemptive estimation of the system's natural frequencies and structural stresses, culminating in the realization of the first operational prototype. Preliminary vibration data was successfully acquired and will be analyzed using MATLAB. These data evaluate the motor's dynamic behavior and allow for a comparison between two test rig configurations: with and without elastomeric isolators (silent blocks). Specifically, tests were conducted with an attached propeller at constant speeds and various setpoints. Furthermore, bump tests were performed on both configurations to conduct an experimental modal analysis. This experimental data will be correlated with the FEM results to investigate the influence of the test rig structure.