Modeling and efficiency analysis of bird-inspired flapping-wing aerial vehicle propulsion system

The aerodynamic and inertial loads of Bird-inspired Flapping-wing Aerial Vehicles (BFAVs) exhibit significant fluctuations, leading to pronounced coupling effects among components within the propulsion system. These effects pose challenges to accurate power and efficiency analyses. To address this issue, a comprehensive simulation model of the propulsion system was established, which includes the battery, Electronic Speed Controller (ESC), Brushless DC Motor (BLDCM), and drive mechanism. Unlike prior studies, this model accounts for the efficiency characteristics of both ESC and a complex spatial drive mechanism generating flapping-twisting motion. Numerical solutions for the propulsion system model are obtained using the Runge-Kutta-Fehlberg 4th-5th order method, followed by Sobol’ global sensitivity analysis of overall system efficiency via a developed Kriging surrogate model. This study identifies the main factors that influence the propulsion system’s overall efficiency. Also, the findings demonstrate a maximum improvement of 10.52% in flapping frequency prediction accuracy compared to the model that neglects ESC efficiency and battery characteristics. The BLDCM dominates power loss, accounting for 32.85% of the battery output power at a 60% throttle setting. The model developed in this study more closely reflects reality and provides theoretical support for designing high-efficiency propulsion systems for BFAVs.