UAV powertrain efficient design through a modelbased approach

The wide spreading market of unmanned aerial vehicles (UAVs) is requiring more and more performing flying platforms. For rotary wing systems, especially multicopters, the leading design challenge is the powertrain, typically composed (for mini and small UAVs) by: battery, electronic speed controllers, electrical motors and propellers. A strong knowledge in terms of these subsystems behaviour in their operative conditions is required. Therefore, through a careful design and modelling of these subsystems, it is possible to achieve higher overall efficiency, lighter systems, and consequently, an increased flight endurance. Unfortunately, current literature and available datasheets on UAV components, especially electric motors and propellers, are scattered and not reliable. The present work proposes a model-based design methodology: motor and propeller equivalent analytical models are presented; then – in order to identify model parameters, tune them and shade some doubts about the reliability of available data – two test benches have been developed. The first one allows to characterize the electric motors varying the torque load condition, while the second is devoted to propellers thrust and torque characterization. Models and identified parameters have been validated by comparing the expected results with in-flight endurance experiments.