Modeling and validation of electric multirotor unmanned aerial vehicle system energy dynamics

Electric Vertical-Take-Off-and-Landing aircraft has been emerging as a revolutionary transportation mode. A major limiting factor for unmanned and manned applications is the energy performance, which determines the flight time and range. Characterization and modeling of the underlying multi-physical dynamics is critical for the efforts on design, motion planning, and control to improve the energy performance, which often take a model-based approach. A system-level model incorporating all relevant subsystem dynamics and their coupling is missing in literature. To fill this gap in the state of art, we develop such a model by integrating sub-models of various physical dynamics, including the aerodynamics of the rotor-propeller assembly, electro-mechanical dynamics of the motor and motor controller, electrical dynamics of the battery, and rigid body dynamics of the airframe. The model is capable of capturing critical system variables and their mutual impacts during flight, and has been parameterized and validated by both component and vehicle experiments. Based on the model, we demonstrate the importance and necessity of incorporating individual dynamics into model-based planning and control, by highlighting the impact of battery dynamics on the propulsion performance, the influence of rotor (inflow) aerodynamics on the optimal cruising velocity, and the breakdown of vehicle energy efficiency to each subsystem dynamics.