Energy efficient multicopter flight scales with vehicle mass
Mass Scaling Laws for Energy-Optimal Horizontal Multirotor Flight
Robotics
Summary
Flying multicopters with varying weights affects how much energy they use, especially when carrying different loads. The authors found simple math rules that predict the most energy-efficient flying speed and angle based on the multicopter’s weight. Their experiments with real drones confirmed that heavier drones should fly faster for the best energy use and that the best flying angle doesn't change with weight. This helps plan flights that use less battery power and last longer.
What this means in practice
- •For drone delivery operators: Adjust cruise speeds automatically based on payload weight to maximize flight range for package delivery drones.
- •For environmental monitoring teams: Optimize drone flight plans to conserve energy when carrying different sensor loads during long aerial surveys.
Authors
Ayush Patnaik, Nicolas Michel, Leonard Baursfeld, Davide Scaramuzza, Xinfan Lin
Abstract
Multicopters are a type of aerial robot seeing extensive real-world applications but with range and endurance as critical bottlenecks. Optimization of its energy efficiency through energy-aware flight planning (e.g. cruise speed-scheduling) has hence been an important topic. The mass of the multicopter is an important factor to consider, as it has a significant impact on efficiency, and many common applications are subject to frequent mass variation due to payload change. This work derives closed-form scaling relationships between the energy-optimal steady horizontal flight behavior of a multicopter and its vehicle mass, and validates them experimentally on two multirotor platforms. Specifically, for mass-only variation, i.e., when payload changes the vehicle mass while the airframe geometry, aerodynamic characteristics, and rotor configuration remain unchanged, we show through a combination of numerical simulation, theoretical derivation, and experimental validation that (1) the energy-optimal velocity is proportional to the square root of vehicle mass; (2) the energy-optimal pitch angle is constant with respect to mass; and (3) the optimal energy per meter is proportional to mass. The analysis shows that these three relationships arise from a common mass-similarity property of the steady-state flight and rotor-aerodynamic equations. Furthermore, the obtained scaling relationships enable simple yet effective cruise-speed planning to optimize energy efficiency and extend the range and endurance of the multicopter.