Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
On the modeling of an UAV flight formation for aerial transportation
Submission Author:
Renan Silva , São Paulo
Co-Authors:
Renan Silva, Douglas Bueno, Rodrigo Borges Santos
Presenter: Renan Silva
doi://10.26678/ABCM.COBEM2023.COB2023-1467
Abstract
The multirotor configuration of Unmanned Aerial Vehicles (UAVs) is gaining relevance due to its relative ease of use in various applications, such as border surveillance, crop spraying, and aerial transportation. In particular for aerial transportation, the use of a single multirotor in an aerial transportation mission is usually limited by their low endurance and small payload capability. On the other hand, using a formation flight with multiple vehicles collaboratively transporting a suspended payload, the weight is distributed among the vehicles such that each vehicle operates within its operational envelope, allowing the transportation of heavier payloads. The present work presents the dynamic of an UAV formation transporting a payload exceeding the limits from a single vehicle. The payload is attached to each UAV using an inelastic rod. Then, the dynamic equations of motion for this multi-lift system are obtained in terms of the original coordinate space. The resulting differential and algebraic equations are then transformed into a system of ordinary differential equations through an index-reduction procedure, and the accelerations from the constraint equations are modified to obtain a numerically stable integration in the time domain. A leader-follower controller with virtual constraints is used so that vehicles fly in a formation. This goal is achieved by modifying the follower's outer-loop to use the leader position as a reference, then, they compute their control based on the desired formation geometry and the relative distance with respect to the leader position. The formation controller reference model includes the suspended payload as an equivalent disturbance force. The trajectories show the leader accurately tracking the mission trajectory whereas the followers reasonably keep the desired formation. However, the UAVs are pulled in the direction of the payload, resulting in an increasing position error because the formation controller design does not account for the additional payload weight. This effect is verified until the system achieves an equilibrium condition in which the closed-loop force introduced by the positioning error in the formation controller balances the constraint force exerted by each UAV. The presented results demonstrate that the proposed approach is an interesting modeling for describing a multi-rotor UAV flight focused on aerial transportation in flight formation.
Keywords
UAVs, Flight Formation, control
