Cooperative Transportation of UAVs Without Inter-UAV Communication

TL;DR

This paper presents a novel leader-follower UAV transportation system that operates without inter-UAV communication, using real-time trajectory modification and force estimation to adapt to dynamic environments.

Contribution

It introduces a communication-free cooperative transportation method with real-time trajectory updates and force estimation using UKFs, validated through simulations and experiments.

Findings

Effective real-time payload tracking demonstrated in simulations.

Successful real-world UAV experiments with acceptable tracking errors.

System robustness affected by airflow disturbances in confined spaces.

Abstract

A leader-follower system is developed for cooperative transportation. To the best of our knowledge, this is the first work that inter-UAV communication is not required and the reference trajectory of the payload can be modified in real time, so that it can be applied to a dynamically changing environment. To track the modified reference trajectory in real time under the communication-free condition, the leader-follower system is considered as a nonholonomic system in which a controller is developed for the leader to achieve asymptotic tracking of the payload. To eliminate the need to install force sensors, UKFs (unscented Kalman filters) are developed to estimate the forces applied by the leader and follower. Stability analysis is conducted to prove the tracking error of the closed-loop system. Simulation results demonstrate the good performance of the tracking controller. The experiments show the controllers of the leader and the follower can work in the real world, but the tracking errors were affected by the disturbance of airflow in a restricted space.