Cooperative Path Following Control of a Team of Quadrotor-Slung-Load Systems Under Disturbances

Abstract

In this paper, we address the challenging problem of path-following control for a group of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> Quadrotor-Slung-Load Systems (QSLSs) subject to time-varying disturbances. A single QSLS consists of a quadrotor vehicle and a load attached to the vehicle's center of mass via a cable. We propose a distributed path coordination framework that generates <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> desired paths for the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> loads while maintaining a fixed inter-load formation pattern. Furthermore, we introduce a robust controller for each of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> quadrotors to drive the respective load along the assigned path. The path-following controller is designed to ensure that the quadrotor thrust remains bounded with respect to position and velocity tracking errors. We present a series of simulation and experimental results to validate the effectiveness of the proposed approach and demonstrate its performance.