Cooperative motion control of a formation of UAVs

Abstract

The recent advances in electronics and communication networks have aroused interest in the research community towards cooperative motion control of multiple autonomous robotic vehicles. There are many scenarios where employing a fleet of small, scalable and inexpensive vehicles is more attractive than using a single expensive robot. In the literature the topic is addressed for mobile robots, autonomous underwater vehicles (AUVs), autonomous surface vehicles (ASVs), autonomous aerial vehicles (UAVs) and other robots. Specifically, the formation of UAVs is an asset, as the UAV technology grows stronger in society. In this dissertation we address cooperative motion control problem for UAVs that unravels in two tasks: path-following and coordination control. The former requires the vehicle to converge and follow a desired path with no temporal constraints. The latter coordinates the elements in a fleet to travel on a desired pattern. The strategy adopted for the path following unfolds the problem in a geometric and speed assignment task. The vehicle is permanently following a virtual target point (VTP), which moves on the desired path. Adjusting the speed of the target, synchronization is accomplished. Nonlinear techniques enable to explicitly take into account the nonlinearities inherent to the model. Graph theory describes the inter-vehicle communication topology. In order to validate the adopted strategies, a guidance, navigation and control (GNC) evaluation environment for Flight Variables Management System (FVMS) is developed. The tool, herein developed, may be as well used to evaluate other GNC algorithms in a reliable manner. Numerical simulations and software-in-the-loop (SiL) data evaluate the methods addressed. The results show that the nonlinear Lyapunov based control law proposed correctly solves the path following problem. The performance is comparable to other wellestablished solutions. Moreover, coordination in a switching topology communication is achieved.