Characterization of the Aerodynamic Ground Effect and Its Influence in Multirotor Control

Received Feb 14, 2017; Revised Jul 6, 2017; Accepted Jul 13, 2017

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1. Introduction

In the last years, there has been a growing interest in Unmanned Aerial Vehicles (UAVs) [1]. UAVs of different sizes have been used in applications such as exploration, detection, precise localization, monitoring, and measuring the evolution of natural disasters. However, in most of these applications, the aerial robots are mainly considered as platforms for environment sensing. Then, the aerial robots do not modify the state of the environment and there are no physical interactions between the UAV and the environment. Furthermore, the interactions between the UAVs themselves are essentially information exchanges, without physical couplings between them.

Recently, the development of autonomous aerial robots with integrated robotic manipulators is catching much interest in robotic research [2, 3]. These aerial manipulators [4–6], as they are usually known, extend the range of possible applications of UAVs. For instance, aerial manipulators can be used for the inspection and maintenance of industrial plants and infrastructures [7], aerial power lines, and moving objects [8] and taking samples of material from areas that are difficult to access.

Aerial robotic manipulation with multirotors usually involves flying near objects, structures, and other obstacles, for example, to grasp or manipulate objects that are on the ground, over surfaces, near walls, or even under a surface. In all these cases, the multirotors will operate in hover or low speed near these horizontal or vertical surfaces. This paper studies the control of multirotor platforms under the influence of close ground surfaces on multirotors rotor thrust. Thus, for example, in the AEROARMS European project [9], aerial manipulators with multiple arms are used for inspection and maintenance in industrial settings and flying close to horizontal surfaces, and in the ARCAS European project [10], aerial robotic manipulation for assembly over a surface is considered (see Figure 1).

[figure omitted; refer to PDF]

The wake of a rotorcraft can be...