Unmanned Aerial Vehicles: Embedded Control

Chapter 8

Robust Control Design Techniques Applied to Mini-Rotorcraft UAV: Simulation and Experimental Results ¹

8.1. Introduction

The study and development of unmanned aerial vehicles (UAVs) has matured over recent years due to the fact that they can be used in a wide variety of applications, ranging from environmental monitoring in civil applications to surveillance and homeland security in military applications. Hovering platforms have the operational flexibility of being able to take off vertically, hover and land vertically, but they usually have limitations in forward flight, such as low speed and poor endurance. Regardless of its limitations, rotorcrafts have been used in many applications. Also, automatic hovering rotorcrafts represent an important challenge in control science.

We are interested in the stabilization problem of a mini-rotorcraft with four rotors using a robust control strategy. The proposed platform for results validation is shown in Figure 8.1. Several approaches to the control of a mini-rotorcraft can be found in literature, e.g. in [CAS 04] a nonlinear control based on nested saturations is presented. In this approach, the dynamics is decoupled into lateral and longitudinal dynamic systems. Thus, nested saturation control was used to stabilize each system. In [LAR 06], the authors propose a robust linear PD controller considering parametric interval uncertainty. Here, the authors present a robust stability analysis and calculate the robustness margin ...