Unmanned Aerial Vehicles: Embedded Control

Chapter 7

Improving Attitude Stabilization of a Quad-Rotor Using Motor Current Feedback ¹

7.1. Introduction

We have witnessed in the last few years that the applications of autonomous mini-aerial vehicles have significantly increased. However, all the applications strongly depend on the fact that the attitude of the aerial vehicle is satisfactorily stabilized. Indeed, if the pitch and roll angles are not controlled with a high degree of precision, drift will result and the UAV (unmanned aerial vehicle) will move away from its desired position. In this chapter we propose an original method that effectively improves the attitude stabilization performance. The technique uses low cost components and is based on motor armature current feedback. This technique results in a controller that is robust with respect to external perturbations as has been observed experimentally.

There are few studies with respect to the improvement of the attitude stabilization for aerial vehicles. Most of the main results have been developed for spacecraft such as satellites [WER78]. In [LIM03, ROT 08] the authors proposed a methodology for improving attitude stability using a momentum wheel in a four rotor dual-spin vehicle. Another approach is presented in [JAR 08], where the authors propose a sensor fusion technique in order to improve the attitude of a UAV. The approach is based on an extended Kalman filter using the information coming from an IMU (inertial measurement unit) and a global positioning system ...