Non-Linear Control System for Uavs

Non-Linear Control System for Uavs

Abstract

In this work we consider the attitude control problem. We present a robust, almost global, non linear attitude controller based on Lyapunov functions. It is shown to be ro- bust against unmodeled perturbations induced by aerodynamic or random perturbations, and against perturbations induced by noisy or faulty attitude and angular measurements used to compute the control action. Then, bounds on the maximum sample time for the discrete time (digital) implementation of the controller are found using Sample and Zero Hold analysis. The bounds and the minimum attainable error are found to depend on the choice of gains for the controller. This relationship is explored and bounds on the sample time are found in terms of the bounds used for robustization. From this rela- tionship, gains to achieve the desired error and sample time performance can be found. Simulations are carried out to demonstrate the results on a quadrotor UAV. From a systems engineering point of view, these results allow for higher level requirements in attitude and angular velocity to be translated into lower level requirements on the digital controller and the navigation subsystem as timing and error performance requirements respectively.

Publication
Non-linear Control System for UAVs
Date