Gain Scheduling Based PID Controller for Fault TolerantControl of Quad-Rotor UAV

In this paper, in view of the advantages of widely used Proportional-Integral-Derivative (PID) controller and gain scheduling control strategy in aerospace and industrial applications, a control strategy by using gain scheduling based PID controller is proposed for fault tolerant control (FTC) of a quad-rotor Unmanned Aerial Vehicle (UAV). The nonlinear dynamic equations of motion of the quad-rotor UAV are firstly derived based on the Newton’s second law. PID controllers under fault-free and several different fault situations are then designed and tuned to control the quad-rotor UAV model under normal and different faults flight conditions. Each PID controller uses the speed and the orientation of each propeller for stabilizing and hovering motion of the quad-rotor UAV. Based on a decision variable (used as scheduling variable in this case) associated with a fault detection and isolation module, switching of each pre-tuned PID controller can be made in real-time and on-line. Simulation results under different fault scenarios have shown the effectiveness of the proposed approach for a six-degree-of-freedom nonlinear quad-rotor UAV model.