Research On Adaptive Fault-tolerant Control Design For A Quad-rotor Attitude System

Quad-rotor helicopter is a multi-rotor aircraft with a simple structure, and can take-off and landvertically. In modern society, it plays an increasingly important role. However, due to its attitudecontrol system with strong coupling, overdrive and other complex characteristics, it is extremelysensitive to external interference and prone to failures. Therefore, the fault-tolerant control ofquad-rotor attitude system has become a research hotspot in recent years. This thesis, aiming atstudding the fault-tolerant control problems for the attitude control system of the quad-rotor helicopter,proposes four different adaptive fault-tolerant control algorithms, and the main contributions of thisthesis can be summarized as follows:(1) This thesis firstly analysis the construction features and flight principles of the quad-rotorhelicopter. And then, according to the mechanical characteristics of the system, establishes thedynamics model of the attitude control system of the quad-rotor helicopter based on the Lagrangeequation. Furthermore, details the system components and model parameters of a3-DOF quad-rotorhelicopter half-physical simulation platform, which acts as the simulation object in this paper.(2) By introducing the model reference adaptive technology, this thesis presents a developeddirect adaptive compensation controller for the quad-rotor helicopter with external disturbance. Onthe basis of conventional adaptive controller, a new disturbance compensation algorithm and itsparameter adaptive law are designed. The adaptive controller given in this paper not only cancompensate the external interference, but also can make the attitude angles track the states of a givenreference system.(3) Based on the disturbance observer and switching control strategy, an adaptive fault-tolerantcontrol scheme is developed for the quad-rotor helicopter with unknown stuck actuator failures andexternal disturbance. Then, the part-disable actuator failure is also taken into account, and a directadaptive fault-tolerant algorithm is designed by introducing the system’s states feedback and theirtracking errors feedback. The proposed adaptive controller can also make the attitude angles track thestates of a given reference system, where the failure parameters and the upper bounds of the externaldisturbance are unknown.(4) Based on the above studies, the parameter uncertainty of the quad-rotor helicopter is furtherto considered. By introducing the system’s states feedback and their tracking errors feedback, animproved direct adaptive fault-tolerant controller is developed for the quad-rotor helicopter with parameter uncertainty, external disturbance and actuator failures including stuck failure andpart-disable failure. With the unknown failure parameters and upper bounds of the externaldisturbance, the proposed adaptive controller can make the attitude angles of the quad-rotor helicoptertrack a given reference output with small tracking errors.(5) Digital simulation studies are made by applying the above proposed schemes to a3-DOFquad-rotor helicopter semi-physical platform, which show the effectiveness and feasibility of thedesigned adaptive fault-tolerant controllers.