The Robust Adaptive Control Of Quad-Rotor Aircraft

In recent years, with the development of science and technology, the quad-rotor aircraft is increasingly being applied to military and civilian aspects because of its many merits such as simple structure, low cost, and completing the vertical take-off, fixed point hover, low altitude and super low speed flight and so on. However, the quad-rotor system is a typical nonlinear, multivariable and highly coupled underactuated system, and it is vulnerable to many interference factors during flight, so it is difficult to build its accurate dynamic model and to design flight control algorithms. Although many kinds of control algorithms have been designed to quad-rotor aircraft control, the results show that the actual control effects still remain to be improved. Therefore, we need to study effective control strategies to obtain satisfactory flight control.This thesis mainly studies the nonlinear control methods of micro quad-rotor according to the characteristics of its own model on the basis of the overviews about the application status, key technology, application prospects and control methods of the micro quad-rotor aircraft. We design two nonlinear control algorithms and the main research contents and results are as follows.First of all, the thesis builds parametric uncertainty disturbed nonlinear mathematical model of quad-rotor through stress analysis, the model not only takes into account parametric uncertainty within the system, but also takes into account external interference. Therefore, the model is more accurate and it has more practical significance.Secondly, a full control algorithm based on robust adaptive control is designed. For uncertain parameters of the internal systems, adaptive laws are designed to estimate them online and a robust function is designed to inhibit its effects with respect to external disturbance part. Further more, the thesis uses the smooth projection method to prevent system instability, parameter drift and other issues. The final simulation results demonstrate the effectiveness of the design algorithm.Thirdly, we design an attitude control algorithm of quad-rotor aircraft based on adaptive internal model principle. We firstly establish a nonlinear model whose external disturbance is completely unknown and then we design an attitude control algorithms using the internal model theory. The robustness of the method and satisfactory tracking perfermance is proved through theoretical analysis. Finally, the simulation shows the effectiveness of the proposed algorithm.A comprehensive nonlinear mathematical model of quad-rotor aircraft is established and we design two nonlinear control algorithms according to its properties. The effectiveness of the algorithms are proved through theoretical analysis and simulation results. This thesis will provide some theoretical basis for the further research of the quad-rotor aircraft.Finally, the thesis makes a summary of the research and points out some open problems to be explored in future.