Quad-Rotor Aircraft Attitude Adjustment Based On Model-Free Adaptive Control

Quad-rotor aircraft is a class of non-fixed-wing aircraft driven by four propellers with many excellent features. It can achieve a variety of unique maneuvers and has important practical applications. However, the quad-rotor aircraft is a typically complex multivariable system with strong coupling, nonlinearity and many other properties, which makes it difficult to establish mathematical model of quad-rotor aircraft and design control scheme for key indicators (such as position, attitude, etc).As a typical data-driven control algorithm, model-free adaptive control (MFAC) has favorable control performance for nonlinear system with strong coupling, time-varying and many other characteristics. Therefore, this paper will consider to introduce the data-driven control method for the quad-rotor controller design. Moreover, this article mainly focuses on the attitude control of quad-rotor aircraft, since there is coupling relationship coupling relation between the position and attitude of quad-rotor aircraft, and the attitude control directly determines the quality of position control. The thesis is organized as follows:(1) The quad-rotor aircraft dynamical model is simplified as a linear time invariant model by analyzing movement principles of quad-rotor aircraft. Then, LQR controller is designed on the basis of the model and simulation is carried out. However, the accuracy of the model is not very high, because it ignores the effects of the coordinates relative movement and friction, air and other external disturbances, resulting in that control effect of LQR controller is not ideal.(2) In order to solve the modeling issue of quad-rotor aircraft, the concept of data-driven control is introduced for the quad-rotor aircraft controller design. Firstly, a fuzzy self-tuning PID control method is introduced to avoid the tedious tuning parameters. Secondly, an improved MFAC program with order difference and second-order difference (Improved MFAC, IMFAC) is proposed for non-self-balancing systems which contain a second-order integration such as quad-rotor aircraft. Finally, MFAC-PID cascaded controller and PID controller with external loop compensation by IMFAC are designed with the combination of PID and MFAC for quad-rotor aircraft.(3) Simulations are carried out, which are implemented in Simulink platform. Through comparative analysis, controllers based on data-driven control methods, including fuzzy PID, IMFAC, MFAC-PID cascaded controller and PID controller with external loop compensation by IMFAC, have a better effect than LQR controller based on the linear time invariant model. Specifically, IMFAC and MFAC-PID integrated control schemes have smaller steady-state error and faster response speed compared with fuzzy PID controller. Moreover, MFAC-PID integrated control schemes have the strongest anti-jamming capability and work best among them.(4) Taking advantage of the quad-rotor aircraft simulator platform and MATLAB/simulink software, several real-time control experiments are implemented along with LQR, fuzzy PID and MFAC-PID cascaded controller for step signal. Then, real-time control experiments are carried out with internal disturbance and external disturbance that quad-rotor aircraft may encounter in actual. Experimental results demonstrate that MFAC-PID cascaded control scheme has superior tracking and anti-jamming capability compared with LQR and fuzzy PID controller.