Controller Design Of The Quad-rotor Based On ADRC

Quad-rotor is a kind of Vertical Take-Off and Landing (VTOL) multi-rotor aircraft with important military and civilian values. The flight control system of quad-rotor has characteristics of nonlinear, strong coupling and uncertainty of mathematical model and there is impact from unknown external disturbances when it works, which put forward higher requirements for the design of the quad-rotor flight control system. The Active Disturbances Rejection Controller (ADRC) does not depend on accurate mathematical model, which can develop decoupling control. This dissertation will use ADRC technology for quad-rotor flight control system to improve the limitations of traditional control methods.The main contents of this dissertation include the following aspects:Firstly, through analysis of the quad-rotor flight dynamic models and aerodynamics, dynamical model with unknown disturbances of quad-rotor with 6-DOF is derived based on Newton Euler theorem. Without considering unknown disturbances, the classic PID controller and fuzzy PID controller are designed. Simulation results show that fuzzy PID controller is better than PID controller.Secondly, through the analysis of the ADRC controller theory, ADRC controller can achieve decoupling control for the strong coupled system. Therefore, the controller for quad-rotor model with strong coupling, nonlinear, with unknown disturbance is designed based on ADRC, which can achieve hovering control without steady-state error and trajectory tracking control. Finally, simulation experiments testify the effectiveness of the controller.Thirdly, ADRC online parameter tuning for quad-rotor is achieved by introducing the fuzzy logic control. Making use of the adaptive ability of the fuzzy controller, parameter auto-tuning can be achieved. At the same time, the performance of fuzzy ADRC as well as the system robustness is improved. The controller for the quad-rotor aircraft flight control, especially the attitude angles control, has superior performance than ADRC.Finally, considering quad-rotor’s structure characteristics, this dissertation combines the concept of "time scale" with the controller parameter tuning. Through theoretical calculations and simulation analysis, the conclusions are as follows:by a simple transformation of time scale, they can be directly applied on the same order flight controller of other quad-rotor in the case of unchanged controller structure when the parameters tuning of the flight controller under a certain time scale is completed.