Flight Control And Implementation Of Four Rotor Aircraft

A four-rotor craft has became the extensive researches in academia and industries due to its simple structure,strong maneuverability,easily operating and vertical take off/landing performances.PID control is still popular for controlling a four-rotor craft since it is not need to use a precise mathematical model of the system.Based on system errors and by adjusting the parameters of PID controller,the attitudes of four-rotor crafts can be controlled.However,it is a hard work for traditional PID control to control a four-rotor craft with highly precise performances due to the very complicated dynamics of a four-rotor craft.In this thesis,considering the difficulties of traditional PID to control a four-rotor craft,based on the corresponging research results,the main works are presented as follows:(1)Considering the flight principles of four-rotorcraft,the dynamical/kinematical equations of a four-rotor craft are established based on the Newton-Euler approach and the hybrid coordinate systems.Under the reasonable assumptions,the mathematical model of the four-rotor craft is simplified to establish the state space model,and based on the state equations,the parameter identification of the flight control system is performed.(2)Based on the nonlinear mathematical model of the four-rotor craft,the control variables are analyzed,and PID controller and back-stepping controller are designed.The attitudes and positions of the craft can be controlled by the reference signals,and the designed control algorithm s are illustrated and contrasted by MATLAB/Simulink,and according to the simulation results,it is clear that the back-stepping control algorithm can get better performances comparing with the PID control algorithm on the attitudes and positions control.(3)Based on the embedded real-time operation system uC/OS-?,the selected hardwares,and taking STM32F407 as the main microcontroller,the hardware platform for the rotorcraft is constructed.Then,the software implementation of the flight control algorithms are designed by C language,and finally,the physical simulation platform for the four-rotor craft is established.The joint debugging of hardware/software are carried out based on the constructed physical platform and the feasibility and effectiveness of the developed control algorithms are verified through the flying tests.The simulation results show that the craft can get stable within 1.1s based on the developed integral backstepping control algorithm,however,the time of the anti-integration saturation cascade PID control algorithm is 0.9s longer,and the time of the traditional PID control algorithm is 1.4s longer.Morever,there is no overshoot for integral backstepping control comparing with the anti-integration PID control and the traditional PID control.Meanwhile,under the integral backstepping control,the indoor flying tests illustrate the accuracy of is improved by 0.3~0.7 degrees,and that of the outdoor flying tests is improved by 1~3 degrees.All of these results show that the developed integral backstepping control algorithms are effective.