Research On Control Technology Of Unmanned Aerial Vehicle Based On Disturbance Rejection

Quadrotor UAV, which has the ability of vertically taking off and landing, is a vehicle with simple structure and of reliable performance. It has advantages such as hovering, flying with low speed and flexibility of operation which fixed-wing aerial vehicles don’t have. Comparing with a traditional helicopter, it has characteristics of easy operation, low manufacturing requirements and good stability. In recent years, because of the advantages and the applications in unmanned inspection, important events security and traffic supervision, Quadrotor UAV has become a hot research issue in control field. Due to the dimensions of control input is less than the degrees of freedom of the system, the underactuated characteristic is the difficulty of obtaining the desired performance, on the other hand, the characteristic of multi-variable, nolinear and the uncertainty of the system has also brought challenges to the control strategy. In most practical control system, external disturance and system uncertanty is the key problems that influence system performance, Quadrotor UAV is no exception.So, the paper mainly discuss the control problem of Quadrotor UAV with the consideration of external disturance and system uncertanty,we de-sign the controller of attitude control and trajectory tracking control respectively. Simulations and experiments are carried out to validate the proposed control method. The main work and contributions are as follows:1.The attitude control of the Quadrotor UAV. Concerning the modeling of the nolinear attitude sub-system, traditional model of Quadrotor UAV uses the Euler angles to describe the attitude dynamics of the aircraft. However, the Euler angle method involve solving transcend functions and has a singularity problem, which make the design of the controller a difficulty. For this problem, based on the attitude dynamics of the servo system, the nonlinear error model is established by the quaternion. Then, a nonlinear generalized predictive controller of the error model is designed, the NDOB is used to estimate system uncertainty and disturbance to guarantee the disturbance rejection performance.2. The trajectory tracking control of the Quadrotor UAV. For the control of position sub-system depends on the output of attitude sub-system, this part still use quaternion to describe the attitude. Based on the kinematics model of the aircraft, we establishe position sub-system model. With the consideration of external disturbance, based on the backstepping strategy, we design the trajectory tracking controller, at the same time, a ESO is desigend to estimate the disturbance and compensate the control input to improve the control accuracy.3. Experiments and simulations of the control method of the Quadrotor UAV. Firstly a Quadrotor UAV platform is established, then the validity of the attitude control method is verified through experiments and simulations, also the affectivity of the trajectory tracking control strategy is tested through simulations.