Research On Control Of Quadrotor Based On PID And Integral Sliding Mode

Quadrotor is a kind of multi-rotor aircraft that can take-off and land vertically and hover at a fixed point.Compared with other aircraft,quadrotor has broad application prospect and research value in the field of military and civilian due to the advantages of small volume,simple mechanical structure,light weight,strong flexibility and so on.Since the quadrotor is known as a under-actuated,multi-variable,strong coupled,nonlinear system,and it is sensitive to disturbance,there are some difficulties in the design of the controller.In this paper,the quadrotor is regarded as the rsearch object,a series of research work is carried out to meet the target of designing a robust flight controller.First of all,the ground coordinate system and the body coordinate system are defined and the conversion relation between them is derived on the basis of the detailed analysis of the structure and flight principle of the quadrotor.After selecting the key forces and torques,the six-DOF(Degree of Freedom)nonlinear system model of quadrotor is established according to the Newton' laws and momentum theorem.Then,a double-loop controller is proposed based on the nonlinear system model of quadrotor.A classical PID control method is chosen to control the outer-loop subsystem due to its simple structure and strong robustness.The conventional integral sliding mode control method can eliminate the steady state error in the presence of perturbation,but it is easy to produce integral windup and lead to large overshot,therefore an improved integral sliding mode control method is designed to control the inner-loop subsystem.Simulation results show that the proposed controller can realize the quadrotor hoving and trajectory tracking.Finally,a double-loop control system based on fuzzy PID and improved integral sliding mode is proposed to deal with the classical PID control can not adjust the PID parameters according to the change of system.A fuzzy PID controller is applied in the outer-loop subsystem while an improved integral sliding mode control method is designed in the inner-loop subsystem.The Simulation results show that fuzzy PID controller has a significant improvement in the response speed compared with classical PID controller and can realize the online self-tuning of PID parameters.