Research On The Attitude And Trajectory Tracking Control For A Hexacopter

Nowadays,the potential for multirotor UAV in civil and military applications has been well established due to its advantages such as vertical taking off and landing(VTOL),rapid maneuvering and precise hovering.This paper mainly focused on the attitude and path tracking control of hexacopter.In this paper,the development process of multirotor aircraft were firstly reviewed,as well as the research hotspots of the related technologies.The basic ideas including their advantages and disadvantages of several common control methods for multi-rotor were discussed.Then,it analyzed the dynamic characteristics of the hexacopter system,and the mathematical model of each module was obtained by reasonable simplification.Then,a set of nonlinear dynamic equations describing the motion of the hexacopter were derived based on the related dynamic knowledge.These equations were then implemented in MATLAB/Simulink,which became a good simulation platform for further studies.A double closed-loop control structure that based on the PID algorithm was designed for the studied hexacopter,which basically satisfied the position and attitude control of the aircraft.Considering the underactuated characteristic of the hexacopter,a sliding mode controller based on the underactuated system was designed,and the stability of the hexacopter was proved by the Lyapunov-based stability analysis.The simulation experiments of the PID controller and the sliding mode controller were carried out under the condition of no wind disturbance and gust interference.The results shown that the sliding mode controller based on the underactuated system has faster response time,more robustness and better control performance.Finally,considering the uncertainties such as unmodeled dynamic and unknown external disturbances of the hexacopter,a trajectory tracking controller based on ADRC algorithm was designed.Then,the simulation experiments of the PID controller and ADRC controller were carried out under the condition of slow time-varying disturbance and the change of the mass.The simulation results shown that the designed adaptive-ADRC structure has superior performance,which effectively solves the stability control problem of the hexacopter under the influence of external disturbance and internal parameter perturbation.