Research On Position Control Technology Of The Unmanned Helicopter In Hover And Low Speed State With Atmospheric Disturbance

Hover/low-speed flight is specific and most useful for unmanned helicopter, during which thestability of UHM is very weak. It makes the unmanned autonomous helicopter vulnerable to theeffects of atmospheric disturbance. Furthermore, it contributes to the control performance degradationand flight safety hazard. It’s necessary to improve disturbance rejection performance of the UHMduring hover and low speed flight. Position control is the core of the flight control scheme for theUHM in hover and low speed and achieves its flight functions. Therefore, this thesis researches on theproblems of position control and design disturbance rejection position control laws.First of all, To meet the needs of control law design and verification, a modeling method basedlinear models is proposed, which extracts the linear models of the typical flight state in the flightenvelope, and then connect them to reconstruct the nonlinear model. The model not only has thenonlinear characteristics of the helicopter, but also has high computational efficiency. Besides, theatmospheric disturbances model at low altitude is presented. This thesis focuses on the influence ofconstant wind and gust to helicopter trim, attitude control, position control, which laid the foundationfor the improvement of the position control law.Secondly, This thesis has compared the position control based on attitude damping in-loop withthe position control based on attitude command in-loop. The structure and control effect in the windof these normal position control law has been analyzed. Then, a improved position control based onacceleration feedback is proposed.Furthermore, aiming at the lack of wind resistance, this thesis designs position control law basedon the ADRC technology in which nonlinear PID is used in outer loop and feed-forward controller isdesigned based on extended observer. It also analyses the potential problems of application in detail.Finally, in the real time simulation environment, the designed ADRC position control law isvalidated by simulation, two flight course for landing and pirouette the ADRC control law is proved tohas higher anti-disturbance performance and higher control accuracy by two flight courses for landingand pirouette maneuver.