Research On Automatic Takeoff And Landing Control Technology For Unmanned Helicopter

Automatic takeoff and landing is one of the most important function of unmanned helicopter, which is the key phase for mission completion. The basic flight requirement has been fulfilled by using primary control strategy. However, the control performance can not meet the engineering requirements in the complex environment.This thesis aims at several desiderating problems and presents advanced control strategy.Firstly, this paper analyzes the aerodynaminc characteristics of unmanned helicopter in detail, which is to clarify the main factor influencing the performance of takeoff and landing that is the external environment not the dynamics characteristic of hover state. It lays the foundation for the control law designing. This thesis analysis the performance of the conventional control method and illustrates the insufficient control performance, the improved height control scheme based on the rate of height is put forward, and reveal the nature of the improved control method. The improved scheme obtains higher control accuracy and better robustness under the typical disturbance uncertainty factors, which makes up the shortcomings of the conventional one.Secondly, according to the power criterion and the vortex ring theory, the rate of height is designed, which is based on the practice project of unmanned helicopter. The improved control law of height channel is applied to the automatic takeoff and landing phase. Besides, the full automatic takeoff and landing control strategy is establishment according to the position and heading scheme of hover state. In order to avoid the influence of sensor dead zone, two different kinds of landing methods are proposed by analysing their feasibility.Finally, in order to verify the performance of control law rapidly, an equivalent simulation environment is developed, which is based on the six degrees of freedom nonlinear model of RotorLib. What’s more, aiming at the particularity of takeoff and landing, some typical simulation cases are designed, and the result of simulation indicates that the control law has better control effect and adaptability, which enhances the quality of flight control meeting the requirements of engineering application.