Research On Modeling And Control Of The Stratospheric Airship Platform

The stratospheric airship platforms have an ability of fixing a position for a long time in the sky, so airships can provide a comprehensive service of observation and communication. The upsurge of research and exploitation for stratospheric airship appeared along with rapid development of correlative technology. Among the many key technologies applied in the development of airships, the design of attitude control system is most important, at the same time it's a challenge mission because of its unusual complexity. Based on the stratospheric airship platforms, this paper presents the airship's mathematics modeling and has done a embedded research for the design of attitude control system. The works of study and design are as follows:1. Develop the airship's mathematics modeling. Considering added mass, aerodynamics and so on, and under certain assumptive conditions, we developed a six-degree-freedom nonlinear equations of stratospheric airship in this paper. In order to investigating airship's contact between the figure parameter and airship's characteristic, we linearized its six-degree-freedom nonlinear equations and got the linear equations. Finally we find that the state equations can be divided into longitude and lateral equations.2. Based on the nonlinear model and linear model of airship, we analyzed the airship characteristic and simulated them. By means of validating the correct of the model, we presented the airship's model by using Matlab&Simulink, and simulated the control inputs and motion disturbances. Based on the study of the transient performance, we studied the latent root distributing of longitude and lateral systems. A conclusion is made that the motion of airship is unstable based on the eigenvalue analysis.3. This thesis designs the stratospheric airship platforms' attitude control systems and simulates the modeling system. Based on the knowledge of attitude control, designed the attitude control theory of the airship which includes attitude and altitude control system. The attitude control is divided into pitch and yaw attitude control. The inputs of them are the elevator and rudder respectively. Control laws are designed for them using classical PID control and variable structure control(VSC).These control laws both gets good results of controlling the attitude of airship. But, from the simulation results, we can get that the VSS control is better than the classical PID control because of its robustness and adaptiveness.