Mathematical Modeling Of The Stratospheric Airship And Increase Stability Control System Design

Because the airship has an ability of fixing a position for a long time in the sky, thus, the airship can provide a comprehensive service of observation and communication as a stratospheric platform. Coming into 21th century, the upsurge of research and exploitation for stratospheric airship appeared along with rapid development of correlative technology. The airship is applied for more and more transportation, observation, reconnaissance and communication. Among the many key technologies applied in development of airships, the design of auto-control system is most important, at the same time it's a challenge mission. Based on the airship's mathematics modeling, this paper has done a embedded research for the design of stability augment system. The works of study and design are as follows:1. Considering added mass, thrust vector and so on, and under certain assumptive conditions, we established 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 gained its linear state equations. Finally, we find that the state equations can be divided into longitude and lateral equation.2. Based on the nonlinear model and linear model of airship, we analyzed the airship's characteristic respectively. For the nonlinear model, we analyzed the airship's response to disturbance for the airship's stability and analyzed the airship's response to control input for the airship's manipulation in time domain. For the linear model, we analyzed the airship's performance via root locus and bode figure in the frequency domain and complex frequency domain.3. We discussed the method of Eigenstructure Assignment (EA) by the numbers and analyzed its advantage. In order to improve the airship's robust stability and decreased the sensitivity to parameter's change, EA incorporating LMI (Linear Matrix Inequities) is utilized to design the controller for the airship. We also discussed the BP network and correlative proceedings for the Neural Network.4. Appling the theory, we designed the airship's stability augment. We utilize EAbased on LMI to design the controller at selected point and utilize the training of Neural Network at unchecked point. For validating the validity of controllers, we put the controllers into natural airship's six-degree-freedom nonlinear equations to form closed loop. At last, the simulation results show the validity of airship's stability augment design.