Research On Fixed Point Hovering Guidance Method For Stratospheric Airship

Stratospheric airship is an ideal aerostat application platform,which has broad prospects in the fields of ground monitoring,disaster forecast and communication relay.Stratospheric airships can carry long-term project with heavy loads,hover for a long time in fixed positions and have unique capabilities to gaze the ground.Estimation of stratospheric airship's own state parameters and wind field and designing proper hovering guidance law are the keys to achieve stratospheric airship's hovering.Based on the accurate estimation of the wind field and the parameters of the airship,the dissertation designs the rough guidance and the precise guidance of the airship using the fuzzy PID control method,and verifies the guidance effect of the method.First of all,a six-degree-of-freedom nonlinear model of airship is established based on flight mechanics.Secondly,a new method which is based on data from different measurements,decoupling analysis and use of unscented Kalman filter is proposed to estimate the environmental wind field and the parameters of the airship.Based on the data obtained from the flight test,the method is validated.Afterwards,the hovering guidance process is divided into two steps of rough guidance and precise guidance,which both have a clear guidance target for each stage.At last,fuzzy PID control method is used to design and simulate the generalized proportional guidance law and angle of attack,as well as the speed and the angle of slide in the precise guidance phase respectively.The results show that the proposed method can estimate the related data in real time.The generalized proportional guidance law is effective in guiding the airship.The fuzzy PID control method has good effect on the airship's angle of attack,angle of slide and speed which meets the need of hovering guidance.The research of the dissertation provides a reference for the hovering guidance of the airship.