Research On Trajectory Control Of Lighter Than Air Vehicles Using Wind Environment

With remarkable advantages on long duration,high altitude,strong carrying capacity,high cost-effectiveness ratio and strong survivability,stratospheric light than air vehicle,which is also known as stratospheric aerostate,has great potential on applications on earth observatio n,reconnaissance and surveillance,communication relay,environmental monitoring,emergency disaster relief,scientific exploration.It has become a research hotspot in the field of aerospace and aviation.Focusing on novel stratospheric aerostat based on the use of wind field environment,this thesis systematically and thoroughly studies modeling of stratospheric wind field,design of new stratospheric aerostat,resident strategies and trajectory control methods.The main research work includes:The stratospheric wind field fast prediction models is established.Based on the proper orthogonal decomposition(POD)method,the order reduction model of the wind field is established,which is used for efficient reduction of historical wind field data.By using the periodicity and regularity of the zonal wind field,the stratospheric wind field fast prediction models based on Fourier series fitting method and BP neural network method are proposed respectively.The prediction error analysis of two wind field prediction models is completed.The conceptual design of stratospheric aerostat is completed and the sensitivity of main parameters is analyzed.According to the main technical requirements and the principle of regional residence of wind field utilization,the conceptual design of stratospheric aerostat based on wind field environment utilization is completed.The multidisciplinary analysis model is established to determine mian parameters.The design process of the overall parameters of the stratospheric aerostat based on the utilization of wind field environment is proposed.The overall parameters are designed and the sensitivity of main parameters is analyzed.The mathematical model of stratospheric aerostat is established and the trajectory simulation analysis of the stratospheric aerostat is carried out.According to the thermal environment and force situation of stratospheric aerostat,the thermodynamic model,dynamic model and altitude control model are established.Aiming at the constraints of the North-South trajectory control of the aerostat,two working modes based on the flight speed control and the North-South offset constraints are proposed.The trajectory simulation analysis of the stratospheric aerostat is carried out,and the influence of the wind field prediction model and the trajectory control strategy on the station keeping capacity of the stratospheric aerostat is discussed.The trajectory control method of the aerostat is studied and the station-keeping trajectory control is completed.By using PID control method,the flying height and North-South position controller of the aerostat are designed respectively.By controlling the aerostat,the regional residence trajectory can be effectively controlled.Aiming at the phenomenon that the PID control method has a large overshoot in the height control,a height controller based on the H? control method is designed to improve the stability and robustness of the system.The research of the thesis has important theoretical significance and engineering application value.The study on stratospheric wind field modeling and rapid prediction can provide important theoretical support for the design and application of stratospheric aerostat based on wind ultilization.The study on stratospheric aerostat trajectory control,and adopted a variety of trajectory control strategies can provide solutions for the difficulties of stratospheric aerostat residence in the region.The research on the control method of stratospheric aerostat residence trajectory can support the design and engineering implementation of stratospheric aerostat control system.