Modeling And Simulation Of The High Altitude Platform System

The high altitude platform is a kind of operation platform with certain payload hovering in the stratosphere for a long duration. The lift of the platform comes mainly from buoyancy, therefore it is capable of hovering. The operation process of the high altitude platform includes taking off and landing stages, and the hovering stage. In order to realize the-high-altitude-platform-based ground observation and ground communication, it is necessary to control the hovering and mission path tracking of the platform.The thesis focuses on the attitude control, the hovering control and the mission path tracking control of the platform. The main contents are as follows:First, based on the force analysis of the high altitude platform and some standing assumptions, the nonlinear six-degree-of-freedom mathematical model is established. Then by small perturbation method, the nonlinear model is divided into linear equations in longitudinal and lateral planes.Afterwards, using the linear models of the platform, the pitch and yaw angle controllers are established by classical control methods. Based on the attitude control system, the hovering control system is built including vertical position controller, the forward position controller and the lateral position controller. The simulation of the design is carried out using Matlab, and the result indicates the effectiveness of the designed attitude and the hovering controllers.In the final part of the thesis, the track controller of the platform is designed to realize the trajectory tracking. Due to the changes of atmospheric parameters during the rising process, , the airship pressure control system is constructed to make the internal and external pressure kept in a requited range, guaranteeing the aerodynamic shape of the platform. The simulation is conducted using Matlab, and the results show the effectiveness of the design.