Trajectory Optimization Design Of Stratospheric Airships

The stratospheric airship, used as an operation platform at the height of thestratosphere, is capable of hovering in fixed location for a long duration with certainpayload. As a high altitude platform, the fight mission of a stratospheric airshipconsists of taking-off, landing, position-keeping, cruising, etc. Compared with therelative stability of atmospheric environment in the troposphere, the atmosphericenvironment in the stratosphere, through which the airship has to fly in taking-off orlanding, is rather disarrayed. As a result, the optimal trajectory control of taking-offor landing for the stratospheric airship is of great theoretical importance, as well asurgency in practical applications.Since there exists a great similarity between the taking-off and landing of thestratospheric airship, the research in the thesis focuses on the trajectory optimizationdesign in the taking-off of the airship. Main research consists of the following.First, the system buildup of the stratospheric airship is introduced. Under certainassumptions, forces analysis is conducted for the airship, based on which thenonlinear six degree-of-freedom mathematical model is constructed.Then, the technological demands for the operation management of thestratospheric airship, and the technological schemes for operation managementsystem are given. Based on the operation management system, the implementationscheme of the optimal trajectory control is proposed. Based on the proposed scheme,the design problem of trajectory optimization is mathematically formulated as anoptimal control problem, and, furthermore, transformed to a parameter optimizationproblem.In the final part of the thesis, a solving procedure based on hybrid geneticalgorithm is proposed for the given parameter optimization problem. The trajectoryoptimization design problem of the airship’s taking-off is solved following theproposed solving procedure, and simulation validation is conducted for differentcases.