Design Of General-Purpose Software For Flight Vehicle Trajectory Simulation

Trajectory simulations with distinct precision should be implemented in different phases of vehicle design. In addition, the differences of simulation models exit between various types of vehicles. In order to achieve accurate result of the simulation for a certain vehicle, the designer must turn to some special programs, which just deal with particular kind of vehicle. For those researchers who deal with various vehicles, this restriction of software would cause huge waste of energies and time. It is necessary to develop quite general-purpose trajectory simulation code therefore.Aiming at the requirement, this paper is focus on designing and fulfilling the software which would be competent for trajectory numerical simulations in various circumstances: distinct vehicles;in different launch condition;uncertain phases of trajectory;with different degrees of freedom (DOF). The main efforts are made in several aspects as below:1) Guided by the object-oriented technology and the method of modular design, the frame and function modules of the software have been actualized. Several common navigation, guidance, control (NGC) models are presented as options to user. In addition, user can construct his own NGC models in two ways: the one is to gather some core modules, and the other is to replace the existing dynamic link libraries (DLL).2) The attitudes of vehicle are described by both quaternion and Euler angles, and two kinds of motion equations are established accordingly. For vehicles having different scopes of variety in attitudes, User may select proper method to simulate the 3 DOF particle translation or 6 DOF rigid airframe motion.3) Data are inputted, passed and outputted by the skill of assigning unique numbers to particular variables in the program. Hence, it becomes easy to define the interfaces of NGC module and so on.4) Some assistant codes are written in order to search and pick up the useful data in the input files. Besides, by the help of these codes, the text form interface becomes more effective and understandable. This advantage appears quite favorable especially when the parameters should be changed by the external superior programs, whichinvoke simulation software as its subroutine, such as trajectory design and optimization codes.Finally, through a few samples, the thesis validates the program in addition to presents some brief instructions. At the same time, some defects of the code and the directions of endeavor are presented.