S. Shahmirzai Jashoghani; M. Nosratollahi
Volume 4, Issue 1 , July 2011, , Pages 49-60
Abstract
In this research optimal trajectory of lunch vehicle based on maximizing payload is being attended. At first, motion of missile concluding modeling of environment, atmosphere, gravity, mass, motion equations and aerodynamic coefficients would be simulated. Then procedure of an optimized design by using ...
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In this research optimal trajectory of lunch vehicle based on maximizing payload is being attended. At first, motion of missile concluding modeling of environment, atmosphere, gravity, mass, motion equations and aerodynamic coefficients would be simulated. Then procedure of an optimized design by using optimal control theory would be described. Applying variational calculus and mathematical modeling of optimization problems would lead project to a two point boundary condition problem which would be solved by numerical solutions such as steepest descent. At last a code would be generated in which optimal trajectory of missile calculated by using indirect optimal control and steepest descent numerical solution. An interesting point in this article is that some variables are used both as state and control variables. Hence state control variables here are divided to two groups, slow state variables concluding ones which are only state variables, and fast state variables concluding ones which are both state variables and control variables simultaneously. Solution for such control problems is described here.
S. Hossein Pourtakdost; M. Fakhri; Nima Asadian
Volume 1, Issue 1 , September 2008, , Pages 1-10
Abstract
Current practical methods of pitch programming design for multi-stage launch and ballistic vehicles suffer from several deficiencies. For many applications they are often determined for various phases of ascent trajectory utilizing simplified dynamics that results in non-optimal trajectories. Trial-and-error ...
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Current practical methods of pitch programming design for multi-stage launch and ballistic vehicles suffer from several deficiencies. For many applications they are often determined for various phases of ascent trajectory utilizing simplified dynamics that results in non-optimal trajectories. Trial-and-error design techniques coupled with flight simulation usually results in a more accurate pitch program, but that may not satisfy all the required constraints simultaneously and is also very time consuming. In this study, an integrated design environment is developed which enables a novice designer to generate optimal pitch program for the whole part of the ascent trajectory while satisfying all the required flight path constraints as well as the final time boundary conditions. Since, the preset guidance program is naturally known as an open-loop steering program, this method utilizes optimal control theory using full nonlinear system state equations together with a functional performance index to determine the optimal steering command. Evaluation of the proposed technique is demonstrated through application on a typical two stage ballistic vehicle, for which the resulting trajectory fully satisfies all the flight related and final time constraints.
