Research on Trajectory Optimization Based on Simultaneous Method in Launch Vehicles Ascent Stage
Aiming at the trajectory optimization problem of the ascending stage of launch vehicle in the atmosphere with complex and multi constraints,a trajectory optimization method based on simultaneous method is proposed.The method adopts the direct method under the simultaneous framework,discretizes the state variables and control variables through the finite element orthogonal collocation method,and then solves the discrete nonlinear programming problem by the interior point method,so as to balance the calculation efficiency and solution accuracy,and improve the autonomy and task adaptability of trajectory optimization.Aiming at the problem that the larger the scale of the discrete nonlinear programming problem is,the more time-consuming the gradient matrix calculation is,making full use of the sparsity of the partial derivative matrix,the solution of the non-zero term in the NLP gradient is transformed into the solution of the partial derivative of the original optimal control problem,so as to further improve the efficiency of trajectory optimization.The simulation results show that this method can complete the flight mission well and meet constraints.
simultaneous framefinite element orthogonal collocation methodinterior point methodgradient matrixsparsity
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