TY - GEN

T1 - Using sensitivity penalties to robustify the optimal reentry trajectory of a hypersonic vehicle

AU - Akman, Tugba

AU - Diepolder, Johannes

AU - Grüter, Benedikt

AU - Holzapfel, Florian

N1 - Publisher Copyright:
© 31st Congress of the International Council of the Aeronautical Sciences, ICAS 2018. All rights reserved.

PY - 2018

Y1 - 2018

N2 - In the paper at hand, an optimal reentry trajectory for a winged hypersonic vehicle is calculated, where the maximum heat flux at the stagnation point is minimized. The main contribution of this paper is the robustification of the optimal reentry trajectory against air density fluctuations resulting in a robust trajectory, where the heat flux over the flight time is less sensitive against perturbations in air density. For this purpose, sensitivities describing the rate of change of the heat flux with respect to perturbations in air density are minimized. Solving the associated optimal control problem is based on direct solution methods, where the problem is discretized and solved as a finite dimensional optimization problem. The robustness is achieved by a two-step optimization. In the first optimization, the nominal problem, where the maximum heat flux is minimized, is to be solved. In the second optimization, high sensitivities are penalized by formulating a new cost function consisting of the sum of the maximum heat flux and weighted sensitivities resulting in robust optimal controls.

AB - In the paper at hand, an optimal reentry trajectory for a winged hypersonic vehicle is calculated, where the maximum heat flux at the stagnation point is minimized. The main contribution of this paper is the robustification of the optimal reentry trajectory against air density fluctuations resulting in a robust trajectory, where the heat flux over the flight time is less sensitive against perturbations in air density. For this purpose, sensitivities describing the rate of change of the heat flux with respect to perturbations in air density are minimized. Solving the associated optimal control problem is based on direct solution methods, where the problem is discretized and solved as a finite dimensional optimization problem. The robustness is achieved by a two-step optimization. In the first optimization, the nominal problem, where the maximum heat flux is minimized, is to be solved. In the second optimization, high sensitivities are penalized by formulating a new cost function consisting of the sum of the maximum heat flux and weighted sensitivities resulting in robust optimal controls.

KW - Aerothermodynamics

KW - Reentry

KW - Robust Optimal Control

KW - Sensitivity Penalty

KW - Trajectory Optimization

UR - http://www.scopus.com/inward/record.url?scp=85060475259&partnerID=8YFLogxK

M3 - Conference contribution

AN - SCOPUS:85060475259

T3 - 31st Congress of the International Council of the Aeronautical Sciences, ICAS 2018

BT - 31st Congress of the International Council of the Aeronautical Sciences, ICAS 2018

PB - International Council of the Aeronautical Sciences

T2 - 31st Congress of the International Council of the Aeronautical Sciences, ICAS 2018

Y2 - 9 September 2018 through 14 September 2018

ER -