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M.S. Thesis (Aerospace) :
" Control Oriented Analysis of Aerothermoelastic Effects for a Hypersonic Vehicle"
Committee:
PhD. Dissertation (Aerosapce) :
" Control-oriented Design to Optimize Structure for Closed-loop Performance"
Committtee:
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Sanketh BhatPhD. CandidateFlight Control Laboratory Department of Mechanical and Aerospace Engineering University of Florida sanketh@gmail.com |
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Research Project
M.S. Thesis (Aerospace) :
" Control Oriented Analysis of Aerothermoelastic Effects for a Hypersonic Vehicle"
Hypersonic
flight is seen as a feasible solution to make space travel faster,
safer and more affordable. The design of the Air-breathing hypersonic
vehicle is such that there is coupling between the structure and the
propulsion system. Therefore, the aerodynamic, propulsion and the
structural effects must be accounted to effectively model the vehicle.
The vibrations from the structure affect the performance of the
vehicle. Hence, vibration attenuation is a critical requirement for
hypersonic vehicles. The problems of vibration are compounded by
variations in heating during flight. Structural variations resulting
from the tremendous heating incurred during hypersonic fight is
mitigated by a thermal protection system (TPS); however, such
mitigation is accompanied by an increase in weight that can be
prohibitive. The actual design of a thermal protection system can be
chosen to vary the level of heating reduction, and associated weight,
across the structure.
Our study examined the design of a Linear Parameter Varying controller for an hypersonic vehicle and describes the process of control-oriented analysis to suggest a better 'Thermal Protection System' for the vehicle. A Linear Parameter Varying control architecture was used that damps any thermal effects for a range of temperature profiles. Various designs are considered for a representative model to show the large variation in flight dynamics. Simulation results indicate that the proposed methodology may constitute a feasible approach toward the development of a robust Linear Parameter Varying controller to satisfactorily address the issue of temperature effects on the dynamics of the vehicle. From the above closed-loop design analysis, important information regarding the open-loop dynamics can be obtained. We then considered how such designs and resulting thermal gradients influence the ability to achieve closed-loop performance. The resulting closed-loop performance is characterized as a function of the induced thermal gradients to indicate the optimality of the design. It is also shown that the introduction of control synthesis merely adds a linear dependency onto a nonlinear dependency which does not overly increase the computational challenge.
Our study examined the design of a Linear Parameter Varying controller for an hypersonic vehicle and describes the process of control-oriented analysis to suggest a better 'Thermal Protection System' for the vehicle. A Linear Parameter Varying control architecture was used that damps any thermal effects for a range of temperature profiles. Various designs are considered for a representative model to show the large variation in flight dynamics. Simulation results indicate that the proposed methodology may constitute a feasible approach toward the development of a robust Linear Parameter Varying controller to satisfactorily address the issue of temperature effects on the dynamics of the vehicle. From the above closed-loop design analysis, important information regarding the open-loop dynamics can be obtained. We then considered how such designs and resulting thermal gradients influence the ability to achieve closed-loop performance. The resulting closed-loop performance is characterized as a function of the induced thermal gradients to indicate the optimality of the design. It is also shown that the introduction of control synthesis merely adds a linear dependency onto a nonlinear dependency which does not overly increase the computational challenge.
Committee:
PhD. Dissertation (Aerosapce) :
" Control-oriented Design to Optimize Structure for Closed-loop Performance"
Traditionally,
the design of structural systems and vehicles has focused first on the
design of the structure and then the control and other aspects are
considered. This project suggests a simultaneous design and
optimization approach for structural systems. This integrated design
and optimization problem enlarges the design problem to include the
system-level objective, the design of the subsystems and the
interaction between the different subsystems. The integrated system
formulation motivated in this dissertation considers these aspects,
cutting across different disciplines and simultaneously optimizing the
design problem, resulting in more efficient systems. The inherent
coupling between the different subsystems increases the complexity of
the problem but reduces the design cycle time and ensures the mission
requirements are met. It is beneficial to study the coupling between
different disciplines, especially, for next-generation vehicles which
will have complex, time-varying dynamics and will need to have high
agility. This study considers the effects of aerothermoelasticity for
an air-breathing hypersonic vehicle in detail.
This dissertation considers the control-oriented design problem in depth, which focuses on the simultaneous `structural design/ controller existence' problem. The three control synthesis techniques used in this study are H2, H-infinity, and Linear Parameter Varying (LPV) theory. This study considers the design of a controller to account for the undesired effects of aerothermoelasticity in hypersonic flight as an example and describes the process of control-oriented analysis to suggest a better `Thermal Protection System' for the vehicle. The system level objective to be optimized is a closed-loop performance metric and the coupling between the different subsystems are cast as a set of feasibility constraints to the optimization problem.
This dissertation considers the control-oriented design problem in depth, which focuses on the simultaneous `structural design/ controller existence' problem. The three control synthesis techniques used in this study are H2, H-infinity, and Linear Parameter Varying (LPV) theory. This study considers the design of a controller to account for the undesired effects of aerothermoelasticity in hypersonic flight as an example and describes the process of control-oriented analysis to suggest a better `Thermal Protection System' for the vehicle. The system level objective to be optimized is a closed-loop performance metric and the coupling between the different subsystems are cast as a set of feasibility constraints to the optimization problem.
Committtee: