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Modelling, Simulation, and Control Design of an Air-breathing Hypersonic Vehicle

2005 Hypersonic planes
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Release : 2005
Genre : Hypersonic planes
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Book Synopsis Modelling, Simulation, and Control Design of an Air-breathing Hypersonic Vehicle by : Kevin P. Groves

Download or read book Modelling, Simulation, and Control Design of an Air-breathing Hypersonic Vehicle written by Kevin P. Groves. This book was released on 2005. Available in PDF, EPUB and Kindle. Book excerpt: Seen as a possible way of making space access more affordable, air-breathing hypersonic vehicles have been studied sporadically over the last five decades as the technical advances necessary for their development were missing. New technology has brought a renewed interest in the research area, as demonstrated by the successful flights of NASA's X-43A in April and November of 2004. Air-breathing hypersonic vehicles are characterized by their unique design, incorporating a supersonic combustion ramjet engine located beneath the fuselage. This esoteric configuration results in strong coupling between the thrust and pitch dynamics of the vehicle, which in combination with flexible effects and static instability make the vehicle a challenging application for control. For a particular model of the longitudinal dynamics of an air-breathing hypersonic vehicle, a nonlinear high fidelity simulation is developed. Tables are generated which provide a static mapping of the states/inputs to the aero-dynamic forces for the purpose of creating bounds to be used in future nonlinear control development. The tables also allow the calculation of the aerodynamics forces and moments to be replaced by a table look-up with multidimensional interpolation. A linear controller is designed using a linearized model derived numerically from the nonlinear simulation about a specific trim condition. The controller is designed to track given reference commands in velocity, angle-of-attack, and altitude using a LQR technique. The gains are tuned to achieve the performance objectives without violating the input constraints. The controller is then tested on the nonlinear simulation and functions adeptly. Anti-windup control is added to allow the input constraints to be considered in the formulation of the linear controller. In doing so the gains of the linear controller can be increased without manually keeping the inputs within their constraints through tuning of the weighting matrices. This allows both the speed of the closed loop response and that of the reference trajectories to be increased, resulting in better performance.

Control Oriented Modelling and Nonlinear Control Design for an Air-breathing Hypersonic Vehicle

2006 Aerodynamics, Hypersonic
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Release : 2006
Genre : Aerodynamics, Hypersonic
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Book Synopsis Control Oriented Modelling and Nonlinear Control Design for an Air-breathing Hypersonic Vehicle by : Jason Terry Parker

Download or read book Control Oriented Modelling and Nonlinear Control Design for an Air-breathing Hypersonic Vehicle written by Jason Terry Parker. This book was released on 2006. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This thesis describes control oriented modelling, i.e. the development of a model which is amenable to control design, of an air-breathing hypersonic vehicle and nonlinear control design based on the constructed model. The full simulation model, or truth model, includes intricate couplings between the engine dynamics and the flight dynamics, along with complex interplay between the flexible and rigid modes of the vehicle. Furthermore, this model is found to be unstable and non-minimum phase with respect to the variables to be controlled. By replacing the complex force and moment functions with curve fitted approximations, neglecting certain weaker couplings, resorting to dynamic extension at the input side, and neglecting slower portions of the system dynamics, a control oriented model with full vector relative degree with respect to the regulated output is obtained. Standard dynamic inversion can then be applied to this model, resulting in approximate linearization of the input/output map of the truth model. A robust outer loop control is then designed using LQR with integral augmentation in a model reference scheme. Simulation results demonstrate that this technique achieves excellent tracking performance even in the presence of small plant parameter variations. The fidelity of the truth model is then increased by including additional flexible effects which render the original control design ineffective. A more elaborate control approach with an additional actuator is then employed to compensate for these new flexible effects, and simulation results which include mild plant parameter variations are presented.

Control-oriented Modeling and Output Feedback Control of Hypersonic Air-breathing Vehicles

2008 Hypersonic planes
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Release : 2008
Genre : Hypersonic planes
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Book Synopsis Control-oriented Modeling and Output Feedback Control of Hypersonic Air-breathing Vehicles by : David Orn Sigthorsson

Download or read book Control-oriented Modeling and Output Feedback Control of Hypersonic Air-breathing Vehicles written by David Orn Sigthorsson. This book was released on 2008. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Hypersonic air-breathing vehicles are a promising and cost-efficient technology for launching low-earth-orbit satellites and providing rapid global-response capabilities. Modeling and control of such vehicles has been an active subject of research in recent years. A first-principle, physics-based model (FPM) of the vehicle's longitudinal dynamics has been developed at the Air Force Research Laboratory, and made available to the academic community for control systems design. This model, while suitable for simulation, is intractable for model-based control, thus requiring further control-oriented modeling. A typical control objective is to track a velocity and altitude reference while maintaining physical feasibility of the control input and the state. Two control strategies are presented in this work. The first is a linear time invariant (LTI) design based on a novel formulation of a robust servo-mechanism using singular perturbation arguments. This approach does not rely on state reconstruction but does require an analysis of a family of linearized models from the FPM. The second design relies on reduced-complexity modeling of the FPM. Intractable expressions of the forces and moment in the FPM are replaced with a curve-fit model (CFM). The CFM is expressed as a linear parameter varying (LPV) system, where the scheduling variables depend on the system output. A novel LPV regulator design methodology is developed, which explicitly addresses the case of over-actuated models (i.e., models with more inputs than performance outputs). This is a non-trivial extension of the analysis and design of output regulators for LTI systems. The LPV regulator separates the control problem into a steady-state controller and a stabilizing controller. The steady-state controller produces a non-unique approximate steady-state using receding horizon constrained optimization, while the stabilizer renders the steady-state attractive. The steady-state controller represents an approach to addressing over-actuated LPV systems, alternative to static or dynamic control allocation, or standard optimal control. The stabilizer design utilizes the LPV separation principle to decompose the problem into state feedback and LPV reduced order observer design. Both approaches are applied to the FPM in simulation and their merits and drawbacks discussed.

Reference Command Tracking for a Linearized Model of an Air-Breathing Hypersonic Vehicle

2005
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Release : 2005
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Book Synopsis Reference Command Tracking for a Linearized Model of an Air-Breathing Hypersonic Vehicle by :

Download or read book Reference Command Tracking for a Linearized Model of an Air-Breathing Hypersonic Vehicle written by . This book was released on 2005. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this paper is on control design and simulation for an air-breathing hypersonic vehicle. The challenges for control design in this class of vehicles lie in the inherent coupling between the propulsion system, and the airframe dynamics, and the presence of strong flexibility effects. Working from a highly nonlinear, dynamically-coupled simulation model, control designs are presented for velocity, angle-of-attack, and altitude command input tracking for a linearized version of a generic air-breathing hypersonic vehicle model linearized about a specific trim condition. Control inputs for this study include elevator deflection, total temperature change across the combustor, and the diffuser area ratio. Two control design methods are presented, both using linear quadratic techniques with integral augmentation, and are implemented in tracking control studies. The first approach focuses on set point tracking control, whereas in the second, a regulator design approach is taken. The effectiveness of each control design is demonstrated in simulation on the full nonlinear model of the generic vehicle.

Geometry Modeling and Adaptive Control of Air-breathing Hypersonic Vehicles

2014
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Release : 2014
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Book Synopsis Geometry Modeling and Adaptive Control of Air-breathing Hypersonic Vehicles by : Tyler J. Vick

Download or read book Geometry Modeling and Adaptive Control of Air-breathing Hypersonic Vehicles written by Tyler J. Vick. This book was released on 2014. Available in PDF, EPUB and Kindle. Book excerpt: Air-breathing hypersonic vehicles have the potential to provide global reach and affordable access to space. Recent technological advancements have made scramjet-powered flight achievable, as evidenced by the successes of the X-43A and X-51A flight test programs over the last decade. Air-breathing hypersonic vehicles present unique modeling and control challenges in large part due to the fact that scramjet propulsion systems are highly integrated into the airframe, resulting in strongly coupled and often unstable dynamics. Additionally, the extreme flight conditions and inability to test fully integrated vehicle systems larger than X-51 before flight leads to inherent uncertainty in hypersonic flight. This thesis presents a means to design vehicle geometries, simulate vehicle dynamics, and develop and analyze control systems for hypersonic vehicles. First, a software tool for generating three-dimensional watertight vehicle surface meshes from simple design parameters is developed. These surface meshes are compatible with existing vehicle analysis tools, with which databases of aerodynamic and propulsive forces and moments can be constructed. A six-degree-of-freedom nonlinear dynamics simulation model which incorporates this data is presented. Inner-loop longitudinal and lateral control systems are designed and analyzed utilizing the simulation model. The first is an output feedback proportional-integral linear controller designed using linear quadratic regulator techniques. The second is a model reference adaptive controller (MRAC) which augments this baseline linear controller with an adaptive element. The performance and robustness of each controller are analyzed through simulated time responses to angle-of-attack and bank angle commands, while various uncertainties are introduced. The MRAC architecture enables the controller to adapt in a nonlinear fashion to deviations from the desired response, allowing for improved tracking performance, stability, and robustness.

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