Ponencias (Ingeniería Aeroespacial y Mecánica de Fluidos)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11334

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Mostrando 1 - 20 de 79

A Probabilistic Storm Avoidance Concept for En-Route Flight
(2020-12) Franco Espín, Antonio; Valenzuela Romero, Alfonso; Rivas Rivas, Damián; Sacher, Daniel; Lang, Jürgen; Hauf, Thomas; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; European Union (UE). H2020; Universidad de Sevilla. TEP945: Ingeniería Aeroespacial
In this paper a probabilistic weather avoidance concept is presented, which integrates new meteorological capabilities in the storm avoidance process, namely, probabilistic nowcasts. These new meteorological products provide not only a forecast of the storm evolution, but also information about the uncertainty of the convective cells. In this concept, the required input is a probabilistic nowcast and a risk level, which is an adjustable parameter intended to define the avoidance strategy. The output is a unique avoidance trajectory that takes into account the uncertainty of the convective cells, obtained for the given risk level. Simulation results show that the safety and the workload of pilots and air traffic controllers are improved, although with a small loss of flight efficiency, compared to today’s practice. This new weather avoidance concept will be used in a follow-up project, with the goal of developing a Medium-Term Storm Avoidance tool intended to enhance air traffic control efficiency.
Use of Convective Indices to Improve the Prediction of Departure Delays
(SESAR Innovation Days, 2023-11) Núñez Portillo, Juan Manuel; Valenzuela Romero, Alfonso; Franco Espín, Antonio; Rivas Rivas, Damián; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP945: Ingeniería Aeroespacial
Severe convective weather disrupts European aviation, causing flight deviations and delays. This study addresses the challenge of improving long-term flight predictability, beyond two hours, focussing on departure delays. It explores the potential of convective indices, derived from atmospheric data, as proxies for departure delays. Despite limitations, these indices are appealing due to their simplicity and widespread availability in medium-range weather forecasts. The research collects historical flight data from Europe and correlates departure delays with convective indices. Deterministic and probabilistic prediction models are developed, evaluating their performance against baseline flight plan predictions. The results reveal that using convective indices significantly enhances the prediction of departure delay, particularly in probabilistic models. Lifted, Boyden, and Bradbury indices show promise. Future work includes multi-index predictors, airport-specific indices, machine learning techniques, and the extension of this approach to other flight deviations.
Experiences and Insights from a Mini-Course on Responsible Generative AI Use in Aerospace Engineering
(Elsevier, 2024-07-01) Vázquez Valenzuela, Rafael; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Universidad de Sevilla. TEP945: Ingeniería Aeroespacial
This paper presents the experiences and insights gained from a small-scale implementation of a mini-course on responsible generative AI use in aerospace engineering education. The course, conducted as a 2-hour voluntary lab session at the University of Sevilla, aimed to introduce final-year undergraduate students to AI tools and techniques, focusing on applications such as text generation, code assistance, and data visualization. The course design emphasized hands-on experience, interactive discussions, and the importance of responsible and ethical AI use. Student projects and feedback are analyzed, highlighting the potential and limitations of AI tools in enhancing skills. The paper concludes with implications for aerospace engineering education.
A Symmetry-Based Unscented Particle Filter for State Estimation of a Ballistic Vehicle
(Elsevier, 2023) Rebollo Fernández, José Antonio; Vázquez Valenzuela, Rafael; Gavilán Jiménez, Francisco; Cordero, Jorge; Jiménez, Javier; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP-945: Ingeniería aeroespacial
The problem of state estimation for vehicles when an initial fix is highly uncertain and/or the number of sensors is not sufficient (and changes with time) is very relevant for both aircraft and spacecraft navigation. This work proposes a Locally Linearized Particle Filter based on a quaternion-adapted Unscented Kalman Filter to estimate the state of a vehicle with minimal sensors and uncertain initial conditions, exploiting geometrical symmetries. The algorithm is applied to a ballistic vehicle navigating towards a laser-illuminated target using on-board sensors, including a triad of accelerometers and gyroscopes, a barometric altimeter and a laser receiver. A symmetry around the vertical axis is identified; based on it, the algorithm becomes capable of solving the navigation problem, even with highly uncertain initial conditions and without enough sensor information; this second condition is particularly severe when the laser receiver is not yet obtaining data. The proposed navigation algorithm offers promising results in simulation, rapidly converging to an accurate estimate of the real trajectory when the laser receiver becomes active.
Preliminary study of the impact of using hydrogen with a fuel cell for aircraft propulsion in an existing platform
(2022) Frutos, Víctor M. de; Parra Vilar, Juan Ramón; Bordons Alba, Carlos; Esteban Roncero, Sergio; Universidad de Sevilla. Departamento de Ingeniería de Sistemas y Automática; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; Universidad de Sevilla. TEP945: Ingeniería Aeroespacial
In the pursue of truly achieving the decarbonisation of air transport, several initiatives have been launched within the aeronautical industry with very different approaches. Despite that many studies have been conducted over the last years, including trials with demonstration flights for fuel cell-based aircraft platforms or for burning hydrogen propulsion, these studies have never gone beyond prototype status. One of the most promising presented alternatives is the incorporation of hydrogen technology in the power plant of flying platforms in order to reduce the carbon footprint. Two ways are contemplated for the introduction of hydrogen technology in the power plant of an aircraft: the burning of hydrogen in a combustion engine and the use of a fuel cell to generate energy to fly. Prior to consider the hydrogen utilization as an alternative, it is necessary to evaluate the impact that such technology might have in aircrafts utilization. The greener option for hydrogen utilization is using a fuel cell as the outcome of the energy production is only water. It is considered in this paper that this impact could be evaluated in the analysis and comparison of the PL (Pay Load) vs. R (range) diagram between two platforms: a traditional platform with engines as Power Plant and a modified platform from that original one using fuel cells and electrical motors as power plant. This article presents a comparison analysis between both platforms by presenting a methodology using preliminary study focused on the cruise phase as it is the more relevant phase to evaluate the range of the aircraft. The direct application of this methodology to a case study will give to the reader the level of the impact of the new technology introduction. Then the optimization in a computational code of this methodology will permit to perform sensitivity studies and to establish metrics and objectives to reduce the impact in the aircraft utilization because of this new technology.
Backstepping control of a hyperbolic PDE system with zero characteristic speed
(Elsevier, 2022) Andrade, Gustavo A. de; Vázquez Valenzuela, Rafael; Karafyllis, Lasson; Krstic, Miroslav; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Universidad de Sevilla; Agencia Estatal de Investigación. España; Universidad de Sevilla. TEP945: Ingeniería Aeroespacial
In this paper, we study the single-input boundary feedback stabilization of 3 × 3 linear hyperbolic partial differential equations (PDEs) with two counterconvecting PDEs and the third one with zero characteristic speed. We design a full-state backstepping controller which exponentially stabilizes the origin in the L2sense. The zero transport velocity makes the previous backstepping designs inapplicable (their application would result in a controller with infinite gains). To employ backstepping in the presence of zero speed, we use an invertible Volterra transformation only for the PDEs with nonzero speeds, leaving the state of the zero-speed PDE unaltered in the target system, but making the target zero-speed PDE input-to-state stable with respect to the decoupled and stable counterconvecting nonzero-speed PDEs. In addition to achieving stabilization, we produce an explicit bound on the rate of convergence of the target system by a method of successive approximations and the use of Laplace transform. Simulation results are presented to illustrate the effectiveness of the proposed control design.
Output feedback control of radially-dependent reaction-diffusion PDEs on balls of arbitrary dimensions
(Elsevier, 2020) Vázquez Valenzuela, Rafael; Zhang, Jing; Krstic, Miroslav; Qi, Jie; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Fundación Nacional de Ciencias Naturales de China (NSFC); Universidad de Donghua; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Universidad de Sevilla. TEP945: Ingeniería Aeroespacial
Recently, the problem of boundary stabilization and estimation for unstable linear constant-coefficient reaction-diffusion equation on n-balls (in particular, disks and spheres) has been solved by means of the backstepping method. However, the extension of this result to spatially-varying coefficients is far from trivial. Some early success has been achieved under simplifying conditions, such as radially-varying reaction coefficients under revolution symmetry, on a disk or a sphere. These particular cases notwithstanding, the problem remains open. The main issue is that the equations become singular in the radius; when applying the backstepping method, the same type of singularity appears in the kernel equations. Traditionally, well-posedness of these equations has been proved by transforming them into integral equations and then applying the method of successive approximations. In this case, with the resulting integral equation becoming singular, successive approximations do not easily apply. This paper takes a different route and directly addresses the kernel equations via a power series approach, finding in the process the required conditions for the radially-varying coefficients and stating the existence of the series solution. This approach provides a direct numerical method that can be readily applied, despite singularities, to both control and observer boundary design problems.
A Backstepping-based observer for estimation of thermoacoustic oscillations in a Rijke tube with in-domain measurements
(Elsevier, 2020) Andrade, Gustavo A. de; Vázquez Valenzuela, Rafael; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Universidad de Sevilla. TEP945: Ingeniería Aeroespacial
This paper presents an observer design for estimation of thermoacoustic instabilities in a Rijke tube. To study this problem, we consider that the acoustic dynamics is represented by the wave equation with a point source term representing the heat release. In turn, the heat release dynamics is given by a first-order ordinary differential equation (ODEs). The observer, whose design is based on the backstepping methodology, relies on measurements of acoustic pressure and velocity at an arbitrary point of the domain. The design employs a folding transformation (with two folds) around the measurements and the heat release point, allowing to write the system into a form with more states but boundary measurements and ODE couplings. Then, we formulate a well-posed and invertible integral transformation with both triangular and full terms that maps the observer error dynamics into an exponentially stable target system. The theoretical results were tested through numerical simulations in order to show the effectiveness of the design.
Backstepping-Based Exponential Stabilization of Timoshenko Beam with Prescribed Decay Rate
(Elsevier, 2022) Chen, Guangwei; Vázquez Valenzuela, Rafael; Krstic, Miroslav; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; Universidad de Sevilla. TEP945: Ingeniería Aeroespacial
In this paper, we present a rapid boundary stabilization of a Timoshenko beam with anti-damping and anti-stiffness at the uncontrolled boundary, by using PDE backstepping. We introduce a transformation to map the Timoshenko beam states into a (2+2) × (2+2) hyperbolic PIDE-ODE system. Then backstepping is applied to obtain a control law guaranteeing closed-loop stability of the origin in the H1 sense. Arbitrarily rapid stabilization can be achieved by adjusting control parameters. Finally, a numerical simulation shows that the proposed controller can rapidly stabilize the Timoshenko beam. This result extends a previous work which considered a slender Timoshenko beam with Kelvin-Voigt damping, allowing destabilizing boundary conditions at the uncontrolled boundary and attaining an arbitrarily rapid convergence rate.
Implementation in MATLAB of a Multiplicative Extended Kalman Filter for live estimation of a smart device's attitude
(Elsevier B.V., 2021) Utrera, Javier; Vázquez Valenzuela, Rafael; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Ministerio de Ciencia e Innovación (MICIN). España
This work introduces the tools used to teach the Kalman Filter (KF) to Aerospace Engineering students in the University of Seville. In particular, an easy-to-set-up application is introduced; based on the Matlab framework on its 2020b (or newer versions), it is able to display the attitude of a smart device in real time through a wireless connection to a computer. This tool is a simple yet powerful educative resource when teaching about the KF, since it showcases its performance while allowing the student to understand how a complex real-world problem can be solved using a relatively simple implementation of the KF; in particular, the Multiplicative Extended KF (MEKF) is chosen, but the framework can be easily adapted to other versions such as the Extended or Unscented KF. In addition, the tool allows the student to be aware of the inner workings of the filter itself, learning about its advantages and limitations compared with other attitude estimation algorithms. The student is also able to understand how the filter needs to be tuned, and to observe the results of the experiments in a visual and straightforward manner.
Buenas prácticas paisajísticas en la modernización agraria
(Universidad de Extremadura, Servicio de Publicaciones, 2010) Prada LLorente, Esther Isabel; Riesco Chueca, Pascual; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos
En los paisajes rurales conviven elementos materiales e inmateriales cuyo engranaje es accionado por procesos socio-económicos de alcance global. Los valores paisajísticos del medio rural son un ingrediente fundamental en la calidad de vida, y no sólo para quienes residen en el campo, sino también para la población urbana, cuyo asueto y vida laboral dependen de forma creciente de recorridos y estancias en espacios de dominante rural. Es prioritario encontrar inspiración para modelar el futuro paisajístico de estos espacios, y reforzar sus potenciales aportaciones a la sociedad: (1) calidad de vida para residentes y viajeros; (2) excelencia productiva para las iniciativas en el medio rural. Reconocer los valores de estos paisajes, comprender su enraizamiento antropológico, mostrar la vulnerabilidad de su carácter ante cambios estructurales, materiales y otros fenómenos de naturaleza larvada, y sugerir medidas prácticas para orientar la evolución futura de tales espacios: éstas son las tareas que se esbozan aquí, ilustradas con el ejemplo de una próxima intervención paisajística en la comarca de Sayago (Zamora)
The natural breakup length of a steady capillary jet
(Bulletin of the American Physical Society, 2019) Gañán-Calvo, Alfonso M.; Chapman, H. N.; Heyman, Michael; Wiedorn, Max O.; Knoska, Juraj; Du, Yang; Gañán Riesco, Braulio; Herrada Gutiérrez, Miguel Ángel; López-Herrera Sánchez, José María; Cruz-Mazo, Francisco; Bajt, Saša; Montanero, J. M.; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos
Despite their fundamental and applied importance, a general model to predict the natural breakup length of steady capillary jets has not been proposed yet. In this work, we derive a scaling law with two universal constants to calculate that length as a function of the liquid properties and operating conditions. These constants are determined by fitting the scaling law to a large set of experimental and numerical measurements, including previously published data. Both the experimental and numerical jet lengths conform remarkably well to the proposed scaling law. This law is explained in terms of the growth of perturbations excited by the jet breakup itself.
Trajectory Planning for Spacecraft Rendezvous in Elliptical Orbits with On / Off Thrusters
(Elsevier, 2014) Vázquez Valenzuela, Rafael; Gavilán Jiménez, Francisco; Camacho, Eduardo F.; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos
In a previous work, the authors developed a trajectory planning algorithm for spacecraft rendezvous which computed optimal Pulse-Width Modulated (PWM) control signals, assuming that the target was moving in a circular Keplerian orbit. In this paper we extend the algorithm to the case of an elliptical target orbit with arbitrary eccentricity. Since the orbit is elliptical, the linear time-varying Tschauner-Hempel model is used, whose exact solution is possible by using true (or eccentric) anomaly instead of time (which is directly related to both via Kepler's equation). Unlike in the circular case, computing the PWM solution itself requires numerical integration. However, explicit linearization around the computed solution turns out to be possible and is exploited for rapidly improving the solution using linear programming (LP) techniques. The algorithm is initialized by solving the impulsive problem first; the impulses are converted to PWM signals, which are used as an initial guess. Using the explicit linearization and LP, the solution is refined until a (possibly local) optimal value is reached. The efficacy of the method is shown in a simulation study where it is compared to the impulsive-only approach.
Explicit boundary control of a reaction-diffusion equation on a disk
(Elsevier, 2014) Vázquez Valenzuela, Rafael; Krstic, Miroslav; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos
This paper introduces an explicit full-state boundary feedback law that stabilizes an unstable linear constant-coefficient reaction-diffusion equation on a disk. The backstepping method is used to design the control law. To apply backstepping the system is reduced to an infinite sequence of 1-D systems using Fourier series. H2 well-posedness and stability are proved, which implies that the solution is at least continuous on the disk.
Control of the longitudinal flight dynamics of an UAV using adaptive backstepping
(Elsevier, 2011) Gavilán Jiménez, Francisco; Acosta Rodríguez, José Ángel; Vázquez Valenzuela, Rafael; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos
An adaptive backstepping approach is used to control the longitudinal dynamics of an Unmanned Air Vehicle (UAV). The nonlinear controller designed makes the system follow references in the aerodynamic velocity and flight path angle, using the elevator deflections and the thrust as actuators. Moreover, the (global) solution is valid for all the flight envelope, since it is based on a general nonlinear model. The adaptation scheme proposed allowed us to design an explicit controller with a minimal knowledge of the aircraft aerodynamics. Simulations are included for a realistic UAV model that includes actuator saturation.
A Predictive Guidance Algorithm for Autonomous Asteroid Soft Landing
(Elsevier, 2018) Sánchez Merino, Julio César; Gavilán Jiménez, Francisco; Vázquez Valenzuela, Rafael; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos
The objective of this work is to present a closed-loop guidance algorithm for landing a probe on an irregular shaped rotating asteroid. The main assumption is that the spacecraft is orbiting close to the asteroid and has a continuous propulsion system enabling it to do a powered descent. The goal is to minimize fuel consumption while avoiding collision with the asteroid during the manoeuvre. This non-convex time-continuous optimal control problem is transformed to a convex static program by relaxing some constraints, discretizing and using an iterative method to handle with the asteroid gravity field non-linearities. Then, a guidance algorithm based on Model Predictive Control is applied with the purpose of coping with unmodelled dynamics and disturbances. Numerical results are showed and discussed.
A Flatness-Based Trajectory Planning Algorithm for Rendezvous of Single-Thruster Spacecraft
(Elsevier, 2018) Sánchez Merino, Julio César; Gavilán Jiménez, Francisco; Vázquez Valenzuela, Rafael; Louembet, Christophe; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos
This work presents a trajectory planning algorithm for spacecraft rendezvous with a passive target. The main assumption is that the chaser vehicle has a single thruster and an attitude control system (e.g. reaction wheels) providing the necessary torque to change its orientation, which may be the situation for small spacecraft or in the case of thruster failure. The goal is to design fuel-optimal manoeuvres while satisfying operational constraints. This time-continuous optimal control problem is addressed using the translational state transition matrix and the attitude flatness property to transform the dynamics into algebraic relations. Then, the problem is transformed to a non-linear programming problem which has to be solved. Simulation results are showed and discussed.
Volterra boundary control laws for a class of nonlinear parabolic partial differential equations
(Elsevier, 2004) Vázquez Valenzuela, Rafael; Krstic, Miroslav; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos
The efforts on boundary control of general classes of nonlinear parabolic PDEs with nonlinearities of superlinear growth have so far only resulted in counterexamples-results that show that finite time blow up occurs for large initial conditions even for simple cases like quadratic nonlinearities, with or without control. In this paper we present results identifying a class of systems that is stabilizable. Our approach is a direct infinite dimensional extension of the feedback linearization/backstepping approach and employs Volterra series nonlinear operators both in the transformation to a stable linear PDE and in the feedback law. While the full detail of our general approach is left for a future publication without a page limit, in this paper we give an example with explicit solutions for the plant/controller pair, including an explicit construction of the inverse of the feedback linearizing Volterra transformation. This, in turn, allows us to explicitly construct the exponentially decaying closed loop solutions. We include also a numerical illustration, showing blow up in open loop, and stabilization for large initial conditions in closed loop.
Bilateral boundary control of one-dimensional first- and second-order PDEs using infinite-dimensional backstepping
(Institute of Electrical and Electronics Engineers (IEEE), 2016) Vázquez Valenzuela, Rafael; Krstic, Miroslav; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos
This paper develops an extension of infinite-dimensional backstepping method for parabolic and hyperbolic systems in one spatial dimension with two actuators. Typically, PDE backstepping is applied in 1-D domains with an actuator at one end. Here, we consider the use of two actuators, one at each end of the domain, which we refer to as bilateral control (as opposed to unilateral control). Bilateral control laws are derived for linear reaction-diffusion, wave and 2 × 2 hyperbolic 1-D systems (with same speed of transport in both directions). The extension is nontrivial but straightforward if the backstepping transformation is adequately posed. The resulting bilateral controllers are compared with their unilateral counterparts in the reaction-diffusion case for constant coefficients, by making use of explicit solutions, showing a reduction in control effort as a tradeoff for the presence of two actuators when the system coefficients are large. These results open the door for more sophisticated designs such as bilateral sensor/actuator output feedback and fault-tolerant designs.
Output-feedback control of the longitudinal flight dynamics using adaptative backstepping
(Institute of Electrical and Electronics Engineers (IEEE), 2011) Gavilán Jiménez, Francisco; Vázquez Valenzuela, Rafael; Acosta Rodríguez, José Ángel; Universidad de Sevilla. Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos; Universidad de Sevilla. Departamento de Ingeniería de Sistemas y Automática
An adaptive backstepping approach is used to design an output feedback control law for the longitudinal dynamics of an Unmanned Air Vehicle (UAV). The resulting nonlinear controller makes the system to follow references in the aerodynamic velocity and flight path angle, using elevator deflections and thrust as actuators. Only measurable quantities are used in the control and adaptation laws. The proposed strategy allows to design an explicit controller without any knowledge of the aerodynamic coefficients or the trim angle of attack, which also depends on the aerodynamic coefficients; only well-known qualitative physical properties from aerodynamics are used. Simulations are included for a realistic UAV model including actuator saturation.

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