French Air Force Academy

Salon-de-Provence, France

French Air Force Academy

Salon-de-Provence, France

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Marinus B.G.,Royal Military Academy | Personnettaz V.,French Air Force Academy | Hoarau V.,French Air Force Academy
International Review of Aerospace Engineering | Year: 2015

The influence of trailing-edge serrations on the steady flow around a propeller blade for a mini-remotely piloted aircraft is investigated. A reference blade operating at low advance ratio is modified with sawtooth and sine-wave serrations while maintaining a thin trailing edge in both instances. The distribution of the pressure and skin-friction load on the blade is studied as well as the details of the primary flow around the rotating blade, i.e. the axial and rotational components, and the secondary flow, i.e. the spanwise and cross-passage components resulting from the balance of the pressure gradient with the Coriolis and centripetal accelerations. The proposed serrations do not impact overall cruise performance such as propeller torque force and thrust and do not modify the primary or secondary flow fields. © 2015 Praise Worthy Prize S.r.l. - All rights reserved.

Bateman F.,Aix - Marseille University | Bateman F.,French Air Force Academy | Noura H.,United Arab Emirates University | Ouladsine M.,Aix - Marseille University
IEEE Transactions on Aerospace and Electronic Systems | Year: 2011

A fault detection and diagnosis (FDD) and a fault-tolerant control (FTC) system for an unmanned aerial vehicle (UAV) subject to control surface failures are presented. This FDD/FTC technique is designed considering the following constraints: the control surface positions are not measured and some actuator faults are not isolable. Moreover, the aircraft has an unstable spiral mode and offers few actuator redundancies. Thus, to compensate for actuator faults, the healthy controls may move close to their saturation values and the aircraft may become uncontrollable; this is critical due to its open-loop unstability. A nonlinear aircraft model designed for FTC researches has been proposed. It describes the aerodynamic effects produced by each control surface. The diagnosis system is designed with a bank of unknown input decoupled functional observers (UIDFO) which is able to estimate unknown inputs. It is coupled with an active diagnosis method in order to isolate the faulty control. Once the fault is diagnosed, an FTC based on state feedback controllers aims at sizing the stability domain with respect to the flight envelope and actuator saturations while setting the dynamics of the closed-loop system. The complete system was demonstrated in simulation with a nonlinear model of the aircraft. © 2006 IEEE.

Cagnac P.,French Air Force Academy | Di Noia N.,French Air Force Academy | Huang C.-H.,Agency for Science, Technology and Research Singapore | Racoceanu D.,French National Center for Scientific Research | Chaudron L.,ONERA
Proceedings of the International Joint Conference on Neural Networks | Year: 2011

A consciousness-driven visual attention model is presented in this paper. It is based on a bio-inspired computer fovea model and a hierarchical analysis for the given visual receptive field. Indeed, the bio-inspired computer fovea model is used to simulate the neural activity on the human visual system, and the hierarchical analysis provides a function to explore the information on the given visual scene. The proposed model can evaluate the contents on the scene and automatically highlights visually important regions. This model can be used in various applications, such as surveillance, visual navigation and target acquisition, etc. © 2011 IEEE.

Merheb A.-R.,Aix - Marseille University | Merheb A.-R.,Lebanese International University | Bateman F.,French Air Force Academy | Noura H.,United Arab Emirates University
2015 IEEE Conference on Control and Applications, CCA 2015 - Proceedings | Year: 2015

In this paper, Second Order Sliding Mode technique is used to develop a Passive Fault Tolerant Controller (PFTC) for octorotor UAVs. Super twisting algorithm is applied to form the discontinuous part of the controller. Optimal controller gains are found using Ecological Systems Algorithm, a bio-inspired optimization algorithm made to search within the stability region of the controller. An Active Fault Tolerant Controller (AFTC) version of the controller is designed using Pseudo-Inverse and Dynamic control re-allocation methods. SIMULINK based simulation results show the effectiveness of the proposed controllers which exceed the performance of First Order Sliding Mode active fault tolerant controller. © 2015 IEEE.

Merheb A.-R.,Aix - Marseille University | Noura H.,United Arab Emirates University | Bateman F.,French Air Force Academy
Conference on Control and Fault-Tolerant Systems, SysTol | Year: 2013

In this paper, two passive fault tolerant controllers based on Sliding Mode Control theory are designed for AscTec Pelican quadrotor. The first controller is a regular Sliding Mode Controller (SMC) that uses the robustness of SMC and its insensitivity to model uncertainties and disturbances to tolerate two different types of actuator faults. The latter controller is a cascaded SMC (CascSMC) with an inner loop fast SMC controlling the velocity system and tolerating its faults, and an outer loop SMC controlling the inner system (inner SMC and velocity system) with integrator. To tune the parameters of the controllers for their optimal values, a bio-inspired search algorithm called Ecological Search Algorithm (ESA) is used. SIMULINK results show that the proposed controllers are successful in controlling the quadrotor performing a helical path in the space in presence of two different actuator faults. Tests show that the cascaded SMC outperforms the regular SMC in handling tougher faults by compensating them quickly in its fast inner loop. © 2013 IEEE.

Marinus B.G.,Royal Military Academy | Maison J.,French Air Force Academy
Aerospace Science and Technology | Year: 2016

This article presents a semi-empirical model for fuel weight estimates based on mission requirements (i.e. payload and range), with the operating empty weight as parameter. The model applies to military turboprop transport aircraft, and is based on actual aircraft data. It is particularly suited for conceptual and preliminary design since it relies on the operating empty weight as sole parameter. The model is validated so it forms a sound and accurate alternative to the Breguet range equation. Empirical correlations are also proposed for the dependance upon the gross weight of the specific range and the fuel flow rate, along a flight at constant cruise altitude. © 2016 Elsevier Masson SAS

Merheb A.-R.,Aix - Marseille University | Merheb A.-R.,Lebanese International University | Noura H.,United Arab Emirates University | Bateman F.,French Air Force Academy
International Journal of Applied Mathematics and Computer Science | Year: 2015

In this paper, sliding mode control is used to develop two passive fault tolerant controllers for an AscTec Pelican UAV quadrotor. In the first approach, a regular sliding mode controller (SMC) augmented with an integrator uses the robustness property of variable structure control to tolerate partial actuator faults. The second approach is a cascaded sliding mode controller with an inner and outer SMC loops. In this configuration, faults are tolerated in the fast inner loop controlling the velocity system. Tuning the controllers to find the optimal values of the sliding mode controller gains is made using the ecological systems algorithm (ESA), a biologically inspired stochastic search algorithm based on the natural equilibrium of animal species. The controllers are tested using SIMULINK in the presence of two different types of actuator faults, partial loss of motor power affecting all the motors at once, and partial loss of motor speed. Results of the quadrotor following a continuous path demonstrated the effectiveness of the controllers, which are able to tolerate a significant number of actuator faults despite the lack of hardware redundancy in the quadrotor system. Tuning the controller using a faulty system improves further its ability to afford more severe faults. Simulation results show that passive schemes reserve their important role in fault tolerant control and are complementary to active techniques. © 2015 by Hassan Noura.

Pignatel F.,Northwestern University | Asselin C.,French Air Force Academy | Krieger L.,French Air Force Academy | Christov I.C.,Northwestern University | And 3 more authors.
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

The scaling properties of the continuous flowing layer in a quasi-2D circular tumbler half filled with a granular material are studied experimentally in the presence of three different interstitial fluids (air, water, and glycerine). In the dry case, the dimensionless flowing layer thickness δ 0/d scales with the dimensionless flow rate Qdry*=Q/(d√gd), where Q is the flow rate, d is the particle diameter, and g is the acceleration due to gravity, in agreement with previous studies. However, unlike previous studies, we show that the exponent for the power-law relation between the two depends on the range of Qdry*. Meanwhile, the angle of repose increases linearly with Qdry*. In the immersed case, the interstitial fluid changes the relevant time scales, which can be accommodated by considering the fluid properties. The result is that there are two different expressions for the dimensionless flow rate in the immersed flow; one corresponding to a free fall regime for a large Stokes number, and one corresponding to a viscous regime at small Stokes number. On this basis, a single dimensionless flow rate that incorporates both buoyancy and viscous friction is proposed. The effect of side walls is also investigated. For dry flows and those immersed in water, the thickness of the flowing layer decreases while the slope of the free surface increases as the gap separating the walls becomes smaller. For immersed granular flows with glycerine as the interstitial fluid, however, the ratio of the thickness of the flowing layer to the bead diameter is independent of the distance the between the side walls because viscous effects dominate. © 2012 American Physical Society.

Fan Y.,Northwestern University | Boukerkour Y.,French Air Force Academy | Blanc T.,French Air Force Academy | Umbanhowar P.B.,Northwestern University | And 2 more authors.
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

Segregation and mixing of granular mixtures during heap formation has important consequences in industry and agriculture. This research investigates three different final particle configurations of bidisperse granular mixtures-stratified, segregated and mixed-during filling of quasi-two- dimensional silos. We consider a large number and wide range of control parameters, including particle size ratio, flow rate, system size, and heap rise velocity. The boundary between stratified and unstratified states is primarily controlled by the two-dimensional flow rate, with the critical flow rate for the transition depending weakly on particle size ratio and flowing layer length. In contrast, the transition from segregated to mixed states is controlled by the rise velocity of the heap, a control parameter not previously considered. The critical rise velocity for the transition depends strongly on the particle size ratio. © 2012 American Physical Society.

News Article | January 29, 2016

The UTEP AGENT system was created to study understanding between embodied conversational agents (ECAs) and humans, with emphasis on the effects of paralinguistic behaviors on engagement and rapport. Paralinguistics includes behaviors such as gesture, intonation and rhythm in speech, gaze and turn taking. The team's research includes work on personality traits of humans and agents. In "Survival on Jungle Island," the ECA and a human interact, using speech and gesture, in a 40-60 minute adventure composed of 23 scenes. A study conducted with the adventure showed that rapport increases when the ECA asks the human to perform task-related gestures and then perceives a human performing these gestures. In the jungle adventure, the system simulates a survival scenario in which the player interacts with the ECA, Adriana. In order to survive, both human and ECA must collaborate, cooperate and build a relationship. The game begins with a cinematic sequence of a stormy shipwreck, providing background information as to how the person ended up in the survival situation. This scene is followed by another two scenes, which serve as an inconspicuous tutorial to avoid breaking the impression of an immersive reality. The first scene contains personal questions that let the player and the ECA get to know each other, giving the impression that Adriana is processing what she hears. The second scene moves the story forward by providing an explanation as to how the ECA Adriana has survived in the jungle so far, and shows that she reacts to the player's responses. At the end of the scene, the story continues to develop depending on the player's choice of what to do next. Novick created the system with the help of his Advanced aGent ENgagement Team (AGENT), comprising postdoctoral fellow Ivan Gris; UTEP undergraduate and graduate students Adriana Camacho, Alex Rayon, Joel Quintana, Anuar Jauregui, Timothy Gonzales, Alfonso Peralta, Victoria Bravo, Jacqueline Brixey, Yahaira Reyes and Paola Gallardo; French Air Force Academy cadets Guillaume Adoneth and David Manuel; and El Paso high school students Brynne Blaugrund and Nick Farber. To enable the interaction between humans and ECAs, the team combined the use of Unity 4, an animation software; a Microsoft Kinect motion sensing device; and the Windows Speech SDK software. The team also built "middleware," which enabled more rapid development of applications including the jungle adventure. The UTEP AGENT system recently received the award for Outstanding Demonstration at the 17th ACM International Conference on Multimodal Interaction held in November in Seattle, Washington. "UTEP's virtual-agent team now ranks among the best in the world," Novick said. "We are both building exciting new virtual-agent technology and learning how to make agents more adaptable to humans."

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