French Air Force Academy

Salon-de-Provence, France

French Air Force Academy

Salon-de-Provence, France
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Merheb A.-R.,Aix - Marseille University | Merheb A.-R.,Lebanese University | Noura H.,CNRS Systems and Information Sciences Lab LSIS | Bateman F.,French Air Force Academy
IEEE/ASME Transactions on Mechatronics | Year: 2017

In this paper, an emergency fault-tolerant controller is developed for quadrotor unmanned aerial vehicles (UAVs) suffering a total loss of one actuator (rotor/motor). The proposed controller is based on control allocation where the infected actuator is exempted from the control effect, and control efforts are redistributed among healthy actuators. As a result, the emergency controller transforms the infected quadrotor into a trirotor and uses the remaining actuators to ensure that the UAV continues following its path. The main advantage of the new controller is that it uses the same simple proportional-integral-derivative (PID) controller applied in fault-free cases by redistributing its controls, rather than designing complex and memory consumable controllers. Experimental results using the augmented reality (AR) Drone 2 platform show that by implementing the quadrotor to trirotor conversion maneuver, the nominal PID controller gains powerful fault-tolerant capabilities and the infected UAV is successful in maintaining its desired path. Performance degradation seen as oscillations did not cause the drone to crash despite the total loss of yaw control, the presence of activation delay, the nonsymmetric structure of the trirotor, and its odd number of rotors that produces imbalance of the rotor moments. © 1996-2012 IEEE.

Oumeziane A.A.,Aix - Marseille University | Parisse J.-D.,Aix - Marseille University | Parisse J.-D.,French Air Force Academy | Liani B.,Abou Bekr Belkaid University Tlemcen
48th AIAA Plasmadynamics and Lasers Conference, 2017 | Year: 2017

This work investigates the impact of the presence of doubly ionized species in a metallic plasma induced by an ultraviolet laser, while taking account the non equilibrium between electrons and heavy species. We developed a 1 D hydrodynamic model to describe the behavior of the laser induced plume, including the thermal non-equilibrium between electrons and heavy particles. Incorporating formation of doubly charged ions in such an approach has not been considered previously. This paper starts by a short introduction followed by a presentation of our model, computational code and the most significant results. Finally we present the main conclusions drawn from this investigation and some future perspectives. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

Bovet L.,French Air Force Academy | Bovet L.,MINES ParisTech Center of materials
Aerospace Science and Technology | Year: 2017

This note explores the optimization of thrust-vector angle for the cruise and initial climb phases of an airliner. For each performance, the lift coefficient and thrust-vector angle have been optimized simultaneously leading to a global optimum. However, the gain offered on the longitudinal performance by an ad-hoc inclination is limited. Finally, analytical expressions of the optimum thrust-vector angle have been derived for each performance, in complement to the expressions already provided by former studies on this subject. © 2017 Elsevier Masson SAS

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.

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

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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