Model Predictive Control Allocation of Systems with Different Dynamics

International audienceSeveral systems are integrated in passenger cars. Some of them are just redundant systems due to safety requirements. Others, are completely different and can interact with each other as long as they are operating inside the same vehicle. Control allocation methods have been successfully implemented in advanced aircrafts to avoid conflicts, especially in the context of redundant systems. In this paper, we will rather focus on coordinating non-redundant advanced chassis systems with different dynamics. This difference in dynamics can be especially problematic when systems exhibit different communication delays. Model Predictive Control Allocation (MPCA) methods are therefore investigated in order to activate the right system at the right moment. Results show that particularly when the most effective system is saturated, another system with a different time delay can be activated few steps before saturation to instantly take over the maneuver. With good knowledge of actuator dynamics and higher computation power, MPCA methods are able to solve complex problems in severe situations

Adaptive Robust Vehicle Motion Control for Future Over-Actuated Vehicles

International audienceMany challenges still need to be overcome in the context of autonomous vehicles. These vehicles would be over-actuated and are expected to perform coupled maneuvers. In this paper, we first discuss the development of a global coupled vehicle model, and then we outline the control strategy that we believe should be applied in the context of over-actuated vehicles. A gain-scheduled H ∞ controller and an optimization-based Control Allocation algorithms are proposed. High-fidelity co-simulation results show the efficiency of the proposed control logic and the new possibilities that could offer. We expect that both car manufacturers and equipment suppliers would join forces to develop and standardize the proposed control architecture for future passenger cars

Propagation of acoustic waves in two waveguides couples by perforations. I. Theory.

International audienceThe problem of propagation in two guides coupled by perforations, important for a perforated tube muffler, is discussed. At low frequencies, if the distance between perforations is sufficiently large, a discrete model can be used. An exact equivalent circuit for a perforation is obtained by using a modal theory and a matrix formalism. A series inductance due to the existence of antisymmetric field in the perforation is proven to exist, completing the perforation shunt impedance concept. This model is directly exploitable for lattice analysis. For homogeneous lattices (i.e. with identical propagation in the two guides), either regular or irregular, two modes exist: a planar mode and a "flute" mode, either propagating or evanescent. Cutoff frequencies of periodic lattices are found to depend on either the shunt inductance or the series inductance (the first cutoff depending on the shunt one). In homogeneous lattices, a new type of evanescent waves can exist, with non-zero energy flux, equal and opposite in sign in each guide. Finally, the effect of mean flow in such a lattice is discussed

Combined Source and Channel Strategies for Optimized Video Communications

ISBN 978-953-7619-70-

Question sur la Question (QsQ5) : les pouvoirs d’instruction des juridictions constitutionnelles et la formation de l’intime conviction des juges constitutionnels

La 5ème édition de la « Question sur la Question » s’intéresse au processus antérieur à la décision du juge constitutionnel pour essayer de décrypter ce qui, dans ce processus, contribue à former l’intime conviction du juge constitutionnel. La réflexion s’appuie sur une lecture comparatiste des expériences constitutionnelles. Le jugement de constitutionnalité est apprécié en tant que processus factuel déterminé et affecté par un ensemble d’éléments juridiques ou non. L’étude de la procédure d’instruction et les différents pouvoirs qui en découlent au profit des juridictions constitutionnelles permet dans un premier temps de mettre en évidence ce que signifie « instruire » pour une juridiction constitutionnelle, quels sont les pouvoirs qui s’y rattachent et qui instruit au sein de la juridiction. Dans un second temps, il s’agit, de manière plus analytique, d’envisager chacun des éléments, mis en évidence le cas échéant durant l’instruction, susceptibles de former l’intime conviction des juges constitutionnels : du justiciable à la doctrine, en passant par le législateur ou le juge constitutionnel lui-même. Ces premières lectures comparatistes doctrinales sont éclairées par l’expérience des juges constitutionnels eux-mêmes

Question sur la Question (QsQ5) : les pouvoirs d’instruction des juridictions constitutionnelles et la formation de l’intime conviction des juges constitutionnels

La 5ème édition de la « Question sur la Question » s’intéresse au processus antérieur à la décision du juge constitutionnel pour essayer de décrypter ce qui, dans ce processus, contribue à former l’intime conviction du juge constitutionnel. La réflexion s’appuie sur une lecture comparatiste des expériences constitutionnelles. Le jugement de constitutionnalité est apprécié en tant que processus factuel déterminé et affecté par un ensemble d’éléments juridiques ou non. L’étude de la procédure d’instruction et les différents pouvoirs qui en découlent au profit des juridictions constitutionnelles permet dans un premier temps de mettre en évidence ce que signifie « instruire » pour une juridiction constitutionnelle, quels sont les pouvoirs qui s’y rattachent et qui instruit au sein de la juridiction. Dans un second temps, il s’agit, de manière plus analytique, d’envisager chacun des éléments, mis en évidence le cas échéant durant l’instruction, susceptibles de former l’intime conviction des juges constitutionnels : du justiciable à la doctrine, en passant par le législateur ou le juge constitutionnel lui-même. Ces premières lectures comparatistes doctrinales sont éclairées par l’expérience des juges constitutionnels eux-mêmes

Adhesively Bonded FRP Reinforcement of Steel Structures: Surface Preparation Analysis and Influence of the Primer

International audienceAbstract In tropical areas, with marine environment, high temperature and humidity, corrosion is a constant threat. The maintenance of steel structures (like FPSO’s) is becoming a challenge. The current technique of “crop and renewing” repair involves a certain number of major issues for project owners such as: “hot work”, that is to say welding; temporary weakening of the structure; need to empty, clean and purging the oil tanks of the FPSO’s, resulting in long downtime and an expensive solution. “Cold repair”, such as composite repair, is a promising solution. However, surface preparation and the influence of the primer are crucial issues to be addressed to ensure the strength and reliability of this type solution based on bonded patch. The paper presents an experimental study of the influence of the surface preparation and the primer on the strength of small steel bonded specimens which have been deliberately degraded by corrosion and pollution. Several surface preparation methodologies were investigated and the quality of these preparations was assessed using methods that can be implemented on site. Two main aspects were investigated: the detection of the residual presence of pollutants through the use of a portable infrared spectrometer; and the determination of surface energy after preparation using contact angle and wettability measurement equipment. To study the impact of the primer on the adhesion capacity of the steel surface, critical toughnesses measurements was performed with End notch flexure tests. Three configurations have been tested: bonding with the epoxy resin without initial application of primer and bonding with the Epoxy resin with initial application of two Primer A and B. The results shown clearly that the type of primer and the quality of its application are paramount importance to ensure the strength of steel bonded patches

Use of Distributed Optical Fibre to Monitor the Crack Propagation of an Adhesively Bonded Joint During an ENF Test

International audienceThe floating production, storage and offloading units (FPSO) being generally in a tropical area, makes corrosion a fundamental ageing problem of these steel structures. Therefore, there is a strong need for proposing repair solutions having low impact on their exploitation. The owner of these units are highly interested in the development of "cold repair" in contrast with "hot works" which require to stop the production for security risks, like adhesively bonded FRP (Fibre Reinforced Polymer) patch which requires additional development, in particular in the design step. The design of these reinforcements needs a complete understanding of the mechanical state of the patch which is based on the different materials and interfaces properties. Fracture mechanics seems an interesting option to express the mechanical state of the patch and more particularly the risk to undergo interlaminar fracture or steel interface debonding failure before materials failure. The experimental definition of the required design values for such an approach (critical toughnesses) are generally obtained with common tests such as DCB or ENF tests. The presented study is focused on the determination of the critical toughness in mode II through ENF (End Notched Flexure) test which can be done following some standards, such as ASTM D7905. A distributed optical fibre was used to verify the correct determination of the initial crack length, to determine the crack propagation during the test, and to monitor the fracture process zone length. The currently used methods, such as visual observation or Digital Image Correlation (DIC) of the crack front at the border of the sample, may indeed induce error if the crack is not straight. To compare these methods, the realized test was monitored using a distributed optical fibre placed in the centre of the lap width, in and on the specimen. Firstly, the issues related to the integration of this continuous optical fibre will be raised (insertion, precision resolution, measurement noise). Then, some experimental investigations will be described presenting different monitoring strategies using continuous optical fibre measurement and Digital Image Correlation technique (DIC). The obtained results will be analyzed focusing on the proper determination of the critical toughness of the adhesive. This will then be used to design and optimize the monitoring strategy of a wider experimental campaign

Use of high spatial resolution distributed optical fiber to monitor the crack propagation of an adhesively bonded joint during ENF and DCB tests

International audienceSimilarly to other industrial areas, there is a strong interest for the use of bonded FRP (Fiber Reinforced Polymers) repair or reinforcement for steel structures in the case of offshore applications. However, the reliability of the adhesively bonded (FRP) shall stand as high as steel renewal, this requires additional developments, in particular, a complete understanding of the repair mechanical strength which depends on material and interfacial properties. Fracture mechanics is an interesting approach to assess the risk to undergo interlaminar fracture or steel to adhesive interfacial disbonding failure. The experimental determination of the required design values for this an approach (critical toughness) are generally obtained using common tests such as Double Cantilever Beam (DCB), End Notched Flexure (ENF) or Mixed Mode Bending (MMB) tests. These tests require a precise crack length monitoring that is currently carried out using visual observation or Digital Image Correlation (DIC) on the flank of the sample. This may induce error in crack length measurement especially if the crack doesn't remain straight during the test. The paper presents a study of crack front monitoring by a distributed optical fiber as an alternative to the standard techniques to monitor crack front and to determine the critical toughness in mode I and II through respectively, DCB (Double Cantilever Beam) and ENF (End Notched Flexure) tests. Firstly, the issues related to the use of this continuous optical fiber are raised (insertion, precision resolution, measurement noise, exploitation methodologies). Then, some experimental investigations on ENF and DCB tests are presented and analyzed using the proposed methodology to monitor crack propagation using the optical fiber strain measurement. The obtained results are compared, focusing on the proper determination of the critical toughness of the adhesive. These results show that an optical fiber bonded on the surface of the sample can be used to measure and follow the crack propagation during the test which simplifies and adds precision to the standardize critical toughness computation method

Insects and incest: sib-mating tolerance in natural populations of a parasitoid wasp

International audienc