Modelling, Analysis and Control of OmniMorph: an Omnidirectional Morphing Multi-rotor UAV

This paper introduces for the first time the design, modelling, and control of a novel morphing multi-rotor Unmanned Aerial Vehicle (UAV) that we call the OmniMorph. The morphing ability allows the selection of the configuration that optimizes energy consumption while ensuring the needed maneuverability for the required task. The most energy-efficient uni-directional thrust (UDT) configuration can be used, e.g., during standard point-to-point displacements. Fully-actuated (FA) and omnidirectional (OD) configurations can be instead used for full pose tracking, such as, e.g., constant attitude horizontal motions and full rotations on the spot, and for full wrench 6D interaction control and 6D disturbance rejection. Morphing is obtained using a single servomotor, allowing possible minimization of weight, costs, and maintenance complexity. The actuation properties are studied, and an optimal controller that compromises between performance and control effort is proposed and validated in realistic simulations

Libbraille : a portable library to easily access Braille displays

Abstract: The TiM project intends to develop and to adapt computer games for visually impaired children. In order to achieve this project a library which allows to easily access Braille displays was developed. This library provides all the functions needed to write text on the Braille display, directly raise Braille dots as well as receive the keys pressed on it. On top of that this library works with many different types of displays and is freely reusable. Introduction The TiM Project The overall purpose of the TiM project (Tactile Interactive Multimedia computer games for visually impaired children) To reach the needs of the children aimed by the TiM project, the platform is able to render those games to all the specific devices they use, each are corresponding to a specific modality: tactile boards, Braille displays, speech synthesizers and customizable graphical displays (scalable font prints, adjustable colors and contrast...) Support of Braille Displays An important issue for the TiM project is to supply the support for as many existing models of Braille displays as possible, that are used currently and that each child may have, as well as being able to add drivers easily when a new model comes on the market. Indeed, Braille displays are generally extremely expensive (starting at 5000€). It makes it very difficult for organizations to have several different models to develop drivers and for users to buy a different model. Since there was no existing standard library to access Braille displays, it appeared that the development of a Braille library, Libbraille, was crucial for the TiM project. A Collaborative Approach The high cost of Braille devices, and the fact that many manufacturers do not release publicly the protocol of their devices, explain that there was no standard API for Braille displays. A way to bypass this problem appeared to make this a collective project. By allowing other people to use and improve the library to suit their own needs, we could share our improvements and finally correctly support a large number of devices. That is why the code of the library was released under the LGPL [LGPL] which is used by many projects including the famous GNU/Linux. This allows people to freely copy, distribute and/or modify the library as long as they provide their enhancements under the same license. Developers who want to use the library can freely link it to their programs without any restriction. The library was also designed so that it could be as generic as possible. This means that it should be used in any project that requires Braille functionalities. Indeed other projects had already been done that used Braille displays. Some like BRLTTY [BRLTTY] or BRASS [BRASS], where quite advanced, however they were complete screen readers and the Braille functionalities were not independent, so that it was very hard to reuse them in other projects. The protocols used in those programs were integrated in Libbraille when the license allowed that, but with a focus on re-usability. Features of the Library This library is responsible for all the low level interactions with Braille displays. Text can simply be written on the display, or Braille dots can even be directly raised independently. It is also possible to get the keys that have been pressed by a user when the device has such keys. Supported Displays Here Architecture The library is organized in a modular way. A first layer provides a simple API to developers through a set of functions starting with the braille_ prefix, like braille_init, braille_display or braille_read. At initialization and according to a configuration file, this first layer will load a device dependent module. This module implements the low level interaction with a given Braille terminal protocol and depends on the manufacturer and model of Braille terminal. This module must use a lower level layer that provides a set of common portable functions to all drivers in order to communicate through the serial port or the usb bus, or to log some debug information. Those low level functions are portable and simplify a lot the development of drivers that work on different operating systems. Internationalisation The TiM projects aims to access the widest possible concerned population, and in this focus, multilingual features has been integrated from the beginning of the development. Many different Braille tables are used in different countries and even among different users of the same country! Those tables make the link between the ASCII and Braille representation of a character. The library already supports the ability to switch between many different tables and a user can easily create his own. Virtual Driver A graphical virtual driver was developed which displays a virtual Braille keyboard on the screen. This allows developers to create Braille enabled programs, without owning an expensive Braille terminal for test purpose. Configuration of Keys Layout This features allow users to customize the layout of keys on the Braille keyboard by editing a configuration file and to switch between some configurations at runtime. This can be very convenient for users since then can have different key layout depending on the software or the context on which they are working. Usage Overview Initialisation and Closing Interaction with the Braille library is done through functions starting with the braille_ prefix 1 . Those functions are declared in the braille.h header. The braille_init function should be called before any other function of the library. It will load the correct driver then initialise and configure the Braille display. On the other side, the braille_close function must always be called when closing the Braille library. It will unload the driver, free resources and close the library. Displaying a Simple String The simplest way to write something on the Braille display is to use braille_display. It must be called with a string and will display that string on the display. braille_display("test started"); When displaying text, the Braille representation is calculated according to a Braille table which can be customized by the user. Advanced dots displaying There is a more complex function to display when a better control of what is displayed is necessary, for example when displaying something other than text. What will be displayed is a combination of text and a filter that directly manipulate dots, using the braille_filter and braille_render functions. Typing with the Braille Keyboard It is also possible to know which keys have been pressed on the Braille display with the braille_read function. This function returns a structure of type brl_key. This structure has an attribute named type concerning the type of key pressed. If this type is BRL_CURSOR, the code attribute contains the number of the pressed cursor routing key starting at 0. If the type is BRL_CMD, then a function key has been pressed on the Braille display. The code attribute contains a code depending on the function key. There are many codes which 1 The source code of a complete example is available in the annexes. can be found in the braille.h header file. If the type is BRL_KEY, then the user has pressed a standard ASCII code on its Braille display. The code attribute gives the ASCII value. Current Status and Further Works Libbraille is already a well working library used in different projects requiring Braille displays support. The Free Software model appeared to be an excellent model for the development of devices drivers and many users contributed to the project. Indeed other libraries were created following the same model for the TiM project (libspeech which can drives some speech synthesis and libboard a driver for tactile boards). The library is far however from supporting all the existing models of Braille displays. This can only be achieved if this library is advertised enough so that owners of those devices can collaborate to improve the library... The following enhancements are also planned to be included in libraille: • Support for more models of displays: it depends on the collaboration of people with those models or of manufacturers. The integration of recent USB models is currently under development. • Development of a simple configuration front-end: at this time, the focus has mostly been on the developer aspect of the library. It is planned to improve the user friendliness by adding a simple configuration back-end to configure the device model and the key layout. More information can be found at: http://libbraille.org Acknowledgement

Kim Brandt, Kingdom of Beauty: Mingei and the Politics of Folk Art in Imperial Japan (Le royaume de la beauté : le Mingei et la politique de l’art populaire dans le Japon impérial)

L’exposition proposée par le Musée du quai Branly en 2008-2009 sur les objets et l’esthétique mingei a donné l’occasion de parcourir les derniers ouvrages parus sur le sujet. La monographie de Kim Brandt, professeure associée en histoire japonaise à l’Université Columbia, mérite sa place parmi ces lectures. Chronologiquement organisé, Kingdom of Beauty expose l’histoire du mouvement pour les Arts populaires de ses origines, dans les années 1920, à la fin de la Seconde Guerre mondiale, en lien..

On the interaction between quasilinear elastodynamics and the Navier-Stokes equations

The interaction between a viscous fluid and an elastic solid is modeled by a system of parabolic and hyperbolic equations, coupled to one another along the moving material interface through the continuity of the velocity and traction vectors. We prove the existence and uniqueness (locally in time) of strong solutions in Sobolev spaces for quasilinear elastodynamics coupled to the incompressible Navier-Stokes equations along a moving interface. Unlike our approach for the case of linear elastodynamics, we cannot employ a fixed-point argument on the nonlinear system itself, and are instead forced to regularize it by a particular parabolic artificial viscosity term. We proceed to show that with this specific regularization, we obtain a time interval of existence which is independent of the artificial viscosity; together with a priori estimates, we identify the global solution (in both phases), as well as the interface motion, as a weak limit in srong norms of our sequence of regularized problems.Comment: 43 pages, to appear in Archive for Rational Mechanics and Analysi

Survey on Aerial Multirotor Design: a Taxonomy Based on Input Allocation

This paper reviews the impact of multirotor aerial vehicles designs on their abilities in terms of tasks and system properties. We propose a general taxonomy to characterize and describe multirotor aerial vehicles and their design, which we apply exhaustively on the vast literature available. Thanks to the systematic characterization of the designs we exhibit groups of designs having the same abilities in terms of achievable tasks and system properties. In particular, we organize the literature review based on the number of atomic actuation units and we discuss global properties arising from their choice and spatial distribution in the designs. Finally, we provide a discussion on the common traits of the designs found in the literature and the main future open problems

Some Results on the Boundary Control of Systems of Conservation Laws

This note is concerned with the study of the initial boundary value problem for systems of conservation laws from the point of view of control theory, where the initial data is fixed and the boundary data are regarded as control functions. We first consider the problem of controllability at a fixed time for genuinely nonlinear Temple class systems, and present a description of the set of attainable configurations of the corresponding solutions in terms of suitable Oleinik-type estimates. We next present a result concerning the asymptotic stabilization near a constant state for general $n\times n$ systems. Finally we show with an example that in general one cannot achieve exact controllability to a constant state in finite time.Comment: 10 pages, 4 figures, conferenc

Maximes = Maximen. - Zweisprachig: Französisch / Deutsch

Die Marquise de Sablé war zur Zeit Ludwigs XIV. eine der bedeutendsten Damen der tonangebenden Gesellschaft. Sie führte einen Salon, fühlte sich zum Jansenismus hingezogen, war äußerst gebildet und eine enge Vertraute La Rochefoucaulds. Ihre nachgelassenen Maximen bieten einen Querschnitt durch das psychologische Wissen und die gesellschaftlichen Normen der Epoche. Sie wurden für die Bamberger Ausgabe nach 250 Jahren erstmals wieder ins Deutsche übertragen

Synthesis of azafluorenones and related compounds using deprotocupration-aroylation followed by intramolecular direct arylation

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.International audienceThe efficiency of the deprotocupration-aroylation of 2-chloropyridine using lithiocuprates prepared from CuX (X=Cl, Br) and LiTMP (TMP=2,2,6,6-tetramethylpiperidido, 2 equiv) was investigated. CuCl was identified as a more suitable copper source than CuBr for this purpose. Different diaryl ketones bearing a halogen at the 2 position of one of the aryl groups were synthesized in this way from azines and thiophenes. These were then involved in palladium-catalyzed ring closure: substrates underwent expected CH-activation-type arylation to afford fluorenone-type compounds, and were also subjected to cyclization reactions leading to xanthones, notably in the presence of oxygen-containing substituents or reagents

The boundary Riemann solver coming from the real vanishing viscosity approximation

We study a family of initial boundary value problems associated to mixed hyperbolic-parabolic systems: v^{\epsilon} _t + A (v^{\epsilon}, \epsilon v^{\epsilon}_x ) v^{\epsilon}_x = \epsilon B (v^{\epsilon} ) v^{\epsilon}_{xx} The conservative case is, in particular, included in the previous formulation. We suppose that the solutions $v^{\epsilon}$ to these problems converge to a unique limit. Also, it is assumed smallness of the total variation and other technical hypotheses and it is provided a complete characterization of the limit. The most interesting points are the following two. First, the boundary characteristic case is considered, i.e. one eigenvalue of $A$ can be $0$. Second, we take into account the possibility that $B$ is not invertible. To deal with this case, we take as hypotheses conditions that were introduced by Kawashima and Shizuta relying on physically meaningful examples. We also introduce a new condition of block linear degeneracy. We prove that, if it is not satisfied, then pathological behaviours may occur.Comment: 84 pages, 6 figures. Text changes in Sections 1 and 3.2.3. Added Section 3.1.2. Minor changes in other section