Valéry Bourny

Voltage noise across a metal/metal sliding contact as a probe of the surface state

We report a complete experimental study and a physical modelling of the long-term evolution of the main electrical properties of a metal ring/wire sliding contact, the wire, and the ring being coated with a thin Au film. The long-term evolution of the Au/Au sliding contact was characterized through the measurement and tracking of relevant quantities such as the voltage noise across the contact, revealing the ageing of the contact. A phenomenological approach to the sliding contact, coupling both electrical and mechanical aspects, allows a sensible interpretation of the experimental results. This approach retains three contributions to the voltage noise operating at different scales, namely the rings surface geometry, chemical composition fluctuations of the coated rings, and the mesoscopic structure of the contact. A fundamental distinction between these sources is established, owing to their effects relying on either the mechanical contact losses or resistance fluctuations. We finally show that the deter...

A localization system based on buried magnets and dead reckoning for mobile robots

Localization problems are key concerns in the design of truly autonomous robots. If a robot does not know where it is, it will not be able to determine what to do next properly. In order to localize itself, a robot can use both relative and absolute measurement systems to get feedback about its driving actions and the environment perception. Usually, absolute localization is used periodically to correct drifts of relative localization performed with odometers, or inertial sensors. This absolute localization has to be as accurate as possible to give the robot the most reliable information on its position especially in docking situations. In this paper, we describe an absolute localization system able to determine the robots position thanks to a magnet inserted into the ground. We have used a triangulation method to compute the position of the robot which provided us static and dynamic localization. This system has been embedded in an Auto Guided Vehicle (AVG) in an industrial context.

Signal processing algorithm on a low resource processor: DTMF strings identification on a DIL8 package microcontroller

In this paper we describe a low cost embedded system integrating all the functionalities needed for the analogical processing of radio communication transponder. We particularly put the emphasis on the optimized algorithm of tone and DTMF (dual tone multiple frequencies) detection in a DIP 8 microcontroller with only 64 bytes of RAM. We also present all the limits and the main advantages of our solution compared at other analogical solutions.

Multi-Scale and Multi-Physics Modeling of the Contact Interface Using DEM and Coupled DEM-FEM Approach

Abstract: This chapter presents the description of physical phenomena in the context of the modeling of the contact interface behavior based on discrete element method (DEM) and coupled DEM–finite element method (DEM–FEM) approach. Our interest in this area, which is related to several engineering applications where the contact interface plays a significant role, is prompted by the desire to understand the mechanisms that involved multi-physics coupling and how these influence the studied system from mechanical, thermal or electrical behavior point of view. Obviously, it is not easy to summarize all applications involving the contact interfaces, nevertheless, through those given as examples in the following sections, we have tried to highlight the relevance of a multi-scale and multi-physics approach with the aim of a modeling as close as possible to the microscale.

New procedure for re-machining in high speed machining processes based on a DSP architecture

This paper presents a new method implemented in an embedded system to detect the first contact between the rotating tool and the surface of the workpiece in the high speed machining operations with a high degree of accuracy. This method is based on the measurement of impedance variations and the calculation of a correlation function. This embedded system associated with the machining process ensures not only the geometrical quality of machined surfaces but also to avoid measuring the tool with tool touch probe, which allows to compensate the tool wear. The purpose of this project is to hold together the world of embedded and the machine world and make an industrial demonstrator integrating different features developed.

Technological leap of signal transfer system: CONTACTLESS

Renewable energies are at the heart of discussions and wind energy even more. A wind turbine is composed of more than 9 000 parts each having a low or high level of criticality. In this work, we are interested in a study of a critical system of wind turbines: the Signal Transfer System, also commonly call slip ring: it is an electromechanical system whose function is to transmit information/data (sensors and actuators) between a stator and a rotor, by sliding contact. Requiring periodic maintenance to relubricate the system, and using noble materials, this system is getting more and more expensive, thus alternatives are seeked. The aim of CONTACTLESS is to suppress this sliding contact (an increase in the costs of raw materials) by an embedded system using wireless technology. A first demonstrator has been realized in 2011. It presents the first work realized allowing grouping and the transfer of information in wireless mode from a high data rate wire protocol (CAN bus) to a low data rate wireless technology (Zigbee) to validate our approach of level operational phase of OSI layer model (encapsulation/decapsulation).