Betty Lemaire-Semail

Squeeze film effect for the design of an ultrasonic tactile plate

Most tactile displays currently built rely on pin-based arrays. However, this kind of tactile device is not always appropriate when we need to give the illusion of finely textured surfaces. In this paper, we describe the squeeze film effect between a plate and a finger, and we use this effect to design an ultrasonic tactile plate. The plate is actuated by piezoelectric ceramics. Ultrasonic vibrations are thus produced and are capable of generating the squeeze film effect. This enables us to simulate variable friction on the surface of the plate. In order to identify the squeeze film phenomenon, this study considers the case where a finger, with a planar bottom surface and with epidermal ridges, is placed on a rapidly vibrating plate. The overpressure is calculated and the result enables us to assess the relative coefficient of friction as a function of the vibration amplitude of the plate. Based on this principle, and using both analytic and FE method studies, and given ergonomic and stimulation (squeeze film) requirements, we show that it is possible to design a tactile plate which is capable of giving programmable tactile sensations. We conclude by comparing the results obtained from our simulations with experimental results.

Inversion-based control of electromechanical systems using causal graphical descriptions

Causal ordering graph and energetic macroscopic representation are graphical descriptions to model electromechanical systems using integral causality. Inversion rules have been defined in order to deduce control structure step-by-step from these graphical descriptions. These two modeling tools can be used together to develop a two-layer control of system with complex parts. A double-drive paper system is taken as an example. The deduced control yields good performances of tension regulation and velocity tracking

Energetic Macroscopic Representation and Inversion-Based Control Illustrated on a Wind-Energy-Conversion System Using Hardware-in-the-Loop Simulation

Study of a wind-energy-conversion system (WECS) is a very attractive topic for students. The analysis of an entire WECS requires knowledge of different scientific fields, which are of interest for future engineers. In this paper, energetic macroscopic representation is used to describe a complete WECS. This synthetic graphical tool yields a natural decomposition of the studied WECS with respect to physical laws. Moreover, a control scheme is easily deduced from this description using inversion-based rules. Thus, maximum-power point-tracking strategies and drive controls can be defined. The simulation of the studied WECS is directly transposed to Matlab-Simulink. Moreover, a hardware-in-the-loop simulation of the WECS is studied using an actual induction generator and an electrical drive to simulate the wind turbine. This graphical methodology is used in the electrical engineering Masters degree at the University of Lille (France).

Hardware-in-the-loop simulation of electric vehicle traction systems using Energetic Macroscopic Representation

A hardware-in-the-loop (HIL) simulation of an electric vehicle traction system is developed for experimental validations of electrical drives. Energetic macroscopic representation is used to organize the numerous blocks required. A classical 2-driven-wheels traction is studied with an induction machine. The HIL is based on a controlled DC drive, which imposes the same behavior of the mechanical power train to the induction machine. A flexible and dynamical model of the whole system is used and experimental results are provided

Design of a transparent tactile stimulator

This paper presents the design of a transparent tactile stimulator, based on the friction reduction between the fingertip and the active surface. With such a design, the ratio between the useful area (i.e. the active display and the tactile area) and the device face is equal to 0.7, while the touched areas size is 93mm×65mm. Key design procedure is given, and experimental results are presented.

Merging two tactile stimulation principles: electrovibration and squeeze film effect

Electrovibration and squeeze film effect can modify the perception a user has of a flat surface. These two stimulation principles are compatible, which means that they can be used at the same time on the same tactile stimulator. This paper first highlights the differences between the two principles, then gives experimental results obtained when merging, with specific conditions, these two stimulation principles.

Comparison of Different Models and Simulation Approaches for the Energetic Study of a Subway

This paper compares different models and simulation approaches for an energetic simulation of an automatic subway. For this purpose, several models are carried out from a dynamic model, which is validated by comparison with experimental measurements. Furthermore, two different simulation approaches are compared, i.e., backward and forward approaches. A simplified model is obtained and allows the reduction of the simulation time by 96 compared with the dynamic model by keeping an accuracy value of more than 99%.

Electrovibration Modeling Analysis

Electrostatic attraction may be used to modulate the apparent friction coefficient between two surfaces. Applied to the human finger and a polarized interface, the principle can modify the user perception of the interface surface. In this paper, the different steps towards the modeling of the electrovibration phenomenon are developed. An investigation on the current modeling will be carried out, with a focus on the temporal evolution and frequency dependence of the stimulus. Thus, an improvement of the modeling will be proposed to take into account this major effect, and then, it will be checked with an experimental setup and compared with literature results. The last few years have seen an increasing interest for haptic stimulation and simulation. Different technologies are available to provide a tactile feedback to a user by modifying his perception of a surface. In particular, it is possible to control the friction between a surface and a finger thanks to squeeze film effect or to electrovibra-tion. This study is focused on the electrovibration effect: the modulation of the perceived friction coefficient due to the induced electrostatic force between a finger and a high voltage supplied plate [1]. The effect is known since the mid fifties [2], but the interest has raised only recently. Firstly, spatial division of electrode was developed to provide precise and complex stimulus pattern of conductive pads, but this solution suffered from its complexity and turned out difficult to apply [5]. Recently, electrovi-bration took advantage of technological improvements of fingertips position sensor based on optical or resistive solutions. The possibility to track precisely the position of the finger leads to fine gratings simulation thanks to spatial-stimulus relation. With spatio-temporal transformation, the stimulator itself becomes easier to manufacture and it becomes possible to produce tactile feedback on transparent surfaces [1] or merge it with another tactile stimulation technique [3]. If the efficiency of the process to provide successful tactile feedback is clear, the physical modeling of the phenomenon involving the finger is not yet satisfactory. The

Experimental evaluation of friction reduction in ultrasonic devices

Previously proposed models of the ultrasonic lubrication of a finger mediated by flat surfaces are not consistent with the experimental results for vibrational amplitudes greater than a few microns. This paper presents experimental data acquired through a dedicated tribometer and proposes an experimental model of ultrasonic lubrication at high vibrational amplitudes.

Physical and Perceptual Independence of Ultrasonic Vibration and Electrovibration for Friction Modulation

Two different principles are available to modulate the user perceived roughness of a surface: electrovibration and ultrasonic vibration of a plate. The former enhances the perceived friction coefficient and the latter reduces it. This paper will highlight the independence of the two effects on the physical and perceptual point of view to confirm the increased range of sensation and stimulation that can be supplied by the two coupled techniques to the users. Firstly, a tribometric analysis of the induced lateral force on the finger by the two coupled effects will be presented, then a study on the dynamic of the two effects will be reported. In the end, a psychophysical experiment on the perception of the two coupled techniques will be shown.