An acoustic multi-touch sensing method using amplitude disturbed ultrasonic wave diffraction patterns

This paper proposes an acoustic multi-touch tactile sensing method. The proposed method is based on an amplitude disturbed ultrasonic wave diffraction pattern. An A0 Lamb wave transmitted in a thin finite copper plate is processed to provide tactile information, for one or two fingers. A touch event is localized by identifying the diffraction signals among a database of diffracted Lamb wave references. Statistic models are used to improve the localization reliability. An artificial silicone finger is used in the calibration procedure. This touch interface is evaluated as a 2-touch interface

Acoustic Wave Approach for Multi-Touch Tactile Sensing

International audienceIn this communication, we present a high resolution tactile plate that can localize one or two contact fingers. The localization principle is based on Lamb wave absorption. Fingers' contact will generate absorption signals while Lamb waves are propagating in a thin finite copper plate. These signals can be related to the contact positions and can be calibrated before the use of tactile plate. Fingers' contact positions are calculated by finding the closest calibration signal to the measured signal. Positions are carried out in less than 10 ms with a spatial resolution of 2 mm for one finger localization. Multi-points localization by this technology is developed and a two-point case is initialized and tested. Several optimization methods are also presented in this paper, as the double validation check which could improve the accuracy of single-point localization from 94.63% to 99.5%

An acoustic multi-touch sensing method using amplitude disturbed ultrasonic wave diffraction patterns

This paper proposes an acoustic multi-touch tactile sensing method. The proposed method is based on an amplitude disturbed ultrasonic wave diffraction pattern. An A0 Lamb wave transmitted in a thin finite copper plate is processed to provide tactile information, for one or two fingers. A touch event is localized by identifying the diffraction signals among a database of diffracted Lamb wave references. Statistic models are used to improve the localization reliability. An artificial silicone finger is used in the calibration procedure. This touch interface is evaluated as a 2-touch interface.International audienceThis paper proposes an acoustic multi-touch tactile sensing method. The proposed method is based on an amplitude disturbed ultrasonic wave diffraction pattern. An A0 Lamb wave transmitted in a thin finite copper plate is processed to provide tactile information, for one or two fingers. A touch event is localized by identifying the diffraction signals among a database of diffracted Lamb wave references. Statistic models are used to improve the localization reliability. An artificial silicone finger is used in the calibration procedure. This touch interface is evaluated as a 2-touch interface

Tactile objects based on an amplitude disturbed diffraction pattern method

Tactile sensing is becoming widely used in human-computer interfaces. Recent advances in acoustic approaches demonstrated the possibilities to transform ordinary solid objects into interactive interfaces. This letter proposes a static finger contact localization process using an amplitude disturbed diffraction pattern method. The localization method is based on the following physical phenomenon: a finger contact modifies the energy distribution of acoustic wave in a solid; these variations depend on the wave frequency and the contact position. The presented method first consists of exciting the object with an acoustic signal with plural frequency components. In a second step, a measured acoustic signal is compared with prerecorded values to deduce the contact position. This position is then used for human-machine interaction (e.g., finger tracking on computer screen). The selection of excitation signals is discussed and a frequency choice criterion based on contrast value is proposed. Tests on a sandwich plate (liquid crystal display screen) prove the simplicity and easiness to apply the process in various solids

Lamb-wave (X, Y) giant tap screen panel with built-in microphone and loudspeaker

International audienceThis paper presents a passive (X, Y) giant tap screen panel (GTP). Based on the time difference of arrival principle (TDOA), the device localizes low-energy impacts of around 1 mJ generated by fingernail taps. Selective detection of A0 Lamb waves generated in the upper frequency spectrum, around 100 kHz, makes it possible to detect light to strong impacts with equal resolution or precision, close to 1 cm and 2 mm, respectively, for a 10-mm-thick and 1-m$^2$ glass plate. Additionally, with glass, symmetrical beveling of the edges is used to create a tsunami effect that reduces the minimum impacting speed for light taps by a factor of three. Response time is less than 1 ms. Maximum panel size is of the order of 10 m$^2$. A rugged integrated flat design with embedded transducers in an electrically shielding frame features waterproof and sticker/ tag proof operation. Sophisticated electronics with floating amplification maintains the panel at its maximum possible sensitivity according to the surrounding noise. Amplification and filtering turns the panel into a microphone and loudspeaker featuring 50 mV/Pa as a microphone and up to 80 dB$_{lin}$ between 500 Hz and 8 kHz as a loudspeaker

Moderately reverberant learning ultrasonic pinch panel

International audienceTactile sensing is widely used in human-computer interfaces. However, mechanical integration of touch technologies is often perceived as difficult by engineers because it often limits the freedom of style or form factor requested by designers. Recent work in active ultrasonic touch technologies has made it possible to transform thin glass plates, metallic sheets, or plastic shells into interactive surfaces. The method is based on a learning process of touch-induced, amplitude-disturbed diffraction patterns. This paper proposes, first, an evolution in the design with multiple dipole transducers that improves touch sensitivity or maximum panel size by a factor of ten, and improves robustness and usability in moderately reverberant panels, and second, defines a set of acoustic variables in the signal processing for the evaluation of sensitivity and radiating features. For proof of concept purposes, the design and process are applied to 3.2- and 6-mm-thick glass plates with variable damping conditions. Transducers are bonded to only one short side of the rectangular substrates. Measurements show that the highly sensitive free lateral sides are perfectly adapted for pinch-touch and pinch-slide interactions. The advantage of relative versus absolute touch disturbance measurement is discussed, together with tolerance to abutting contaminants

250 DPI at 1000 Hz acquisition rate S0_0 lamb wave digitizing pen

International audience—This paper presents an active stylus (X,Y) flat digitizing tablet (AST). The tablet features an acquisition rateof 1000 pts/s with 0.1 mm resolution. The cordless stylus incorporates a 1-mA low-power pulse generator. Precision is limitedby diffraction to about ±0.3 mm on a 57 × 57 mm region of a 71 × 71 × 1 mm digitizing plate. Selective generation anddetection of the S$_0$ Lamb mode with a precessing tip is the key feature of this tablet. We first highlight the ultrasonic propagation inside the stylus tip and stability of Lamb wave generation when the stylus is inclined, rotated, and slid. Then, modeling of the limitations imposed by diffraction of a 1-MHz burst S$_0$ plane Lamb wave packet is carried out. The model takes into account high-order zero crossing detection as well as reflections and shear horizontal (SH) conversions of the S$_0$ Lamb mode at free edges of a glass plate. Reflection and transmission through an isotropic PZT bar are also calculated. Finally, localization precision by time difference of arrival (TDOA) is calculated and experimentally verified near the borders of the plate, taking into account the angular sensitivity of the precessing tip

New probe design for hardware characterization by ElectroMagnetic Fault Injection

International audienceElectroMagnetic Fault Injection requires two main devices, a pulse generator and an electromagnetic (EM) injection probe. To improve security characterizations, inductive probes need to be optimized as regards the pulse waveform and field distribution. The improvement of these parameters leads to greater electromotive forces generated in the integrated circuits, which reinforces the efficiency of the attacks by fault injections. This paper presents a complete model of the electromagnetic field induced at the target surface according to Biot and Savart's law. This work defines the relevant design parameters of the new probes that are used for hardware characterization of the target components. These new probes reduce the voltage fault threshold required to disturb the execution of a program in the target. This paper also presents results related to the optimization of spatial resolution and inductive power at the target circuit surface. Understanding these phenomena then helps to implement countermeasures and best secure the strategies of the key IC components

Procédé tactile à diffraction ultrasonore

Cette thèse est une contribution au développement d'un procédé tactile acoustique basé sur la perturbation des ondes de Lamb, permettant de détecter un toucher simple ou des touchers multiples sur des objets minces de forme quelconque. Après avoir étudié la propagation des modes de Lamb dans les objets minces par exemple les plaques de cuivre d'épaisseur 450 m, nous avons observé, que l'énergie des ondes de Lamb antisymétriques était essentiellement due à la composante normale de déplacement et qu'il était aisé de perturber un mode de flexion par un toucher surfacique réalisé avec le doigt ou ponctuel avec la pointe d'un stylo, tandis que dans le cas d'un mode symétrique, l'énergie était essentiellement distribuée sur la composante de déplacement tangentielle et en conséquence plus difficilement perturbée par une interaction tactile. Nous avons en conséquence exploité le toucher sur une plaque mince perturbant le rayonnement d'une onde acoustique dans l'objet et réalisé en pratique une mesure de la perturbation d'un signal de diffraction des ondes de Lamb en un ou deux points récepteurs d'une plaque. Ainsi, une méthode de localisation basée sur la diffraction des ondes a été proposée, pour obtenir une interface tactile compacte, performante et faible coût. Cette méthode nommée méthode de la Figure de Diffraction Perturbée en Amplitude (FDPA) peut rendre une surface tactile avec une résolution spatiale de l'ordre du millimètre et un temps de réponse inférieur à 10 ms. Deux méthodes d'optimisation sont proposées pour obtenir un taux de localisation correcte proche de 100%. Le procédé tactile et les méthodes d'optimisation présentés dans cette thèse ont été testés sur plusieurs types d'objets, réalisés dans des matériaux différents et sous différentes formes géométriques. Ces réalisations ont montré des performances satisfaisantes en termes d'encombrement, de consommation et de fiabilité de localisation pour des touchers simples et multiples.This thesis is a contribution to the development of an acoustic tactile process based on the disturbance of Lamb waves making it possible to detect a simple or multitouch interaction on thin objects of various shapes. After studying the propagation of Lamb modes in thin objects such as a copper plate 450 m thick, we show that the energy of antisymmetric Lamb modes is essentially related to the normal component of displacement and that it is easy to disturb bending waves either with a stylus based punctual touch or finger based surfacic touch, whereas in the case of a symmetric Lamb mode, energy is essentially due to the tangential mechanical component of displacement, therefore more difficult to disturb with a touch of the finger. Consequently, we have exploited the touch disturbed radiation of an acoustic bending wave and measured the disturbance of diffracted Lamb waves at one or two receiving points of the plate. Thus, a method based on the diffraction of Lamb waves has been proposed for the development of a compact, efficient and low cost tactile interface. This method named Amplitude Disturbed Diffraction Pattern (ADDP) method can be used to produce a tactile surface that can achieve a spatial resolution of the order of one millimeter and a response time of 10 ms. Two optimization methods are proposed to obtain near 100% correct localization. The proposed process and optimization methods have been tested on several kinds of objects made with different materials and forms. These realizations have shown satisfying performances in terms of form factor, consumption and reliability of localization of simple or plural contact points.PARIS-Arts et Métiers (751132303) / SudocSudocFranceF

Temperature dependency comparison of ultrasonic wave propagation between injected and sintered thermoplastics

International audienceActive touch localization based on a learning process of touch-disturbed broadband bending wave propagation in thin objects is used to transform any 3D surface into a multi-touch interface. Fast prototyping permits easy manufacturing of various 3D shapes that can be as quickly transformed into touch interfaces. The drawback is their weak mechanical stability with temperature. This paper details the temperature behavior differences between a sintered plastic such as polyamide polymer of type PA12 and raw injected Acrylonitrile-Butadiene-Styrene composite polymer (ABS), in particular how their physical parameters such as Young's modulus and Poisson's ratio are affected by temperature. Correlatively, longitudinal and transversal waves within injected and sintered plastics are investigated across a commercial temperature range of 10 °C to 70 °C. The internal grain structure in plastics obtained by laser sintering of powder makes these materials prone to stronger damping and clear non-linear temperature dependency of the shear wave velocity compared with injected plastics