Individual information

Friction reduction using ultrasonic longitudinal surface vibration can modify the user perception of the touched surface and induce the perception of textured materials. In the current paper, the mechanisms of friction reduction using longitudinal vibration are analyzed at different finger exploration velocities and directions over a plate. The development of a non-Coulombic adhesion theory based on experimental results is evaluated as a possible explanation for friction reduction with vibrations that are non-collinear with the finger displacement. Comparison with experimental data shows that the model adequately describes the reduction in friction, although it is less accurate for low finger velocities and depends on motion direction.

The design and closed loop control of a device able to produce both longitudinal mode and transverse mode vibration, at about the same resonance frequency (60 kHz) are presented in this article. The structure uses an array of piezo-ceramics. A dynamic analysis is performed on the obtained modes, and their dynamic lumped parameters are identified. A closed loop control is performed to maintain the desired vibration amplitude in the presence of a finger. Longitudinal and transverse motion cartographies show that the objective of achieving and controlling pure modes independently has been achieved. Using this device, tribological, psychophysical and energetic analyses are carried out. The analyses show that in terms of friction measurements and perception, both modes produce equivalent results. In terms of active power losses, an advantage of the longitudinal mode over the transverse mode is observed due to the interaction with the finger.

When a finger touches an ultrasonic vibrating plate, a non-sinusoidal contact force is produced. This force is called acoustic finger force. In a setup where closed-loop control is performed on the vibration amplitude, a component of the acoustic finger force can be measured at the fundamental vibration frequency of the plate. This calculation is obtained from the measurement of the variation of the controller voltage between the no-load case and when a finger is present. This calculation is made for a group of twelve participants. From these results a PCA (Principal Component Analysis) model is created. This model permits estimation of the acoustic finger force response of a participant at any vibration amplitude, based on a one or two point measurement. Finally, a linear relation between the PCA coefficients and the friction reduction is proposed. The objective of this relation would be to ultimately provide the means to create an amplitude reference calibration based on the desired friction reduction level, and thus be able to produce a standardized tactile feedback for each user, despite the biomechanical differences in finger pad properties between subjects.

When the finger interacts with a surface where a purely lateral ultrasonic vibration occurs, a vibration attenuation is produced. An added force is therefore needed in order to maintain the vibration amplitude in closed loop control. In this article we explore whether the friction reduction in lateral ultrasonic surface haptic devices may be predicted using static measurements of this additional force.

Friction attenuation using ultrasonic lateral surface haptic devices (ULSHD) can modify the user perception of the touched surface and induce the perception of textured materials. In the current paper, the mechanisms of friction attenuation using lateral vibration are analyzed at different finger exploration velocities and directions over a plate. A development of a non-Coulombic friction function based on experimental results is proposed and evaluated.

In this paper, we propose a new device in order to produce normal and lateral ultrasonic vibrations in a plate, using an array of piezoelectric ceramics. This setup serves to continue the comparative analysis between the two vibration modes for tactile feedback rendering, by including an energetic characterization. With the help of a tribological analysis, this study will help to examine the energy performance of each vibration mode in terms of active power consumption against friction contrast (which is linked to perception). Using a simplified second order plate model, the energetic results are analyzed. The results show a better energy efficiency for the lateral vibration for low exploration speeds. The tribological analysis helps as well to evaluate the effect of frequency increase in terms of friction reduction vs. vibration amplitude for both vibration modes

In this paper, a psychophysical experiment is designed and setup to perform the comparison between lateral and normal ultrasonic vibration for friction modulation on haptic devices at the same vibration amplitudes. Thanks to a simple analytical modelling relying on mechanical contact, the results obtained are explained. A parametric analysis of this comparison is then performed.

In this paper, we present a method to observe the fundamental of the acoustical finger force for the case of a friction reduction based haptic interface. The capability of the method to be achieved on-line, in a small micro-controller is established. We show a correlation between this measurement and the friction when sliding the finger. A model that predicts the friction coefficient and the friction contrast is laid down; it gives consistent output for 10 participants out of 12 having different biomechanical parameters of the skin.

This article presents the development of an algorithm which can be used at standstill and low speed for sensorless control of a five-phase Permanent Manget Synchronous Machines (PMSM) with non-salient poles. The estimation method is based on the machine’s torque. Two different strategies are investigated for the proposed method. The first one uses the torque measurement and the second one uses the estimated torque from the measured currents. Results for the implementation of both strategies are presented and analysed, together with possible improvements to explore.

A rotor position estimation for low speed and standstill applications in multiphase PMSMs with non-salient poles is presented in this paper. For this purpose, a comprehensive state of the art was performed. Then, an estimation method was proposed based on existing methods for surface three-phase PMSMs, and is finally adapted to a five-phase machine. Experimental results are illustrated and analysed.

La technologie haptique offre aux utilisateurs un moyen unique d'interagir avec les mondes virtuels en permettant le transfert direct d'informations entre les interfaces et l'être humain par le biais du sens du toucher. Les dispositifs haptiques de surface utilisent différentes techniques pour moduler la friction afin de simuler la texture. Dans le cas des surfaces haptiques à ultrasons, on utilise des céramiques piézoélectriques qui, alimentées par une tension alternative sinusoïdale, provoquent un mouvement à la surface du dispositif. Ce mouvement est transmis et amplifié par le matériau, à sa fréquence de résonance.Les modes vibratoires transversaux sont couramment utilisés dans la technologie haptique des surfaces ultrasoniques. Ce travail évalue la possibilité d'utiliser les vibrations longitudinales comme une alternative technologique pour produire un retour haptique dans les dispositifs à ultrasons. Pour cela, des comparaisons sont effectuées sur les deux familles de modes, à partir d’un dispositif dédié à la fois d’un point de vue performances énergétiques et qualité des stimuli perçus. L'action et la perception de l'homme dans ce contexte sont très importantes. Malheureusement, en raison de la complexité des phénomènes de friction, la réponse sensorielle est différente d'un utilisateur à l'autre, avec le même stimulus haptique. Pour cette raison, il est intéressant d'explorer l'humain dans la boucle de simulation tactile. Dans ce but, une première tentative de développer le concept de "Human-in-the-Loop" en haptique de surface est présentée dans cette thèse, en utilisant le formalisme EMR (Energetic Macroscopic Representation) développé au sein de l'équipe de contrôle du L2EP et déjà couramment appliqué au HIL (Hardware in the Loop).