PhD Thesis

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« Conception, fabrication and characterization of an haptic plate based on piezoelectric micro-actuators ».

Author: F. Bernard
Advisor: S. Basrour
President of jury: B. Lemaire-Semail
thesis reviewer(s): A. Giani, E. Defaÿ,
These de Doctorat Université Grenoble Alpes
Speciality: Electronique, électrotechnique, automatique
Defense: June 10 2016
ISBN: 978-2-11-129213-0


Haptic rendering systems, or textural recreated systems, are nowaday in constant expension and represent the next challenge for the mobile devices. One of the promising solution is based on the friction reduction generated by ultrasonic waves. The aim of this PhD is to develop an haptic rendering solution taking into account the issues of integration into mobile devices in terms of power consumption. More precisely, a solution based on piezoelectric thin films deposited onto a smartphone-sized transparent plate is proposed. Understanding the tactile perception phenomenons, the physical specifications are established in order to obtain an haptic stimulator. A theoretical model based on the Lamb wave reflections determined the vibration modes corresponding to the specifications for a constrain-free 5-inch smartphone size plate. The plate is put into vibration by Aluminum Nitrite thin-film piezoelectric transducers. Processed on one side of the plate, their dimension and position have been optimized thanks to finite element simulations. The final tactile prototype is designed allowing a 4-inch clear centrale space for positioning a futur LCD screen. After this design, the prototype is fabricated with cleanroom processes. The device is then electrically and mechanically characterized. The minimum power necessary to put in vibration the plate is determined, with the minimum specified vibration amplitude. The electronic for the actuation is optimized in order to reduce the power consumption of the system. Transducers, used as sensors, are characterized in order to create a feedback loop. A user case is finally studied to compensate the influence of the finger.