Finite Element Modelling and Simulation of a Capacitive Ultrasonic Sensor

Santos Escribano, Jaime de los (2018). Finite Element Modelling and Simulation of a Capacitive Ultrasonic Sensor. Proyecto Fin de Carrera / Trabajo Fin de Grado, E.T.S.I. Industriales (UPM).


Title: Finite Element Modelling and Simulation of a Capacitive Ultrasonic Sensor
  • Santos Escribano, Jaime de los
  • Oliver Ramírez, Jesús Angel
Item Type: Final Project
Degree: Grado en Ingeniería en Tecnologías Industriales
Date: November 2018
Freetext Keywords: CUT: Capacitive Ultrasonic Transducer FEM: Finite Element Modelling Comsol: Simulation Software Senscomp: Brand of the studied Sensor
Faculty: E.T.S.I. Industriales (UPM)
Department: Automática, Ingeniería Eléctrica y Electrónica e Informática Industrial
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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The Series 600 Senscomp Ultrasonic Sensor has existed now for more than 50 years, and it was already implemented in products almost 40 years ago, more precisely in the PolaroidTM 600, for its autofocus system. Nowadays, it still is one of the sensors that come in mind when facing the task of developing ultrasonic ranging systems, although mainly the piezoelectric transducers are market-leading. The objective of this research is trying to understand how this device is built, with the idea of achieving an optimization of the same. This study focuses on a model of the sensor as a validation for the apparent operating mode and a point of departure for future variations and improvement of the sensor. The key parameters for the validation of the simulation are the characteristics given in the products data sheet. The methodology employed consists basically of three steps: disassembling the sensor, modelling it with the help of a simulation software, COMSOL, and comparing the results with the real data in order to validate or falsify the thesis and assumptions. The first one was naturally accompanied by various measurements of the decisive magnitudes of the device and research on the used materials. It is important to highlight that as a consequence of this step, the sensor was necessarily damaged, leaving it useless. After that a familiarization with COMSOL took place, which later enabled the construction of the model. Having determined the operating mode of the device, the implied physical phenomena and the precise function of each element, the model was built. At this point, two different version of the same had to be developed due to the different possibilities given by the software, which were not a priori better than the other. This process consisted mainly of the creation of the geometry, reducing it to the essential elements, the physical characterization of the components and their interaction and the creation of an adequate mesh. This last concept is an essential part of the Finite Element Method, which is a pillar of this thesis. The last step was the comparison of the resulted plots with the given: the typical beam pattern at 50 kHz and the transmit frequency response. In general, the results of the simulation validate one of the models and dismiss the possibility of using the other. The program chosen for the representation of the comparison was Matlab. Although showing some sensitivity defects in the beam pattern, with up to 10 dB errors, the broad outlines of the model correspond with the reality. This means it is not yet a finished model, but it is close to be one, specially considering that the imperfections derive presumably from a lack of mechanical damping. All in all, it can be considered as a starting point for the development of an optimized or alternative capacitive ultrasonic transducer.

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Item ID: 53770
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Deposited by: Biblioteca ETSI Industriales
Deposited on: 30 Jan 2019 07:43
Last Modified: 29 Mar 2019 23:30
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