A New Miniaturised Multi-Axis Force/Torque Sensors Based on Optoelectronic Technology and Simply-Supported Beam

This paper presents a methodology for the development of a multi-axis force/torque sensor based on optoelectronic technology. The advantages of using this sensing principle are the low manufacturing costs, the simple fabrication, and the immunity to electrical noise. The force/ torque sensor makes use of six optical sensors: each sensor measures the displacement of a reflective surface that moves integrally with a simply-supported beam. The proposed mechanical structure allows for a variety of shapes on the mechanical structure to be easily adaptable to many robot applications. In this paper, we present a five-axis force/torque sensor based on this optoelectronic principle. To measure force/torque components, two identical three-DoF force/torque sensor structures (comprised of three beams) are mounted on top of each other. Photo sensors and mirrors are fixed inside the structure to measure the six beam deflections. In this paper, we describe the sensor structure, design, fabrication, calibration, and verify our sensor development methodology

Dependence of the Impact Response of Polyvinylidene Fluoride Sensors on Their Supporting Materials’ Elasticity

Polyvinylidene fluoride (PVDF) is popular sensing material because of its unique piezoelectric characteristics. In this work an impact sensor was prepared from a sandwiched structure PVDF film, and the related detection circuits were presented. The dependence of the PVDF sensors’ response on the elasticity of the supporting materials was examined and discussed. Here two response indexes were discussed, which were the peak-to-peak voltage (Vpp) and the recovery time. Firstly, falling impact experiments were executed on desk-supported PVDF sensors (100 mm PVDF film) using free falls of different weights from different heights. Then the same shock experiments were repeated on the same sensor, but changing the backstops to a sponge and rubber, respectively. On the desk, the values of Vpp were bigger than when the other two backstops were used; but the changes of the impact energy could not be reflected by the PVDF sensor when it was supported by a hard material. It was found that the biggest sensitivity of the voltage response (about 96.62 V/J) was obtained by the sponge-supported sensor; for the same sensor, when it was supported by rubber, the slope was 82.26 V/J. Moreover, the recovery time for the desk-supported sensor was almost constant, varying from 0.15 to 0.18 s, while for the same sensor supported by sponge or rubber, its recovery time changed with the shifting of the impact energy in the range of 0.02~0.36 s, but no pattern could be found in the recovery-time characteristics

Characterization of new piezoelectric materials for sensing applications

This research is conducted in order to characterize a new material for its use in pressure sensors. The material to analyze is the PVDF, a semicrystalline polymer source with excellent physical and electrical properties which is emerging as a good substitute for other piezoelectric materials used today in sensors and actuators for various applications. For this purpose a pressure sensor is created in a metal flexible beam in which a force that will deform the material longitudinally is going to be exhorted. A strain gauge with the objective of monitoring the mechanical strain applied on the piezoelectric system and the response of the material will also be installed. The obtained results show, on the one hand, the importance of the molecular structure of the material as this only generates electricity in a particular molecular phase and, on the other hand, the results highlight the good response to the applied stress, reaching in some cases a voltage generation of 3 volts, making the electrical response of PVDF one of the highest compared to other responses coming from piezoelectric ceramic materials such as PZT.Esta investigación se realiza con el objetivo de caracterizar un nuevo material para su aplicación en sensores de presión. El material que vamos a analizar es el PVDF, un polímero de origen semicristalino con excelentes propiedades físicas y eléctricas que lo perfilan como un buen sustituto de otros materiales piezoeléctricos que se utilizan hoy en día en sensores y actuadores para diversas aplicaciones. Para ello se crea un sensor de presión en una viga flexible metálica donde después se ejercerá una fuerza que deformará longitudinalmente el material y unas galgas extensiométricas que sirven para monitorizar la deformación mecánica ejercida en el sistema y la respuesta piezoeléctrica del material. Los resultados obtenidos muestran, por una parte, la importancia de la estructura molecular del material pues éste solo genera respuesta eléctrica en una de sus fases y, por otra, resaltan la buena respuesta ante la deformación aplicada, llegando a generar en algunos casos un voltaje de hasta 3V convirtiendo la respuesta eléctrica del PVDF en una de las mayores en comparación con otras respuestas de materiales piezoeléctricos de origen cerámico como el PZT.Ingeniería Electrónica Industrial y Automátic