1,721,253 research outputs found
Non invasive laser measurement techniques in on-line diagnostics of house-hold appliances (MEDEA project)
No full textPressure Sensor Matrix for Indirect Measurement of Grip and Push Forces Exerted on a Handle
No full textTo date, a large part of workers is exposed to vibrations (23% in Europe) which can negatively impact on their health. This work discusses the importance of measuring grip and push forces in the context of hand-arm vibration tests, bearing in mind the state-of-art of current standards. It proposes a method for indirect measurement of coupling forces using a matrix of polymeric pressure capacitive sensors and discusses the model used for defining these quantities. The matrix of pressure sensors is wrapped around the tool handle and the acting forces, exchanged with the handle, are derived from the pressure values measured by the matrix. Calibration is presented and the effect of curvature is discussed. The work continues with the experimental validation of the model proposed for push force measurements carried out through lifting tests using known masses with a cylindrical handle. An experimental correction coefficient is defined in correlation to the type of grip. The method for measuring the push force, thus corrected, is assessed by means of push force tests on an instrumented handle. Finally the experimental data are analysed in order to assess the uncertainty of the proposed method for measuring the push force, highlighting the contribution of the different sources of uncertainty. The proposed measurement method allows to measure the push and the grip force (known influencing quantities for the measurement of the hand-arm vibration) during tool test and without modifying the handles
La definizione e la misura delle azioni di presa e di spinta esercitate su di una impugnatura
No full textLaser Doppler vibrometry based on self-mixing effect
No full textIn this paper, a simple, compact and low cost laser Doppler vibrometer is presented. It is simply composed of a laser diode (9 mm in diameter, 2 g of weight, emitting at 825 nm) and by a two-lens optical system designed to focus the laser radiation on the vibrating target. This sensor can measure target velocity. The working principle is based on the self-mixing effect that occurs in a semiconductor laser diode when the emitted radiation is back reflected toward the cavity and then re-introduced inside. The target velocity is calculated measuring the frequency of the peak of the spectrum of the signal generated by a photodiode mounted on the back facet of the laser diode. In this article, the design and the realisation of the vibrometer is reported. The self-mixing vibrometer has been calibrated in the range 0–300 mm/s, using a rotating disk covered with white paper. The effect of the angle of measurement and target distance are reported. Finally, the sensor has been compared with a commercial laser Doppler vibrometer using a vibrating surface as a target
La misura della pressione plantare nella pratica clinica: pubblicata la nuova norma tecnica CEI 62-236.
No full textThe use of devices for the measurement of the plantar pressure, such as pressure sensor matrices, is today increasingly widespread in the clinical practice. These measurement instruments are medical devices and require a specific reference standard for conformity assessment. The Italian Electrotechnical Committee CEI (CT-62) has published the new Technical Norm CEI 62-236:2015-01: “Plantar pressure measurement devices (PPMD): measurement performances”. The standard aims at improving the quality of the PPMD measurements and of their clinical efficacy. With respect to the development of suitable instrumental setups, the standard provides, beyond the building and functional requirements, useful instructions for the setting up of the appropriate test instrumentation
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