Showing papers by "Pedro Silva Girao published in 2001"
TL;DR: In this paper, a brief overview of some existing solutions is presented and two systems for axial linear displacement measurement based on light intensity detection are introduced. The systems have redundancy and were designed with the purpose of achieving identification and automatic correction of errors arising from inadvertent angular variations between the sensor and the light beam positions.
Abstract: The present work is a contribution to the field of linear displacement measurements by optical means. For that purpose, a brief overview of some existing solutions is presented and two systems for axial linear displacement measurement based on light intensity detection are introduced. The systems have redundancy and were designed with the purpose of achieving identification and automatic correction of errors arising from inadvertent angular variations between the sensor and the light beam positions.
68 citations
05 Nov 2001
TL;DR: Simulation and experimental results are used to confirm the theoretical expectations of the proposed solution for nonlinear transducer interfacing and provide an automatic variable range selection and continuous auto-calibration capabilities that can be used to correct offset and gain errors.
Abstract: This paper proposes a linearization technique based on a pulse width modulated (PWM) analog-to-digital (A/D) converter. The hardware and software associated with the converter are specially tailored to linearize transducer characteristics by varying the duty cycle of the PWM signal in each of the input range sub-intervals (IRS) that are considered for a given application. The proposed solution can also provide an automatic variable range selection and continuous auto-calibration capabilities that can be used to correct offset and gain errors. Simulation and experimental results are used to confirm the theoretical expectations of the proposed solution for nonlinear transducer interfacing.
13 citations
15 Jul 2001
TL;DR: The application of artificial neural network data processing in measuring systems is reviewed and neural network types better suited for different kind of applications in that domain are briefly described.
Abstract: The application of artificial neural network (ANN) data processing in measuring systems is reviewed. Neural network types better suited for different kind of applications in that domain are briefly described, with identification of the particular characteristics that make each type suitable for each kind of application. Several aspects concerning optimization and the virtual and hardware implementation of ANN are also examined.
10 citations
15 Jul 2001
TL;DR: Several artificial neural network architectures are designed, tested and implemented in the microcontroller to perform the CO digital readout task with compensation of errors due to the most important influence quantities.
Abstract: Reports an application of neural networks to the measurement of carbon monoxide in air. The measurement system uses a tin film sensor. To increase system performances and capabilities, a microcontroller and complex processing are added to the sensor. Several artificial neural network architectures are designed, tested and implemented in the microcontroller to perform the CO digital readout task with compensation of errors due to the most important influence quantities. Special attention is paid to the implementation of multilayer perceptrons and radial basis functions and to the selection of the smallest neural network topology for an imposed modeling error.
6 citations
05 Nov 2001
TL;DR: A displacement measuring system based on one optical emitter, two optical sensors and on a smart structure used for sensor data processing around the PIC16F877 8-bit microcontroller that powers the sensors, acquires data from the sensors and performs the intelligent processing based on a neural algorithm.
Abstract: The paper presents a displacement measuring system based on one optical emitter (laser diode), two optical sensors and on a smart structure used for sensor data processing. The system is designed around the PIC16F877 8-bit microcontroller that powers the sensors, acquires data from the sensors and performs the intelligent processing based on a neural algorithm. Communication between the smart sensor and a personal computer (PC) is possible using a RS232 interface. A practical approach concerning the laser diode behavior, the on-line correction of the tilt angle influences, and the microcontroller implementation of the neural processing algorithm are also presented.
1 citations