Aldo Baccigalupi

A measurement laboratory on geographic network for remote test experiments

A remote laboratory for teaching purposes in the field of measuring experiments was activated. Students can access automatic measuring setups and instruments via geographic network and directly carry out real experiments. With respect to current literature solutions, this has been realized on the basis of de-facto networking standards so that students are required to use only a simple commercial Web Internet browser. Moreover, a concurrence of more users on the same measuring setup is allowed. The remote laboratory concept allows measuring resources spread on different geographically remote sites to be utilized by a wide deal of students. In this way, a more complete educational proposal can be economically offered by several geographically remote laboratories specialized in different measuring fields.

A digital signal-processing instrument for impedance measurement

A digital signal processing (DSP)-based instrument for impedance measurement is proposed. It implements two measurement techniques: the first technique allows the tracking of a time varying impedance to be carried out, and the second assures that good accuracy is obtained in reasonable measurement times. Both the software and the hardware of a prototype model are described in detail. The measurement rates and accuracy are evaluated and compared with those obtained using a reference Digibridge for a wide range of impedance values.

A remote measurement laboratory for educational experiments

The paper deals with a Remote Laboratory (RemLab) based on a Web site for remote teaching of measurements. RemLab was specifically designed in order to provide a remote access to instrumentation by means of only a commercial Web browser. Students get hypertextual tutorials on measurement topics, use remote instrumentation, and download result files for further local processing. Beyond educational aims, RemLab allows experimental know-how in the measurement field as well as research experimental results to be effectively diffused and exploited. Software and hardware design solutions as well as experimental results of educational measurement features are discussed.

Ultrasonic time-of-flight estimation through unscented Kalman filter

This paper deals with distance or level measurements based on ultrasonic time-of-fight estimation. Moving from a past experience concerning the proposal of a method based on discrete extended Kalman filter (DEKF) to overcome some limitations of already available ultrasonic-based techniques, a new digital signal processing method capable of granting further improvements is presented. The method is based on the unscented Kalman filter (UKF), which is a new extension of the Kalman filter theory mandated to face some DEKF problems, mainly due to its inherent linearization approach. To this aim, UKF is applied to the acquired ultrasonic signal in order to estimate the returned echo envelope as well as to locate its onset more accurately. After describing key features and implementation issues of the new method, the results obtained in a number of tests on simulated and actual ultrasonic signals, which assess its reliability and effectiveness as well as advantages with respect to the previous one, are given.

Remote Didactic Laboratory “G. Savastano,” The Italian Experience for E-Learning at the Technical Universities in the Field of Electrical and Electronic Measurements: Overview on Didactic Experiments

The Remote Didactic Laboratory Laboratorio Didattico Remoto - LA.DI.RE. ldquoG. Savastanordquo is the e-learning measurement laboratory supported by the Italian Ministry of Education and University. It involves about 20 Italian universities and provides students of electric and electronic measurement courses with access to remote measurement laboratories delivering different didactic activities related to measurement experiments. In order to demonstrate the versatility for didactic use, the overview of some experiments is given. The didactic experiments summarized in this paper concern measurement characterization of instruments and communication systems, measurement devices for remote laboratories, basic electrical measurements, magnetic measurements, electromagnetic-interference measurements, and signal processing for measurement applications.

On a circuit theory approach to evaluate the stray capacitances of two coupled inductors

The authors provide a method for evaluating three lumped equivalent capacitances which take into account the physical effects of stray capacitances in two coupled inductors. Capacitance evaluation is performed in two steps. Initially, the resistance and leakage inductance of every winding and the core exciting equivalent impedance are evaluated by means of discrete parameter estimation. Then the three equivalent capacitances are evaluated by means of three simple mathematical expressions once the natural oscillation frequencies of the two coupled inductors in the experimental test are determined. The definitions and the mathematical theory underlying the method are outlined. The actual reponse of the two coupled inductors is compared with the response of the identified model and the test results show a good correlation between them.<<ETX>>

Field Programmable Analog Arrays for Conditioning Ultrasonic Sensors

This paper proposes the use of field programmable analog arrays (FPAAs) as adaptive conditioning blocks for ultrasonic sensors. The uncertainty achievable through this technique, in fact, results very sensitive to the measurement conditions, due to the attenuation affecting the echo during its propagation. Indeed, FPAAs emulate analog circuits whose characteristics have to be dynamically tuned according to different operating conditions. Actually, the signal provided by the ultrasonic sensor is properly processed in order to improve the overall measurement accuracy. In this paper, the prototype of a distance meter based on time-of-flight (TOF) measurement is presented in order to evidence the advantages gained by FPAA features in processing the sensor output to compensate echo attenuation and distortion versus target distance. The prototype working is supervised by a digital signal controller (DSC) whose tasks are: 1) driving the ultrasonic transducer; 2) performing the echo acquisition; 3) tuning on the fly the FPAA features; 4) evaluating the TOF; 5) measuring the target distance; and 6) delivering the final result to the end user. This paper is completed by the results achieved in a number of experimental tests allowing interesting considerations to be drawn. In particular, the experiments confirm the prototype reliability and effectiveness also with ultrasonic echoes characterized by very low signal-to-noise ratios.

Error compensation of A/D converters using neural networks

This paper describes a new technique for compensating errors in analog-to-digital converters (ADCs). It can be considered an improvement of the phase plane compensation technique: the idea is to exploit the generalization capabilities of Artificial Neural Networks (ANNs) to reduce the large number of experiments required. The ANN is built and set up in a simulation environment using an ADC behavioral model, whose errors can be fixed to known values. It is thus possible to simulate a set of ADCs with very different performances, thereby enabling the usefulness of the proposed approach to be investigated in very different working conditions. The results were analyzed by comparing the behaviour of uncompensated and compensated ADC outputs.

Remote Didactic Laboratory “G. Savastano,” The Italian Experience for E-Learning at the Technical Universities in the Field of Electrical and Electronic Measurement: Architecture and Optimization of the Communication Performance Based on Thin Client Technology

The Remote Didactic Laboratory Laboratorio Didattico Remoto -LA.DI.RE. “G. Savastano” is an e-learning measurement laboratory supported by the Italian Ministry of Education and University. It provides the students of electric and electronic measurement courses with access to remote measurement laboratories, delivering different didactic activities related to measurement experiments. The core of the software architecture is the integration of the Learning Management System (LMS) with the remotely accessible measurement laboratories through web services and thin client paradigm, providing a new approach to remote experiments on measurement instrumentation. The overview of this paper is on the different solutions concerning the thin client technology, and the solution implemented is described. This solution takes into account the delivered services to students and teachers and permits optimization of the communication performances. The results of the comparison among the performances of different implementations of the thin client paradigm highlight the advantages of the adopted solution. As a consequence, the description of the thin client protocol implemented, together with the presentation of the LMS and delivered services given in a previous paper, makes an exhaustive analysis of the software architecture of the LA.DI.RE. “G. Savastano.”

A digital-signal-processor-based measurement system for on-line fault detection

This paper deals with the design, construction, and setting up of a measurement apparatus, based on an architecture using two parallel digital signal processors (DSPs), for on-line fault detection in electric and electronic devices. In the proposed architecture, the first DSP monitors a device output on-line in order to detect faults, whereas the second DSP estimates and updates the system-model parameters in real-time in order to track their eventual drifts. The problems which arose when the proposed apparatus was applied to a single-phase inverter are discussed, and some of the experimental results obtained in fault and nonfault conditions are reported.