Matteo Bonaiuti

Design of a high-performance optical system for angular position measurement: optical and electronic strategies for uncertainty reduction

A high performance optical system to reduce measuring errors and uncertainty in angular encoders is presented. We propose a novel reading optical head, which exploits a lens system to improve the speed of the beam crossing the photodetector and a quadrant photodiode to perform a zero-crossover acquisition of the timing information.

Application of the BJT detector for simple, low-cost, and low-power alpha-particle detection systems

We present a simple, low-cost, and low-power alpha-particle detection system for environmental radioactivity monitoring. The system exploits a previuosly-developed high- resistivity-silicon detector with internal amplification capability based on the bipolar-transistor (BJT) effect and readout electronics based on commercial ICs. Two-dimensional numerical device simulations are adopted to assess the feasibility of the BJT detector as an alpha-particle detector that can be operated, without losing its internal signal amplification capability, with floating base and low collector voltages, so that device technology can be kept simple, very small DC power consumption can be achieved, and a single 5-V power-supply voltage can be used for readout electronics and detector biasing. The charge amplification accomplished by the BJT detector allows a single, commercial chip to be adopted, to perform charge preamplification and 20-bit A/D conversion. The digital output is sent to a low-cost microcontroller that can be periodically interrogated through the IR port. The cost of the readout electronics is in the order of 60

An Inertial/RFID Based Localization Method for Autonomous Lawnmowers

and it can operate with standard Li-ion battery for about 60 hours.

Alpha-particle detection based on the BJT detector and simple, IC-based readout electronics

Abstract Robotic lawnmowers currently available in the market cover their assigned area using a random reflection navigation strategy. While this strategy has been widely accepted for autonomous vacuum cleaning systems, it poses quality problems in outdoor applications since a randomic crossing of the garden can lead to an uneven mowing. In this paper we propose a localization algorithm based on a modified Constrained Kalman Filter that allows to implement an efficient navigation strategy and to increase the quality of service of the mower. This method properly merges data coming from an Inertial Measurement Unit (IMU) and from an RFID (Radio-Frequency IDentification) antenna with information given by the Hall sensors of the wheels of the robot. The proposed algorithm has been verified first by simulation, and then with experiments by building a prototype lawnmower robot.

Radon alpha-ray detector based on a high-resistivity-silicon BJT and a low-cost readout electronics

In this paper we propose a portable instrument for alpha-particle detection based on a previously-developed BJT detector and a simple, IC-based readout electronics. Experimental tests of the BJT detector and readout electronics are reported. Numerical simulations are adopted to predict the performance enhancement achievable with optimized BJT detectors.

A 2.4-GHz wireless alpha-ray sensor for remote monitoring and spectroscopy

Radon dosimetry yields valuable information about radioactive health risks in closed environments. Indeed, World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) have recently classified radon as a human carcinogen and have demonstrated a correlation between environmental radon concentration and lung cancer risk. Dose measurements are traditionally based on laboratory analysis of alpha-ray traces in ionization chambers exposed to environmental air. In this paper we propose a portable instrument for real-time radon alpha-ray detection based on a previously-developed high-resistivity-silicon BJT sensor and a low-cost, IC-based readout electronics.

Study of GaN HEMTs electrical degradation by means of numerical simulations

Wireless alpha-ray device has been designed, realized and tested in operation. The first prototype is a battery-supplied system with a compact package and wireless communication capability. One of the more attractive features is its ability to operate in a star network (single point-to-multipoint). The sensor records the arrival time of the alpha particles and the spectrum of the produced charge; it transmits this information in regular time intervals or upon request to the base station. The overall system has a compact package suitable for remote alpha-ray spectroscopy.

Image processing algorithms for ocular fundus reflectometry

In this paper, we investigate the effects of dc stress on GaN high-electron mobility transistors (HEMTs) by means of numerical simulations. Following stress tests showing a degradation of static characteristics (dc), the formation of an electron trap in the AlGaN barrier layer was related to the observed degradation according to the results obtained from numerical simulations carried out by introducing a trapping region underneath the gate edge. The worsening of the device dc performance is evaluated by changing the extension of the degraded region and the trap concentration while studying the variation of parameters like the saturated drain current IDSS, the output conductance gO, and the device transconductance gM. An increase in the trap concentration induces a worsening of any of the abovementioned parameters; an increase in the extension of the degraded region induces a degradation of IDSS and gM, but can reduce gO.

A system for functional imaging of the ocular fundus

Ocular fundus reflectometry is a technique aimed at the in-vivo measurement of the reflectance of the tissues of the ocular fundus. Studies have demonstrated a correlation between optical and physiological properties of such tissues in humans and the existence of a control mechanism, called neuro-vascular coupling (NC), which adjusts local blood perfusion to support vision-induced neural activity. We developed an instrument for functional imaging of the neural tissues of the ocular fundus based on reflectance measurements to study the NC. The images acquired with the instrument needed processing to work out reflectance time-courses. The algorithm exploited previously requires long computational time, provides poor discrimination of objects and need manual intervention. We have developed a fully automatic algorithm based on differential multiscale framework for the processing of the images of the ocular fundus with reduced computational time. This algorithm is reasonably efficient to determine relative translational displacement (translation and rotation) between the images and also to remove the geometric distortion. Simulation results performed on the fundus images show that differential multiscale framework based image registration reduces computational times up-to one fourth of the time required by the general purpose algorithm, and provides better alignment precision.

A PC-controlled nonincremental distance meter based on a comb-spectrum combined with a frequency-modulated continuous wave interferometer

Neurovascular coupling in the optic nerve is the physiological mechanism that adjusts the blood perfusion in the microcirculation of the optic nerve to support the neural activity induced by vision. The resulting variations in blood flow and thus in neural tissue oxygenation induce changes in the optical properties of the tissues. These variations can be detected optically as reflectivity changes in the neural tissues, i.e. the retina and optic nerve disk. To achieve a better understanding of the mechanisms underlying the neurovascular coupling, our study is aimed at the evaluation of reflectance changes of the optic nerve induced by visual stimulation. For this purpose, an ocular fundus reflectometer has been developed.