Search results for "asynchronous"

Innovative Observers for Induction Motor Control

In this thesis the problem of designing observers and controllers for induction motors has been studied and thoroughly discussed using tools from the nonlinear system theory, both for analysis and control purposes. Useful techniques have been used to identify the machine parameters off-line. In the Introduction was dealt the design a control system for a drive of asynchronous machines that uses a voltage source inverter to generate the currents and voltages which carry the drive by making use of an observer of the state rotor variables. The used control algorithms is the \textit{field oriented control} (FOC). The model of the asynchronous induction motor is described starting from the mecha…

3D Map Computation from Historical Stereo Photographs of Florence

2018

The analysis of early photographic sources is fundamental for documenting and understanding the evolution of a city so rich in history and art as Florence. Indeed, by the 1860s several photographers used to work in town, and their images (often obtained through stereoscopic set-ups) can help us to reconstruct Florence in 3D as it was by the time of the Italian unification. The first and most delicate part of such reconstruction process is the computation of disparity maps from the historical stereo pairs. This is a very challenging task for fully-automatic computer vision algorithms, since XIX century photographs are affected by several problems—ranging from superficial damages to asynchron…

Asynchronously switched control of discrete impulsive switched systems with time delays

2013

This paper is concerned with the stabilization problem for a class of uncertain discrete impulsive switched delay systems under asynchronous switching. The so-called asynchronous switching means that the switches between the candidate controllers and system modes are asynchronous. By using the average dwell time (ADT) approach, sufficient conditions for the existence of an asynchronously switched controller is derived such that the resulting closed-loop system is exponentially stable. The desired controller gains and the admissible switching signals are obtained in terms of a set of matrix inequalities. A numerical example is given to illustrate the effectiveness of the proposed method.

A simple timestamping data acquisition system for ToF-ERDA

2015

A new data acquisition system, ToF-DAQ, has been developed for a ToF-ERDA telescope and other ToF-E and ToF-ToF measurement systems. ToF-DAQ combines an analogue electronics front-end to asynchronous time stamped data acquisition by means of a FPGA device. Coincidences are sought solely in software based on the timestamps. Timestamping offers more options for data analysis as coincidence events can be built also in offline analysis. The system utilises a National Instruments R-series FPGA device and a Windows PC as a host computer. Both the FPGA code and the host software were developed using the National Instruments LabVIEW graphical programming environment. Up to eight NIM ADCs can be han…

El aprendizaje a saltos mediante el uso de equipos de radio definida por software para la docencia en el grado en ingeniería electrónica de telecomun…

2021

[EN] How to design communications systems and its foundations depends on various factors such as the accessibility to learning resources, the academic environment and the audience itself. This article reports how the introduction of learning methodologies based on project based learning (PBL), practical devices and asynchronous working has modified the perception of the students about their learning aptitudes. The combination of traditional and offline sessions, with the PBL methodology to perform practical communications systems demonstrations based on professional SDR devices by group of students is presented and analysed in this article. The quantified outcome of their academic involveme…

Practical Implementation of a Synchronous PWM Strategy for Low Switching Frequency FOC of im Drives with ATSAM3X8E Microcontroller

2021

This paper presents a practical implementation of synchronous PWM modulation algorithm for an induction motor field oriented control powered by a DC/AC inverter and implemented on a low-cost microcontroller, the ATSAM3X8E. In particular, a simple algorithm, capable to calculate automatically an optimized set of frequency modulation indexes will be presented. Hysteresis bands are also introduced in the algorithm in order to avoid multiple changeovers during modulation index transitions. Experimental tests and their results will be shown and discussed, highlighting the benefits of the present algorithm, such as reduction of current harmonic content, reduction of current ripple and, consequent…

Visual spike-based convolution processing with a Cellular Automata architecture

2010

this paper presents a first approach for implementations which fuse the Address-Event-Representation (AER) processing with the Cellular Automata using FPGA and AER-tools. This new strategy applies spike-based convolution filters inspired by Cellular Automata for AER vision processing. Spike-based systems are neuro-inspired circuits implementations traditionally used for sensory systems or sensor signal processing. AER is a neuromorphic communication protocol for transferring asynchronous events between VLSI spike-based chips. These neuro-inspired implementations allow developing complex, multilayer, multichip neuromorphic systems and have been used to design sensor chips, such as retinas an…

AER Filtering Using GLIDER: VHDL Cellular Automata Description

2008

Cellular Automata (CA) is a bio-inspired processing model for problem solving, initially proposed by Von Neumann. This approach modularizes the processing by dividing the solution into synchronous cells that change their states at the same time in order to get the solution. The communication between them is crucial to achieve the correct solution. On the other hand, the Address-Event-Representation (AER) is a neuromorphic communication protocol for transferring asynchronous events between VLSI chips. These neuro-inspired implementations have been used to design sensor chips (retina, cochleas), processing chips (convolutions, filters) and learning chips, which makes it possible to develop co…

Link scheduling in sensor networks for asymmetric average consensus

2012

Wireless Sensor Networks constitute a recent technology where the nodes cooperate to obtain, in a totally distributed way, certain function of the sensed data. One example is the average consensus algorithm, which allows every node to converge to the global average. However, this algorithm presents two major drawbacks in practice. The first one is that instantaneous symmetric links are required, which are hard to ensure in practice because of the presence of wireless interferences. The second one is that all the nodes are required to communicate with all of their local neighbors in every iteration, which can lead to an unbounded delay. In order to solve these issues, we propose a novel link…

Alternative Energy Policy for Mitigating the Asynchrony of the Wind-Power Industry’s Supply Chain in Brazil

2018

High dependency on hydroelectricity has revealed drawbacks in the security of power supplies as a consequence of the climate variability in South America. Under these conditions, Brazil is starting to consider alternative renewable sources for energy production, seeking to avoid periods of scarcity while also promoting clean technologies in its electricity market. Since 2004, wind power has shown a significant rise in terms of installed capacity in this country. Despite increases in wind-power units, Brazil suffers from delays in setting up its transmission infrastructure, which affects the performance of the wind-power supply chain. This chapter presents a simulation model that helps asses…