| | SLO | ENG | Piškotki in zasebnost

Večja pisava | Manjša pisava

Iskanje po katalogu digitalne knjižnice Pomoč

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


1 - 10 / 19
Na začetekNa prejšnjo stran12Na naslednjo stranNa konec
1.
Electrohydraulic pressure control by a self-adjusting proportional derivative controller
Darko Lovrec, Friedrich Faber, 2006, izvirni znanstveni članek

Opis: The main characteristic of an electrohydraulic pump control system is the presence of an electrical signal path. It requires at least one sensor for the controlled value (in this case pressure), delivering feedback to be compared with the electrical or numerical reference in the controller. The additonal expense penalty for the sensor and the valve is offset by the advantage of flexibility in the structure and parameters of the controller in comparison to hydraulic - mechanical concepts. Thus, the transfer response can be adapted to demands, even in the operational state. Sophisticated control structures can be implemented easily in the form of computer or microcontroller programs. The layout of electrohydraulic pressure control discussed in this study includes the presented loading unit. The variable pump is designed to act together with a proportional valve having two metering edges. It is less expensive compared to the design with a synchronizing cylinder and four metering edges. However, only inferior static and dynamic performance can be expected. Hydraulic energy is supplied to the control valve directly from the output port of the pump - with the advantage of simple assembly, as there are no additional components required - but with the drawback that there is influence on the control loop`s properties at every change in the disturbance value or reference. The aim of the study presented in this paper is a more efficient and simple concept compared to other known methods for pressure control of the above mentioned pump including the dynamics of the distribution network, and also the characteristics of the hydraulic load with special focus on improvements in steady state and dynamic behaviour.
Ključne besede: automatic control engineering, electrohydraulic systems, pressure control, self-adjusting proportional controller
Objavljeno: 31.05.2012; Ogledov: 1096; Prenosov: 57
URL Povezava na celotno besedilo

2.
Adaptive self-learning controller design for feedrate maximization of machining process
Franc Čuš, Uroš Župerl, 2007, izvirni znanstveni članek

Opis: An adaptive control system is built which controlling the cutting force and maintaining constant roughness of the surface being milled by digital adaptation of cutting parameters. The paper discusses the use of combining the methods of neural networks, fuzzy logic and PSO evolutionary strategy (Particle Swarm Optimization) in modeling and adaptively controlling the process of end milling. An overall approach of hybrid modeling of cutting process (ANfis-system), used for working out the CNC milling simulator has been prepared. The basic control design is based on the control scheme (UNKS) consisting of two neural identificators of the process dynamics and primary regulator. Experiments have confirmed efficiency of the adaptive control system, which is reflected in improved surface quality and decreased tool wear.
Ključne besede: end milling, adaptive force control, artificial intelligence, optimisation, adaptive control systems
Objavljeno: 31.05.2012; Ogledov: 925; Prenosov: 23
URL Povezava na celotno besedilo

3.
Pressure control in hydraulic systems with variable or constant pumps?
Darko Lovrec, Samo Ulaga, 2007, izvirni znanstveni članek

Opis: The paper deals with electrohydraulic supply systems with variable (adjustable( supply pressures. Two control concepts are used in practice: the pressure control concept using a variable pump and constant speed of the driving electric motor as the commonly used concept, and the pressure control concept with a constant pump and a speed-controlled electric motor as the alternative concept. The typical features and the applicability of both conceps, as well as their dynamic responses are studied in this work.
Ključne besede: automatic control engineering, hydraulic systems, pressure control, constant pumps
Objavljeno: 31.05.2012; Ogledov: 1080; Prenosov: 0

4.
Fuzzy logic based quality monitoring in short-circuit gas metal arc welding
Marjan Golob, Arpad Köveš, 2007, izvirni znanstveni članek

Opis: Conventional methods, e.g. destructive and non-destructive testing methods, are expensive and time-consuming; therefore, possibilities of online and automated quality control of a welding process during welding as such are investigated. The paper deals with the possibilities of application of fuzzy logic to the analysis of weld quality, particularly assessment of the weld surface condition by means of measurable electric signals emitted during welding. A simple fuzzy inference system was realised which could relatively efficiently assess the weld quality on the basis of time variations of the welding voltage and short-circuit time in a certain time window.
Ključne besede: fuzzy systems, fuzzy logic, gas metal arc welding, GMAW, quality monitoring, statistical analysis, quality control, weld quality
Objavljeno: 31.05.2012; Ogledov: 1016; Prenosov: 69
URL Povezava na celotno besedilo

5.
Improving integrity of embedded computers in control
Matjaž Colnarič, Domen Verber, Wolfgang A. Halang, 2003, pregledni znanstveni članek

Opis: This paper gives an overview of a holistic project dealing with the consistent design of embedded control systems falling into the first level of safety integrity requirements (SIL l) (IEC, 1998). It shows how existing methods can be adapted and reasonably employed, whenever possible, without having to resort to new innovations. Firstly, the hardware issues are dealt with and extensively elaborated, particularly the peripheral interfaces with integrated processing capabilities. Secondly, the proven correct real-time operating system executing on its own dedicated processor is briefly addressed, and finally, programming issues including descriptions of the specific programming language, time bounded handling of exceptions, and how to deal with temporal overload.
Ključne besede: safety critical embedded systems, embedded systems, fault tolerant control systems, peripheral interfaces, exception handling, overload
Objavljeno: 01.06.2012; Ogledov: 853; Prenosov: 69
URL Povezava na celotno besedilo

6.
OPC-driven data exchange between MATLAB and PLC-controlled system
Stojan Peršin, Boris Tovornik, Nenad Muškinja, 2003, izvirni znanstveni članek

Opis: Many manufacturing, and mechatronics systems, are controlled by PLCs and SCADAsystems. These systems provide very limited possibilities for research, optimisation, testing and simulation. The main advantage of this proposed solution, which uses OPC, is an integration of the numerical, computational and graphical strengths of MATLAB with the robustness of industrial systems. The experimental setup, the processing of the data and the results are presented with particular emphasis on student use in a laboratory environment but the techniques employed in the experiments will likely to be seen by the students in their subsequent employment after completion of their college careers.
Ključne besede: mechatronics, industrial automation, industrial systems, MATLAB, SCADA systems, process control
Objavljeno: 01.06.2012; Ogledov: 959; Prenosov: 21
URL Povezava na celotno besedilo

7.
A PID servo control system experiment conducted remotely via Internet
R. M. Parkin, C. A. Czarnecki, Riko Šafarič, D. W. Calkin, 2002, izvirni znanstveni članek

Opis: The principles of robotics and control are widely taught in engineering subjects, however a common problem concerns the limited availability of expensive equipment with which students can work with, in order to acquire valuable practical "hands on" experience. The MuMaTE virtual robotics and control project on the World Wide Web (www) was launched to evaluate the suitability of virtual learning environments, the Internet, and multimedia technologies within an engineering-based flexible learning program. Students using networked computers can access this facility to study a wide variety of on-line course material and perform a series of interactive experiments with real world laboratory hardware. This paper presents an on-line experiment, which enabled users to successfully control and observe the response of a commercial position servo system. The development of the project web server, interface electronics and control software is also discussed.
Ključne besede: automatic control, control, control systems, virtual learning, distance learning, servo system
Objavljeno: 01.06.2012; Ogledov: 997; Prenosov: 50
URL Povezava na celotno besedilo

8.
9.
10.
Effects of small-world connectivity on noise-induced temporal and spatial order in neural media
Matjaž Perc, 2006, izvirni znanstveni članek

Opis: We present an overview of possible effects of small-world connectivity on noise-induced temporal and spatial order in a two-dimensional network of excitable neural media with FitzHugh-Nagumo local dynamics. Small-world networks are characterized by a given fraction of so-called long-range couplings or shortcut links that connect distant units of the system, while all other units are coupled in a diffusive-like manner. Interestingly, already a small fraction of these long-range couplings can have wide-ranging effects on the temporal as well as spatial noise-induced dynamics of the system. Here we present two main effects. First, we show that the temporal order, characterized by the autocorrelation of a firing-rate function, can be greatly enhanced by the introduction of small-world connectivity, whereby the effect increases with the increasing fraction of introduced shortcut links. Second, we show that the introduction of long-range couplings induces disorderof otherwise ordered, spiral-wave-like, noise-induced patterns that can be observed by exclusive diffusive connectivity of spatial units. Thereby, already a small fraction of shortcut links is sufficient to destroy coherent pattern formation in the media. Although the two results seem contradictive, we provide an explanation considering the inherent scale-free nature of small-world networks, which on one hand, facilitates signal transduction and thus temporal order in the system, whilst on the other hand, disrupts the internal spatial scale of the media thereby hindering the existence of coherent wave-like patterns. Additionally, the importance of spatially versus temporally ordered neural network functioning is discussed.
Ključne besede: physics, complex systems, dynamical systems, noise, chaos, chaotic systems, chaos control, resonance
Objavljeno: 07.06.2012; Ogledov: 1074; Prenosov: 51
URL Povezava na celotno besedilo

Iskanje izvedeno v 0.17 sek.
Na vrh
Logotipi partnerjev Univerza v Mariboru Univerza v Ljubljani Univerza na Primorskem Univerza v Novi Gorici