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Simulations of VoIP applications in INET framework
Sebastijan Horvatić, 2017, master's thesis

Abstract: This master's thesis describes the support for modelling Voice over Internet Protocol (VoIP) applications in the INET Framework. First, it briefly presents the VoIP technology and factors responsible for the VoIP quality of service. Next, the thesis moves on to discuss the OMNeT++ environment and the INET Framework, their installation and usage. Following this, it examines all of the INET packages and modules available for VoIP modelling, with all VoIP-related INET examples then shortly described and tested. By using INET, our own network and application models are created and simulated using different parameters. Comparisons of the simulation results are carried out and some of the best-found parameters for the VoIP communications are presented. At last, the calculation of jitter by using the obtained simulation results and Excel program is described, because jitter is not shown in the simulation results in INET.
Keywords: voice over internet protocol, performance analysis, simulation, real-time transport protocol, user datagram protocol
Published: 18.08.2017; Views: 711; Downloads: 88
.pdf Full text (3,86 MB)

Position control with parameter adaptation for a nano-robotic cell
Gregor Škorc, Jure Čas, Simon Brezovnik, Riko Šafarič, 2011, original scientific article

Abstract: This paper describes the development of a nano-assembly system, built up using linear piezo motors. The so-called nano-robotic cell is based on an X/Y manipulator, supported by three serving tables, movable within a Z axis, and aposition controlled using two different types of a bang-bang control methods. The presented application has been developed as a stand-alone application with the LabVIEW Real Time software package, a PCI-7356 servo controller card and a TMCM-090 stepper driver. Our experiments focused on two major problems present during the construction of nano-robotic assembly cells. The first one is a nonlinear characteristic of a linear piezo motor, which makes the use of classical control methods very limited. The second problem appears when a nano-robotic cell needs a bigger working space and at the same time, production demands that the manipulator moves more often over longer distances. In order to position in nano-resolution, the motors have to run at higher resolutions with smaller speeds. Therefore, long distance moves slow down the entire production process. Experiments on this system have shown that positioning within the nano-scale is possible, using a simple control method such as the bang-bang control method. Although positioning using this method is possible, certain limitations and weaknesses exists, making this simple method useless in nano-scale if higher speeds and longer move distances are needed. Certain changes in the basic control algorithm are proposed, which will ensure that the bangbang control method becomes useful within higher speeds and over longer distances. All recommendations are supported and backed- up by practical experimental results.
Keywords: nanorobotske celice, nanopozicioniranje, histerezni krmilnik, proizvodnja MEMS, realno-časovni LabView, nano-robot cells, nano-positioning, bang-bang controller, MEMS assembly, LAbVIEW, real time
Published: 10.07.2015; Views: 957; Downloads: 108
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Co-processor for microkernel OS services
Domen Verber, 2011, published scientific conference contribution

Keywords: operating systems, embedded systems, real time, task scheduling, FPGA
Published: 10.07.2015; Views: 632; Downloads: 80
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Implementation of hard real-time embedded control systems
Matjaž Colnarič, Domen Verber, Roman Gumzej, Wolfgang A. Halang, 1998, independent scientific component part or a chapter in a monograph

Abstract: Although the domain of hard real-time systems has been thoroughly elaborated in the academic sphere, embedded computer control systems - being an important in mechatronic design - are seldom dealt with consistemntly. Often, off-the-shelf computer systems are used, with no guarantee that they will be able to meet the requirements specified. In this paper, a design for embedded control systems is presented. particulary, the paper deals with the hardware architecture and design details, the operating sustem, and the high-level real-time language support. It is shown how estimates of process run-times necessary for schedulability analysis can be acquired on the basis of deterministic behavior of the hardware platform.
Keywords: kontrolni sistemi, realni čas, mikrokontrolerji, programski jeziki, embedded compuer control systems, hard real-time systems, microcontrollers, transputers, earliest-deadline-first scheduling, real-time programming languages
Published: 10.07.2015; Views: 694; Downloads: 83
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Real-time motor unit identification from high-density surface EMG
Vojko Glaser, Aleš Holobar, Damjan Zazula, 2013, original scientific article

Abstract: This study addresses online decomposition of high-density surface electromyograms (EMG) in real-time. The proposed method is based on previouslypublished Convolution Kernel Compensation (CKC) technique and sharesthe same decomposition paradigm, i.e. compensation of motor unit action potentials and direct identification of motor unit (MU) discharges. In contrast to previously published version of CKC, which operates in batch mode and requires ~ 10 s of EMG signal, the real-time implementation begins with batch processing of ~ 3 s of the EMG signal in the initialization stage and continues on with iterative updating of the estimators of MU discharges as blocks of new EMG samples become available. Its detailed comparison to previously validated batch version of CKC and asymptotically Bayesian optimal Linear Minimum Mean Square Error (LMMSE) estimator demonstrates high agreementin identified MU discharges among all three techniques. In the case of synthetic surface EMG with 20 dB signal-to-noise ratio, MU discharges were identified with average sensitivity of 98 %. In the case of experimental EMG, real-time CKC fully converged after initial 5 s of EMG recordings and real-time and batch CKC agreed on 90 % of MU discharges, on average. The real-time CKC identified slightly fewer MUs than its batch version (experimental EMG, 4 MUs versus 5 MUs identified by batch CKC, on average), but required only 0.6 s of processing time on regular personal computer for each second of multichannel surface EMG.
Keywords: discharge pattern, high-density EMG, surface EMG, motor unit, real time decomposition
Published: 25.05.2015; Views: 900; Downloads: 0

Specification PEARL constructs for embedded real-time systems co-design
Roman Gumzej, Matjaž Colnarič, 2002, original scientific article

Abstract: In the article a HW/SW co-design methodology is presented, which enables early reasoning about system integration as well as verification of the designs. Specification PEARL methodology is based on a specification language with the same name, whose ori-gins are in the standard Multiprocessor PEARL language. It has been enhanced by addi-tional components for asymmetrical multiprocessor systems design as well as by additional parameters for RTOS parameterisation and feasibility analysis. Timed State Transition Diagrams have been introduced for program/task modelling, supporting the PEARL pro-cess model. The resulting task models are easily translated to PEARL task prototypes. The methodology and its specification language components are being presented.
Keywords: embedded systems, real-time systems, co-design, modelling, PEARL
Published: 01.06.2012; Views: 1891; Downloads: 19
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A safety shell for UML-RT projects
Roman Gumzej, Wolfgang A. Halang, 2008, published scientific conference contribution

Abstract: A safety shell pattern was defined based on a reconfiguration management pattern, and inspired by the architectural specifications in Specification PEARL. It is meant to be used for real-time applications to be developed with UML-RT as described. The implementation of the safety shell features as defined by in [8], namely its timing and state guards as well as I/O protection and exception handling mechanisms, is explained. The pattern is parameterised by defining the properties of its components as well as by defining the mapping between software and hardware architectures. Initial and alternative execution scenarios as well as the method for switching between them are defined. The goal pursued with the safety shell is to obtain clearly specified operation scenarios with well defined transitions between them. To achieve safe and timely operation, the pattern must provide safety shell mechanisms for an application designed, i.e., enable its predictable deterministic and temporally predictable operation now and in the future.
Keywords: real-time systems, embedded systems, UML profiles, UML patterns, safety
Published: 31.05.2012; Views: 1224; Downloads: 150
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