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Development of real-time ARM-based control system for autonomous platform Genesis
Hrvoje Pučak, 2021, magistrsko delo

Opis: Against the backdrop of technological advancement, machine learning and artificial intelligence, autonomous vehicles are also developing rapidly. In order for an autonomous vehicle to function properly, it is essential that the main system is provided lots of information about the vehicle, such as speed, orientation or battery state. Likewise, the system must control some actuators, such as drive motors and steering system. The specific objective of this thesis is to create an ARM-based module that will be a part of the Genesis II autonomous vehicle platform. The module is intended to accurately measure vehicle speed, estimate orientation and location, monitor the batteries, control drive motors and steering. The PCB layout of the module was developed by using Altium Designer, while the firmware was written in C programming language and by utilizing RTOS. Measurements were also performed to determine the accuracy of speed measurement process and to determine the accuracy of orientation and location estimations.
Ključne besede: ARM, autonomous vehicle, RTOS, Jetson TX2, magnetoresistive sensor, Genesis
Objavljeno: 02.06.2021; Ogledov: 85; Prenosov: 15
.pdf Celotno besedilo (1,83 MB)

Design of an Embedded Position Sensor with Sub-mm Accuracy
Matej Nogić, 2019, magistrsko delo

Opis: This master’s thesis presents the development of a machine-vision based localization unit developed at Robert Bosch GmbH, Corporate Sector Research and Advance Engineering in Renningen, Germany. The localization unit was developed primarily for position detection purposes with three degrees of freedom in highly versatile manufacturing systems but has an immense potential to be used anywhere where a precise, low-cost localization method on a two-dimensional surface is required. The complete product development cycle was carried out, from the components selection, schematic and optical system design, to the development of machine vision algorithms, four-layer Printed Circuit Board design and evaluation using an industrial robot. Thanks to the use of a patented two-dimensional code pattern, the localization unit can cover a surface area of 49 km2. The size and speed optimized, self-developed machine-vision algorithms running on a Cortex-M7 microcontroller allow achieving an accuracy of 100 µm and 60 Hz refresh rate.
Ključne besede: localization, machine-vision, code pattern, image sensor, embedded system
Objavljeno: 14.01.2020; Ogledov: 349; Prenosov: 0

High safety pillars stability control using EL beam displacement sensors in Lipica II quarry
Jože Kortnik, Sunny Nwaubani, Andrej Kos, 2014, izvirni znanstveni članek

Opis: In underground Lipica II. quarry for the excavation of natural stone, a modified room-and-pillar mining method is used, that is adjusted to the conditions of the site. In order to support and ensure the stability of underground chambers high safety pillars (HSP) are used. These pillars are made of surrounding stone and therefore intersected by discontinuities. The discontinuities represent high risk to the stability of underground facilities and workmen below/ itself. To ensure their safety the stress and strain parameters in height safety pillars are continuously monitored using two vibrating wire (WV) stressmeters inside the high safety pillars and two EL (Electronic level) beam sensors on the surface of the high safety pillar VS3. In the time period October 2010/June 2012 absolute max. measured deviation with EL beam sensors were D1=0.9 mm and D2=1.1 mm, which does not compromise the stability of the high safety pillar VS3. This paper presents the procedures of wedges deformation monitoring in safety pillars with EL beam sensors in the Lipica II underground natural stone quarry.
Ključne besede: beam sensor, high saftey pillar, monitoring, natural stone, room and pillar mining method
Objavljeno: 14.06.2018; Ogledov: 325; Prenosov: 30
.pdf Celotno besedilo (491,51 KB)
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A wearable device and system for movement and biometric data acquisition for sports applications
Marko Kos, Iztok Kramberger, 2017, izvirni znanstveni članek

Opis: This paper presents a miniature wearable device and a system for detecting and recording the movement and biometric information of a user during sport activities. The wearable device is designed to be worn on a wrist and can monitor skin temperature and pulse rate. Furthermore, it can monitor arm movement and detect gestures using inertial measurement unit. The device can be used for various professional and amateur sport applications and for health monitoring. Because of its small size and minimum weight, it is especially appropriate for swing-based sports like tennis or golf, where any additional weight on the arms would most likely disturb the player and have some influence on the player’s performance. Basic signal processing is performed directly on the wearable device but for more complex signal analysis, the data can be uploaded via the Internet to a cloud service, where it can be processed by a dedicated application. The device is powered by a lightweight miniature LiPo battery and has about 6 h of autonomy at maximum performance.
Ključne besede: biometric data acquisition, inertial sensing, movement detection, pulse rate, sensor fusion, wearable
Objavljeno: 03.08.2017; Ogledov: 645; Prenosov: 313
.pdf Celotno besedilo (8,88 MB)
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Intra-minute cloud passing forecasting based on a low cost iot sensor - a solution for smoothing the output power of PV power plants
Primož Sukič, Gorazd Štumberger, 2017, izvirni znanstveni članek

Opis: Clouds moving at a high speed in front of the Sun can cause step changes in the output power of photovoltaic (PV) power plants, which can lead to voltage fluctuations and stability problems in the connected electricity networks. These effects can be reduced effectively by proper short-term cloud passing forecasting and suitable PV power plant output power control. This paper proposes a low-cost Internet of Things (IoT)-based solution for intra-minute cloud passing forecasting. The hardware consists of a Raspberry PI Model B 3 with a WiFi connection and an OmniVision OV5647 sensor with a mounted wide-angle lens, a circular polarizing (CPL) filter and a natural density (ND) filter. The completely new algorithm for cloud passing forecasting uses the green and blue colors in the photo to determine the position of the Sun, to recognize the clouds, and to predict their movement. The image processing is performed in several stages, considering selectively only a small part of the photo relevant to the movement of the clouds in the vicinity of the Sun in the next minute. The proposed algorithm is compact, fast and suitable for implementation on low cost processors with low computation power. The speed of the cloud parts closest to the Sun is used to predict when the clouds will cover the Sun. WiFi communication is used to transmit this data to the PV power plant control system in order to decrease the output power slowly and smoothly.
Ključne besede: photovoltaic power plant, cloud passing forecasting, algorithm, sensor, Raspberry Pi, camera, wide-angle lens, optical filters, internet of things
Objavljeno: 20.07.2017; Ogledov: 1365; Prenosov: 325
.pdf Celotno besedilo (8,15 MB)
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Finite element modelling of a field-sensed magnetic suspended system for accurate proximity measurement based on a sensor fusion algorithm with Unscented Kalman Filter
Amor Chowdhury, Andrej Sarjaš, 2016, izvirni znanstveni članek

Opis: The presented paper describes accurate distance measurement for a field-sensed magnetic suspension system. The proximity measurement is based on a Hall effect sensor. The proximity sensor is installed directly on the lower surface of the electro-magnet, which means that it is very sensitive to external magnetic influences and disturbances. External disturbances interfere with the information signal and reduce the usability and reliability of the proximity measurements and, consequently, the whole application operation. A sensor fusion algorithm is deployed for the aforementioned reasons. The sensor fusion algorithm is based on the Unscented Kalman Filter, where a nonlinear dynamic model was derived with the Finite Element Modelling approach. The advantage of such modelling is a more accurate dynamic model parameter estimation, especially in the case when the real structure, materials and dimensions of the real-time application are known. The novelty of the paper is the design of a compact electro-magnetic actuator with a built-in low cost proximity sensor for accurate proximity measurement of the magnetic object. The paper successively presents a modelling procedure with the finite element method, design and parameter settings of a sensor fusion algorithm with Unscented Kalman Filter and, finally, the implementation procedure and results of real-time operation.
Ključne besede: accurate proximity measurement, sensor fusion algorithm, Unscented Kalman Filter, finite element modelling
Objavljeno: 22.06.2017; Ogledov: 749; Prenosov: 273
.pdf Celotno besedilo (9,23 MB)
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An EMI filter selection method based on spectrum of digital periodic signal
Marko Podberšič, Vojko Matko, Matjaž Šegula, 2006, izvirni znanstveni članek

Opis: This paper describes a new method for the selection of an appropriate signal lineElectromagnetic Interference (EMI) filter. To date, EMI filter selection has been based on the measurement of the radiation of the entire device. The new selection method based on the signal’s Fast Fourier Transform (FFT) measurement has proved to be efficient. The EMIfilter is optimized separately for each line. The method described in this paper involving aCentral Processor Unit (CPU) module demonstrates that the proposed FFT-based selection method is better than the radiation-based one. The radiation level in the frequency range 30MHz to 1 GHz is lower for approximate 2 – 6 dBμV/m.
Ključne besede: EMC, EMI filters, electrically long trace, typical frequency, sensor
Objavljeno: 22.06.2017; Ogledov: 485; Prenosov: 284
.pdf Celotno besedilo (189,00 KB)
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Uroš Pešović, 2016, doktorska disertacija

Opis: Data transmission sent through wireless channel is usually affected by background noise, multipath fading and interference which cause data errors. Influence of such disturbances is the most commonly expressed in a form of error probability statistics. Effects of these disturbances on IEEE 802.15.4 wireless transmissions are previously studied, except influence of co-channel interference (CCI) which originates from collision between IEEE 802.15.4 devices which perform simultaneous radio transmission. Our thesis puts forward the assumption that it is possible to derive more accurate analytical error probability model for higher data level error probability parameters without the idealization of PN spreading sequences. Additionally, thesis is that is possible to derive an accurate analytical error probability model in the case of CCI influenced by background noise by consideration of constellation diagram. IEEE 802.15.4 standard uses CSMA/CA (Carrier Sense Multiple Access with Collision Detection) channel access mechanism to prevent collisions between devices, but this mechanism doesn't provide protection from hidden node problem which is primary source of co-channel interference. Using Monte Carlo simulations we determined frequency of hidden node collisions, which shown that co-channel interference frequently occur in parts of the network with high traffic load. Some prior works in this field tend to idealize these non-ideal spreading sequences in order to simplify calculations for error probability parameters. Our doctor thesis presents analytical model of data level error probability parameters (symbol, bit and packet) for IEEE 802.15.4, which uses original non-ideal spreading sequences without their idealization. Proposed error probability model consists of mutually dependent chip, symbol, bit and packet error probability models. Derived error probability models are linked together, so each of error probability parameters can be determined using error probability parameter from the previous stage. Error probability model for IEEE 802.15.4 wireless communication could be used in network simulation tools in order to accurately simulate energy efficient medium access protocols in realistic scenarios. Presented theoretical results are tested by independent numerical simulation of IEEE 802.15.4 transmission according to Monte Carlo method. Simulation results shows that derived models for error probability parameters were matched by two simulation scenarios in background noise, for multipath fading and co-channel interface, respectively Furthermore, the accuracy of derived mathematical models was tested in real-world experiment using IEEE 802.15.4 compliant wireless transceivers for creating co-channel interference. Packets were received by software defined radio platform, which enabled realization of coherent receiver in which all error probability statistics could be collected. The results of the experiment show consistency with proposed analytical error probability models, but some deviations are caused by poor preamble synchronization under low SNR (Signal to Noise Ratio) value. The thesis was proved with Monte Carlo simulations of the physical level of the IEEE 802.15.4 communication and experimental measurements on a real physical communication system.
Ključne besede: IEEE 802.15.4 standard; error probability model; co-channel interference; Rician fading channel; additive white Gaussian noise; wireless transmission, wireless sensor networks, numerical simulations, software defined radio
Objavljeno: 14.10.2016; Ogledov: 1424; Prenosov: 79
.pdf Celotno besedilo (8,20 MB)

High-precision hysteresis sensing of the quartz crystal inductance-to-frequency converter
Vojko Matko, Miro Milanovič, 2016, izvirni znanstveni članek

Opis: A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter hysteresis, as well as the temperature compensation of the quartz crystal and any other circuit element. Also used is the programmable timing control device that allows the selection of different oscillating frequencies. In the proposed programmable method two different inductances connected in series to the quartz crystal are switched in a short time sequence, compensating the crystal’s natural temperature characteristics (in the temperature range between 0 and 50 °C). The procedure allows for the measurement of the converter hysteresis at various values of capacitance connected in parallel with the quartz crystal for the converter sensitivity setting at selected inductance. It, furthermore, enables the measurement of hysteresis at various values of inductance at selected parallel capacitance (sensitivity) connected to the quartz crystal. The article shows that the proposed hysteresis measurement of the converter, which converts the inductance in the range between 95 and 100 μH to a frequency in the range between 1 and 200 kHz, has only 7 × 10−13 frequency instability (during the temperature change between 0 and 50 °C) with a maximum 1 × 10−11 hysteresis frequency difference.
Ključne besede: inductance-to-frequency converter, hysteresis, automated measurement, sensor switching method, inductance, quartz crystal, temperature compensation
Objavljeno: 30.06.2016; Ogledov: 1214; Prenosov: 351
.pdf Celotno besedilo (3,93 MB)
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O kontaktni leči Sensor Triggerfish
Christoph Faschinger, Eva Faschinger, Sarah Krainz, Georg Mossböck, 2012, pregledni znanstveni članek

Opis: Namen prispevka je prikazati novo napravo, senzorsko kontaktno lečo Triggerfish, za stalno merjenje intraokularnega pritiska, dosedanje izkušnje in oceniti možnost njene uporabe. Prikazane so do sedaj objavljene raziskave na to temo. Naprava se dobro prenaša, je varna, preiskava se lahko ponovi. Do sedaj je še premalo podatkov, da bi jo lahko uporabljali že v vsakodnevni praksi pri zdravljenju glavkoma. Potrebne bodo še dodatne raziskave.
Ključne besede: intraocular pressure, sensor contact lens, safety, tolerability, reproducibility, validity
Objavljeno: 30.12.2015; Ogledov: 568; Prenosov: 25
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