1. Comparative Study of GPR Acquisition Methods for Shallow Buried Object DetectionPrimož Smogavec, Blaž Pongrac, Andrej Sarjaš, Venceslav Kafedziski, Nabojša Dončov, Dušan Gleich, 2024, original scientific article Abstract: This paper investigates the use of ground-penetrating radar (GPR) technology for detecting shallow buried objects, utilizing an air-coupled stepped frequency continuous wave (SFCW) radar system that operates within a 2 GHz bandwidth starting at 500 MHz. Different GPR data acquisition methods for air-coupled systems are compared, specifically down-looking, side-looking, and circular acquisition strategies, employing the back projection algorithm to provide focusing of the acquired GPR data. Experimental results showed that the GPR can penetrate up to 0.6 m below the surface in a down-looking mode. The developed radar and the back projection focusing algorithm were used to acquire data in the side-looking and circular mode, providing focused images with a resolution of 0.1 m and detecting subsurface objects up to 0.3 m below the surface. The proposed approach transforms B-scans of the GPR-based data into 2D images. The provided approach has significant potential for advancing shallow object detection capabilities by transforming hyperbola-based features into point-like features.
Keywords: GPR, UAV, SFCW radar, acquisition methods
Published in DKUM: 04.12.2024; Views: 0; Downloads: 5
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2. Avtonomna, GPS vodena robotska platformaGaj Krajnc, 2024, undergraduate thesis Abstract: V diplomskem delu je predstavljena predelava komercialne kosilnice v avtonomno vozilo. Predelavo je bila izvedena s pomočjo mikroračunalnika ter RTK GPS modula, ki omogoča natančno določanje lokacije vozila v realnem času. Avtonomna vožnja se izvaja s pomočjo ROS okolja, ki skrbi za korektno delovanje vseh komponent. V delu željeni cilji glede natančnosti niso bili doseženi, vendar je rezultat kljub temu zadovoljiv.
Keywords: GPS, RTK, ROS okolje, OpenMower, Raspberry Pi4
Published in DKUM: 19.09.2024; Views: 0; Downloads: 22
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3. Vodenje krožnega inverznega nihala z oddaljenim merilnim mestom : magistrsko deloUroš Stiplovšek, 2024, master's thesis Abstract: V magistrski nalogi je predstavljena regulacija vpete palice na sistem, ki se vrti okoli lastne osi, pri čemer je cilj, da je ta sistem sposoben postaviti palico v pokončno lego in jo tam za nekaj časa zadržati. Pri tem je palica vpeta na vrtljivo os sistema. Najprej smo vzpostavili komunikacijo med glavnim mikrokrmilnikom in računalnikom. Sledila je vzpostavitev povezave s pomočjo NRF modula med glavnim mikrokrmilnikom in mikrokrmilnikom, ki se je nahajal na sistemu. Po uspešni povezavi smo se lotili branja kota palice in kota vrtenja samega sistema. Nato smo načrtali tri regulatorje: PID, polinomsko sintezo in regulator v prostoru stanj. Pri slednjem smo dobili najboljši odziv, zato smo ga tudi uporabili pri končnem sistemu. S prilagajanjem parametrov in poskušanjem smo dosegli cilj naloge. Na koncu smo izdelali tiskano vezje in s tem izboljšali videz sistema.
Keywords: regulacija nihala, regulacijski sistemi, NRF komunikacija, komunikacija dveh mikrokrmilnikov, branje kota, regulacija v prostoru stanj.
Published in DKUM: 26.04.2024; Views: 278; Downloads: 63
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4. Cross-Hole GPR for Soil Moisture Estimation Using Deep LearningBlaž Pongrac, Dušan Gleich, Marko Malajner, Andrej Sarjaš, 2023, original scientific article Abstract: This paper presents the design of a high-voltage pulse-based radar and a supervised data processing method for soil moisture estimation. The goal of this research was to design a pulse-based radar to detect changes in soil moisture using a cross-hole approach. The pulse-based radar with three transmitting antennas was placed into a 12 m deep hole, and a receiver with three receive antennas was placed into a different hole separated by 100 m from the transmitter. The pulse generator was based on a Marx generator with an LC filter, and for the receiver, the high-frequency data acquisition card was used, which can acquire signals using 3 Gigabytes per second. Used borehole antennas were designed to operate in the wide frequency band to ensure signal propagation through the soil. A deep regression convolutional network is proposed in this paper to estimate volumetric soil moisture using time-sampled signals. A regression convolutional network is extended to three dimensions to model changes in wave propagation between the transmitted and received signals. The training dataset was acquired during the period of 73 days of acquisition between two boreholes separated by 100 m. The soil moisture measurements were acquired at three points 25 m apart to provide ground truth data. Additionally, water was poured into several specially prepared boreholes between transmitter and receiver antennas to acquire additional dataset for training, validation, and testing of convolutional neural networks. Experimental results showed that the proposed system is able to detect changes in the volumetric soil moisture using Tx and Rx antennas.
Keywords: ground penetrating radar, cross-hole, L-band, deep learning, convolutional neural network, soil moisture estimation
Published in DKUM: 03.04.2024; Views: 448; Downloads: 25
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5. Frequency range optimization for continuous wave Terahertz imagingBlaž Pongrac, Andrej Sarjaš, Dušan Gleich, original scientific article Abstract: S krajšimi valovnimi dolžinami kot mikrovalovi in večjo globino prodora v material kot infrardeča svetloba, valovi v TeraHertz-nem (THz) spektru ponujajo edinstvene možnosti testiranja materialov. THz tehnologija ponuja neinvazivna in nedestruktivna testiranja v obliki spektroskopije in slikanja. Najbolj uporabljeni sistemi za THz slikanje so sistemi spektroskopije v časovni domeni. Vendar sistemi spektroskopije frekvenčne domene ponujajo odlično frekvenčno ločljivost in so primerni za biomedicinske aplikacije. THz-no slikanje na podlagi spektroskopije v frekvenčnem prostoru je časovno kompleksno in ima pomanjkljivosti zaradi napak pri generiranju THz valov. V tem članku je predstavljen nov princip enodimenzionalnega zajemanja s THz valovi. Predlagana optimizacija frekvenčnega območja temelji na konvolucijski nevronski omreži. Predstavljena je frekvenčna optimizacija za določitev optimalnega frekvenčnega območja za zajem podatkov. Optimalno frekvenčno območje ali pasovna širina morata biti dovolj široka za učinkovito zaznavanje faze in morata biti na presečišču več spektralnih odtisov v opazovanem mediju. Presek spektralnih odtisov je ocenjen z uporabo predlaganega algoritma za optimizacijo frekvenčnega območja, ki temelji na konvolucijski nevronski mreži in algoritmu za občutljivost okluzije. Predlagani algoritem izbira samodejno najobčutljivejši frekvenčni pas THz spektra in omogoča zelo hitre zajeme za pregled in klasifikacijo objektov.
Keywords: terahertz, spectroscopy, imaging, convolutional neural network, occlusion sensitivity, optimization
Published in DKUM: 07.12.2023; Views: 421; Downloads: 23
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6. Event-triggered second-order sliding mode controller design and implementationAndrej Sarjaš, Dušan Gleich, 2023, original scientific article Abstract: The paper presents an event-triggered higher-order sliding mode controller design. The event-triggering technique is the alternative approach to real-time controller execution, unlike the classic time-triggering technique, which is not time-dependable and is governed by the triggering policy. The technique is suitable for system resource relaxation in case of computation burden or network usage mitigation. The paper describes the stability analysis of the super-twisted sliding mode controller based on input-to-state stability notation. The stability analysis introduces a triggering policy related directly to the ultimate boundness of the system states and preselected sliding variables. The controller time execution with the selected triggering condition prevents the exhibition of the Zeno phenomena, where the minimal inter-event time of the controller has a positive non-zero lower bound. The minimal value of the inter-event time is related directly to the controller parameters and triggering bound, the selection of which is given with the derived stability conditions regarding the designer’s objective. Preventing the fast nonlinear controller execution, especially close to the sliding manifold, also alleviates the chattering phenomena effectively, which is a primal drawback, and limits the usage of the controller on various systems. The method’s efficiency is verified with the hardware-in-the-loop system, where the dynamic and robustness of the triggering approach are compared to the standard time-triggered execution technique.
Keywords: event triggering, sliding mode control, super-twisted controller, chattering alleviation
Published in DKUM: 07.12.2023; Views: 370; Downloads: 19
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7. Samosprožilno mrežno vodenje z nelinearnim modelom na osnovi globokega učenja : magistrsko deloSebastjan Vogrinčič, 2023, master's thesis Abstract: Magistrska naloga opisuje modeliranje nelinearnih dinamičnih sistemov in implementacijo samosprožilnega dogodkovnega vodenja na sistemu zračne levitacije z namenom reševanja sodobnih problemov vodenja, kot je preobremenjenost omrežja. Najprej smo vzpostavili komunikacijo med sistemom in računalnikom z namenom priprave podatkov. Sledila je faza globokega učenja in validacija modela. Na koncu smo načrtali ustrezen algoritem, ki posodablja izhod regulatorja glede na predikcijo modela. Z magistrskim delom smo predvsem dokazali delovanje obravnavanega vodenja na hitrem nelinearnem in nestabilnem sistemu. Ugotovili smo, da je zanesljivost takega vodenja predvsem odvisna od natančnosti modela. Samosprožilno vodenje je lahko riskantno, zato je za industrijsko aplikacijo potrebno vpeljati dodatne varnostne mehanizme.
Keywords: samosprožilno vodenje, dogodkovno proženje, nelinearni model, globoko učenje, NARX.
Published in DKUM: 05.10.2023; Views: 298; Downloads: 52
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10. Vektorsko vodenje zračne potisne sile togo vpetega pogona : diplomsko deloUroš Kukovič, 2023, undergraduate thesis Abstract: Diplomsko delo obravnava vektorsko vodenje potiska zračnega ventilatorja, ki vpliva na naklon celotnega mehanizma. Vektorsko vodenje se doseže z nagibnim mehanizmom (ang. gimbal) in se uporablja v letalstvu s poudarkom na vojaških bojnih letalih za povečanje okretnosti letalskega plovila. Opisani koncepti se lahko uporabijo tudi kot podlaga za izvedbo vektorskega vodenja raketnega pogona. Diplomsko delo zavzema opis koncepta vektorskega vodenja s primeri 3D modeliranja mehanizma. Nazadnje obsega še sintezo zaprto-zančnega sistema in njegovo implementacijo. Rezultati prikazujejo učinkovitost vektorskega vodenja za povečanje okretnosti letalnega sistema.
Keywords: vektorsko vodenje, zračni potisk, letalstvo, okretnost, zaprto-zančni sistem
Published in DKUM: 05.10.2023; Views: 314; Downloads: 35
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