Wyniki wyszukiwania - BazTech

1

MEMS technology quality requirements as applied to multibeam echosounder

Bikonis K., Demkowicz J.

Polish Maritime Research

|

2018

|

nr 4

59--64

EN

Small, lightweight, power-efficient and low-cost microelectromechanical system (MEMS) inertial sensors and microcontrollers available in the market today help reduce the instability of Multibeam Sonars. Current MEMS inertial measurement units (IMUs) come in many shapes, sizes, and costs — depending on the application and performance required. Although MEMS inertial sensors offer affordable and appropriately scaled units, they are not currently capable of meeting all requirements for accurate and precise attitudes, due to their inherent measurement noise. The article presents the comparison of different MEMS technologies and their parameters regarding to the main application, namely Multibeam Echo Sounders (MBES). The quality of MEMS parameters is crucial for further MBES record-processing. The article presents the results of undertaken researches in that area, and these results are relatively positive for low-cost MEMS. The paper undertakes some vital aspect of using MEMS in the attitude and heading reference system (AHRS) context. The article presents a few aspects of MEMS gyro errors and their estimation process in the context of INS processing flow, as well as points out the main difficulties behind the INS when using a few top MEMS technologies.

2

MEMS technology evaluation for submerged vehicle navigation

Demkowicz J.

Hydroacoustics

|

2017

|

Vol. 20

35--40

EN

The article undertakes analysis of some vital aspects of inertial navigation using MEMS. Although MEMS inertial sensors offer affordable, scaled units, and though their inherent measurement noise can be relatively easily mitigated, there are still parameters due to which they are not currently capable of meeting all requirements for accurate inertial navigation. The article presents a few aspects of MEMS gyro errors, and their estimation process in the context of INS processing flow. These errors have a serious impact on overall inertial system performance. The results of undertaken researches in that area, and pointing out the main difficulties behind the INS when using a few top MEMS technologies, were presented as well. The paper clearly states, that current MEMS technologies, including sophisticated software, does not fulfil submerged inertial navigation whilst operating in dynamic conditions, due to linear acceleration, affecting gyro performance.

3

Inertial sensors applications in underwater measurements

Bikonis K., Demkowicz J.

Hydroacoustics

|

2017

|

Vol. 20

13--18

EN

Over the past decades microelectromechanical systems (MEMS) researchers have demonstrated a number of microsensors for almost every possible sensing modality, including attitudes. Current MEMS inertial measurement units (IMU) come in many shapes, sizes, and costs — depending on the application, and performance required. MEMS sensors have proved and demonstrated performance exceeding those of their macroscale counterpart sensors. In the paper chosen IMU applications in underwater measurements are presented. First, for reduction of instability of the underwater sensor during measurements, like multibeam echosounder system (MBES), where the MEMS parameters’ quality are crucial for further MBES record-processing. Second, in underwater navigation systems, for determining the position of underwater vehicles, like Remotely Operated Vehicles (ROV) and, more recently, Autonomous Underwater Vehicle (AUV) or to improve other positioning methods.

4

MEMS technology quality requirements as applied to multibeam echosounder

Demkowicz J., Bikonis K.

Hydroacoustics

|

2016

|

Vol. 19

75--82

EN

Small, lightweight, power-efficient, and low-cost microelectromechanical system (MEMS) inertial sensors and microcontrollers, available in the market today, help reduce the instability of Multibeam Sonars. Current MEMS inertial measurement units (IMUs) come in many shapes, sizes, and costs — depending on the application and performance required. Although MEMS inertial sensors offer affordable, appropriately scaled units, they are not currently capable of meeting all requirements for accurate and precise attitudes, due to their inherent measurement noise. The article presents the comparison of different MEMS technologies, and their parameters regarding to the main application; namely, Multibeam Echo Sounders (MBES). The MEMS parameters’ quality are crucial for further MBES record- processing, the article presents the results of undertaken researches in that area, and the results are relatively positive for low-cost MEMS.

5

EGNOS-Based GNSS receiver for precise positioning in restricted areas

Demkowicz J., Bikonis K.

Hydroacoustics

|

2016

|

Vol. 19

65--73

EN

Positioning accuracy is very important in many areas, whereas the typical GPS receiver accuracy is often not sufficient. The European Geostationary Navigation Overlay Service (EGNOS), Europe’s first venture into satellite navigation, improves the open public service offered by the Global Positioning System (GPS). As a satellite navigation augmentation system, EGNOS improves the accuracy of GPS by providing a positioning accuracy to within 3 meters. In this paper we present GNSS receivers based on EGNOS, dedicated for precise positioning in restricted areas of continental shelf performance. The article presents some results regarding position accuracy, obtained for a few receivers in that context.

6

Design of the dual constellation GPS/GALILEO mobile device for improving navigation of the visually impaired in an urban area

Drypczewski K., Moszyński M., Demkowicz J., Bikonis K., Stepnowski A.

Polish Maritime Research

|

2015

|

nr 4

15--20

EN

The article discusses damages of essential tribological associations in crankshaft and piston systems of large power two-stroke engines used as main engines, which take place during transport tasks performed by those ships. Difficulties are named which make preventing those damages impossible, despite the fact that the technical state of engines of this type is identified with the aid of complex diagnostic systems making use of advanced computer technology. It is demonstrated that one of causes of the damages is the lack of research activities oriented on recognising random properties of the loads leading to those damages. A proposal is made for the loads acting at a given time t on tribological associations in crankshaft and piston systems of internal combustion engines used as main engines to be considered as random variables Qt. At the same time the loads examined within a given time interval tr ≤ t ≤ tz would be considered stochastic processes {Q(t): t ≥ 0}. Essential properties of the loads of the abovementioned tribological associations are named and explained by formulating hypotheses which need empirical verification. Interval estimation is proposed for estimating the expected value E(Qt) of the load Qt acting at time t. A relation is indicated between the mechanical load and the thermal load acting on tribological associations in the ship main engine crankshaft and piston system. A suggestion is formulated that a stochastic form of the relation between these types of load is to be searched for, rather than statistic relation, and a proposal is made to measure the intensity (strength) of the stochastic relation using the Czuprow’s convergence coefficient.

7

Submerged objects modeling and storing in a global reference context using multiresolution spline technique

Demkowicz J.

Hydroacoustics

|

2015

|

Vol. 18

47-52

EN

Contemporary sensors i.e. multibeam sonars, 3D shuttle radar topography mission elevation data features high resolution. On the other side bathymetric models of different resolution from different sensors are available as well, starting from very high resolution MBS records as well as low resolution records coming from regular scattered measurement. Approximating and eventually visualizing high volume scattered 3D raster data of different resolution results in some difficulties related to computer processing power. The paper presents some advantages of using multiresolution splines combined with the Hilbert curve approach. The proposed approach consists of two stages: firstly, data of different resolution are interpolated using spline technique and finally the knots and control points are saved using the Hilbert curve. Such an approach especially facilitates high volume spatial data level of details (LoD) visualization technique.

8

Data Integration from GPS and Inertial Navigation Systems for Pedestrians in Urban Area

Bikonis K., Demkowicz J.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2013

|

Vol. 7, no. 3

401--406

EN

The GPS system is widely used in navigation and the GPS receiver can offer long-term stable absolute positioning information. The overall system performance depends largely on the signal environments. The position obtained from GPS is often degraded due to obstruction and multipath effect caused by buildings, city infrastructure and vegetation, whereas, the current performance achieved by inertial navigation systems (INS) is still relatively poor due to the large inertial sensor errors. The complementary features of GPS and INS are the main reasons why integrated GPS/INS systems are becoming increasingly popular. GPS/INS systems offer a high data rate, high accuracy position and orientation that can work in all environments, particularly those where satellite availability is restricted. In the paper integration algorithm of GPS and INS systems data for pedestrians in urban area is presented. For data integration an Extended Kalman Filter (EKF) algorithm is proposed. Complementary characteristics of GPS and INS with EKF can overcome the problem of huge INS drifts, GPS outages, dense multipath effect and other individual problems associated with these sensors.

9

Multibeam sonar records data decimation using hierarchical spline interpolation

Demkowicz J.

Hydroacoustics

|

2013

|

Vol. 16

41--46

EN

Multibeam sonar records feature high vertical and horizontal resolution. Interpolating and approximating and eventually displaying scattered 3D raster data of high volume leads to some difficulties related to a computer processing power. The paper presents some advantages of using hierarchical splines. The proposed approach consists of two stages: firstly, all acquired multibeam sonar raw data are interpolated with high density uniform spline interpolation. The knots and control points of interpolated network are saved for defined resolution level. In the next stage preprocessed high resolution data are combined with low resolution data sets following prior knot decimation process. Such approach allow real time 3D displaying of multibeam sonar data for different zoom levels.

10

Integration of inertial sensors and GPS system data for underwater navigation

Bikonis K., Demkowicz J., Stepnowski A.

Hydroacoustics

|

2012

|

Vol. 15

21-26

EN

The Inertial Navigation System (INS) is usually employed to determine the position of an underwater vehicles, like Remotely Operated Vehicles (ROV) and, more recently, Autonomous Underwater Vehicle (AUV). The accuracy of the position provided by the INS, which uses accelerometers and gyroscopes, deteriorates with time. An external aiding sources such as the Global Positioning System (GPS) can be employed to reduce the error growth in the INS. The GPS aided INS system provides enhance positioning accuracy of the underwater vehicles compared to that of a stand-alone INS technique. In the paper integration algorithm of inertial sensors (accelerometers and gyroscopes) and GPS system data for underwater navigation is presented. For data integration algorithm External Kalman Filter (EKF) is proposed.

11

Wykorzystanie wielorozdzielczych funkcji sklejanych do reprezentacji danych o zróżnicowanej rozdzielczości przestrzennej

Demkowicz J.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

|

2008

|

T. 16

347-352

PL

Interpolacja, aproksymacja a ostatecznie wizualizacja danych 3D o zróżnicowanej rozdzielczości w różnych skalach, stanowi duże utrudnienie w całym procesie analizy numerycznej. Artykuł prezentuje zalety związane z reprezentacją takich danych z wykorzystaniem kardynalnych funkcji sklejanych. Dla różnych skal zachowywane są węzły i punkty kontrolne tych funkcji, ale tylko miejscowo, dla wybranych, gęstych przestrzennie danych zachowywana jest informacja o zwiększonej rozdzielczości. Takie spójne podejście dla obydwu rodzajów danych umożliwia zastosowanie prostszych algorytmicznie rozwiązań odpowiedzialnych za spójne przechowywanie i wizualizację obiektów, które wymagają zróżnicowanego co do szczegółów opisu 3D.

EN

Multibeam sonar records are an example of a high resolution raster spatial data. Unfortunately, interpolating and approximating and eventually displaying scattered 3D raster data of high volume leads to same difficulties related to a computer processing rower. The proposed approach is two folded: firstly, all acquired highe resolution multibeam sonar raw bathymetric data are interpolated with high density uniform spline interpolation. The knots and control points of interpolated network are saved for defined resolution level. In the next stage preprocessed high resolution data are combined with law resolution data sets after knot decimation process.

12

Tworzenie numerycznej mapy 3D terenu na podstawie zdjęć satelitarnych z wykorzystaniem stereoskopowej techniki obrazowania

Łuba M., Demkowicz J.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

|

2008

|

T. 16

315-320

PL

W artykule przedstawiona została technika tworzenia map numerycznych na podstawie zdjęć satelitarnych wykonanych przez satelitę systemu IKONOS. Do przetwarzania wyżej wymienionych zdjęć została zastosowana technika stereoskopowego obrazowania, pozwalająca uzyskać dodatkową informację o głębi oraz trójwymiarowych zależnościach występujących pomiędzy obiektami obecnymi na zobrazowaniu. Zaprezentowana technika jest szczególnie użyteczna w procesie tworzenia trójwymiarowych map numerycznych.

EN

This investigation bas shown that Ikonos Geo stereo imagery bas the potential to yield 1m geopositioning accuracies. These results are quite impressive in an urban reconstruction. Unfortunately the results most take into account same notable shortcomings of 1m satellite imagery for building feature reconstruction. Though identifying all buildings of a certain size is quite optimistic, but it is not possible without, to same extends generalization.

13

System synchronizacji czasowej z wykorzystaniem odbiorników systemu GPS

Demkowicz J., Ogonowski A.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

|

2008

|

T. 16

341-346

PL

W artykule przedstawiono system synchronizacji czasowej zrealizowany w ramach projektu zewnętrznego zleconego Katedrze Systemów Geoinformatycznych Politechniki Gdańskiej. Podstawową funkcją systemu jest synchronizacja czasowa urządzeń lądowych i urządzeń poruszających się po wodzie, w celu precyzyjnego określenia pozycji a tym samym parametrów fizycznych dużych statk6w morskich. Zleceniodawcą projektu było Centrum Morskich Technologii Militarnych. System by! elementem dużego zadania projektowego.

EN

The paper presents results of project for Maritime Military Technology Center, which consisted in precise synchronization of independent devices equipped with GPS receivers. The project was conducted by Geoinformatics Department of Gdansk University of Technology. The overall system was a crucial part of a large ship demagnetization project realized by MMTC and was successfully finished and integrated.

14

Galileo satellite navigation system receiver concept

Lemanczyk M., Demkowicz J.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

|

2007

|

Vol. 1, no. 4

375--378

EN

The paper presents the Galileo Satellite Navigation System’s Receiver concept. The receiving path and the model of GNSS receiver system for the L1 signal was shown as well as Galileo services and fre-quencies were presented.

15

Rozproszony system akwizycji, prezentacji i analizy informacji przestrzennej

Gwaj K., Adamowicz R., Demkowicz J., Lubniewski Z.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

|

2006

|

T. 10

331-338

PL

W artykule przedstawiono skalowalny system prezentacji danych przestrzennych pochodzących z różnych źródeł, ze szczególnym uwzględnieniem specyfikacji Open Geospatial Consortium (OGC). System został zaimplementowany w technologii .NET i pracuje w środowisku rozproszonym w oparciu o Web Service. Aplikacja zrealizowana jest w formie apletu .NET, dzięki czemu można ją w prosty sposób osadzić w dokumencie HTML i umieścić na serwerze (niestety na razie jedynie Internet Explorer obsługuje aplety .NET), lub uruchomić jako samodzielną aplikację systemu Windows. Zważywszy na ciągły rozwój technologii .NET w przyszłości aplikacja będzie mogła działać również na innych platformach systemowych takich jak Linux, czy Novel.

EN

The paper presents a scaleable, distributed GIS system for the spatial data representation origin from different sources. The application complies with OGC (Open Geospatial Consortium specification. The system is implemented in .NET technology and uses Web Services. The n purpose of the application is an education, however the application is rather technologic advanced.

16

Charakterystyki sygnału w realizacji software'owego odbiornika systemu GPS

Demkowicz J., Stepnowski A.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

|

2006

|

T. 11

783-787

PL

Realizacja odbiornika w postaci aplikacji komputerowej pozwala nie tylko na kilkukrotne obniżenie kosztów jego produkcji, ale również wykorzystanie procesora ogólnego przeznaczenia do zadań związanych z odbiorem sygnału GPS i określaniem pozycji, a tym samym uproszczenie systemu. Analiza procesu przetwarzania sygnału GPS z wykorzystaniem standardowych narzędzi kompilacji i debugging'u, pozwala na poznanie działania odbiornika GPS (bez zgłębiania wiedzy o hardware'rze), a jednocześnie poznanie zasady działania najpopularniejszego obecnie sytemu do prowadzenia nawigacji. W artykule przedstawiono charakterystyki sygnałów w realizacji takiego odbiornika dla częstotliwości L l.

EN

The paper presents the characteristics of GPS signal of the non-real time software GPS receiver implementation. The receiver was implemented in C language and Matlab. This is very preliminary version of the software, with Some of the most important features as an satellite signal acquisition and tracking. The code optimization for fully featured the real-time GPS software receiver is under development.

17

3D visualisation and monitoring of marine pollutant aggregations in web-based GIS

Łubiniewski Z., Bikonis K., Demkowicz J., Partyka A., Stepnowski A.

Hydroacoustics

|

2006

|

Vol. 9

103-108

EN

The paper presents the visualisation and monitoring of marine pollutant aggregations as the sample application of the real-time, remotely accessible marine GIS. The system is dedicated for instantaneous integration, processing and visualisation of marine data acquired by direct sampling, satellite remote sensing and underwater acoustic systems. The developed Web-based GIS is capable of producing 2D maps with overlaid various types of data, as well as generating the composed, time-varying 3D scenes presenting different elements of marine environment. As the sample application of the system, the visualisation of the 3D modelling of an oil spill drift and spreading within the southern Baltic area is presented. The data were obtained from the composed 3D modelling system CAROCS. The developed GIS, due to its remote accessibility and the on-line data processing, may be applied as a useful tool for maritime domain awareness and emergency management supporting, with respect to hazard of a different kind: pollution, ecological catastrophes, natural disasters. The system utilises the SQL spatial database for data storage and the Scalable Vector Graphics (SVG) and Virtual Reality Modelling Language (VRML) standards for remote presentation of geographical objects, and requires only the WWW browser with SVG and VRML viewer on the client side.

18

Organizacja danych hipsograficznych na mapach numerycznych dla potrzeb trójwymiarowej wizualizacji obszarów o zasięgu globalnym

Demkowicz J.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

|

2005

|

T. 7

489-494

PL

Zasadniczym problemem wizualizacji obszarów o zasięgu globalnym jest duża ilość danych przy zachowywaniu możliwie dużej rozdzielczości, która ostatecznie decyduje o dokładności zobrazowania a tym samym o jego przydatności. Zagadnienie to szerzej znane jest jako skalowanie lub generalizacja. W szczególności problemem jest sam sposób przechowywania danych dla dużych obszarów. W artykule przedstawiono sposób przechowywania danych hipsograficznych z punktu widzenia wizualizacji trójwymiarowej na mapach numerycznych, opierający się min. na szeregach Mortona. Przedstawiono również efekty trójwymiarowej wizualizacji rejonu Pomorza Gdańskiego.

EN

The paper presents a proposition of the hypsographic data organization of large areas, in particular for the whole Earth. The proposed method is the Morton sequence spatial data organization. Some 3D visualizations for the Pomeranian Area, based on such hypsographic data organization are also presented.

19

Instalacja i wstępna analiza danych batymetrycznych pochodzących z echosondy wielowiązkowej

Demkowicz J., Bikonis K.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

|

2005

|

T. 7

495-502

PL

W akustycznym telemonitoringu środowiska morskiego stosowane są dwa rodzaje sonarów, a mianowicie: sonary boczne i echosondy wielowiązkowe. Oba systemy dostarczają danych zarówno dla batymetrii, jak i dla akustycznego obrazowania dna morskiego. Echosondy wielowiązkowe są zaawansowanymi technologicznie urządzeniami, które dzięki wielokierunkowej obserwacji szerokokątnej dna, przy jednoczesnym utrzymaniu wysokiej rozdzielczości kątowej, pozwalają na doskonałą batymetrię i obrazowanie dna morskiego z odbieranych sygnałów echa. Artykuł prezentuje rezultaty instalacji, uruchomienia i wstępnej analizy danych uzyskanych z rzeczywistych pomiarów batymetrycznych za pomocą wysokorozdzielczej echosondy wielowiązkowej firmy Konsgberg. Zaprezentowano również sposoby prezentacji danych, główne źródła błędów oraz sposoby ich rozpoznawania.

EN

Multibeam sonar is an advanced technology for the seafloor mapping. The paper presents Some technical aspects of multibeam processing technology, sources and types of errors and finaly 3D vizualization of raw data acquired by multibeam echosounder EM 3002.

20

Application of CDMA modulated signals in seafloor remote sensing

Demkowicz J., Łubiniewski Z.

Hydroacoustics

|

2005

|

Vol. 8

15-22

EN

The paper investigates the application of digital modulation access technique called Code Division Multiple Access (CDMA) to remote sensing of a seafloor. In a traditional sonar, the next ping cannot be sent until the echo from previous transmission has been received by the sonar transducer. As a result, such a sonar system is characterized by low duty ratio what causes the decrease of data resolution especially for larger depths. Using the CDMA modulation technique, may reduce pulse repetition rate. In the CDMA technique, each sonar pulse consists of several multiple narrow pulses, where each is encoded with a phase shift 0 or đ based on a spreading code. The paper presents the performance investigation results for this modulation scheme as applied both to transmitted and seafloor backscattered signal. The bottom backscattering was modeled numerically for typical bottom material and morphology. The advantages and constraints of the proposed technique were discussed in the context of echo detection and usefulness in acoustic seafloor characterization.