Ákos Odry | University of Dunaújváros (original) (raw)

Papers by Ákos Odry

2017 Fourth International Conference on Mathematics and Computers in Sciences and in Industry (MCSI), 2017

This research presents a simulation and optimization environment for developing motor controllers... more This research presents a simulation and optimization environment for developing motor controllers. There are various type of controllers which may provide better or worse performance for the intended use. Our fuzzy controller was developed and optimized in order to ensure better control performance and to protect the walking robot's electro-mechanical equipment against high peaks or jerks. This fuzzy controller was compared to a simple PID controller to show its advantage. Both controllers were optimized and competed on the same test situations. The control performance robustness against the motor and load parameters are evaluated. A simplified robot leg model was used to ensure a realistic load for the motor driving, instead of the full robot dynamic model because of its fast calculation. The developed fuzzy controller resulted better performance and robustness compared to the optimized PID.

Symmetry, 2021

This note presents a fuzzy optimization of Gabor filter-based object and text detection. The deri... more This note presents a fuzzy optimization of Gabor filter-based object and text detection. The derivation of a 2D Gabor filter and the guidelines for the fuzzification of the filter parameters are described. The fuzzy Gabor filter proved to be a robust text an object detection method in low-quality input images as extensively evaluated in the problem of license plate localization. The extended set of examples confirmed that the fuzzy optimized Gabor filter with adequately fuzzified parameters detected the desired license plate texture components and highly improved the object detection when compared to the classic Gabor filter. The robustness of the proposed approach was further demonstrated on other images of various origin containing text and different textures, captured using low-cost or modest quality acquisition procedures. The possibility to fine tune the fuzzification procedure to better suit certain applications offers the potential to further boost detection performance.

2020 IEEE 18th International Symposium on Intelligent Systems and Informatics (SISY), 2020

The aim of this paper is to introduce a novel robot leg design which will be used in the next gen... more The aim of this paper is to introduce a novel robot leg design which will be used in the next generation of the Szabad(ka) robots, the Szabad(ka) III hexapod robot. This new prototype has significant improvements compared to the previous leg used in the Szabad(ka) II robot. The design is based on a differential gear drive system. Most of the parts were created using modern 3D printing technology. A triple spring-damper system has further improved the functionality of the leg. A new, self-designed motor driver ensures appropriate control and sensor sampling at the expected frequencies. The next step of the research will be to carry out the structural optimization of the robot based on the new leg design. The optimization will determine the connection positions and the dimensions of the body and legs as well as the parameters of the triple spring damper system.

The oxygen plays an important role in the development and function of the human brain. In the cen... more The oxygen plays an important role in the development and function of the human brain. In the central nervous system, a different neuron types can be very sensitive to varying concentrations of oxygen. Despite several cell biology researches, the time course of the effects of non-physiological oxygen concentrations, but especially high oxygen concentrations on the membrane of neurons, and the dynamics of damage are unknown. In the present study, with this in view, electrical impedance spectroscopy (EIS) measurements are carried out using a graphene-based self-developed four-electrode measurement and data collection process. Our goal was to produce a plate layout for our further experiments that could be used to examine cell cultures under hypoxic and hyperoxic conditions. The designs differ in the distance between the electrodes, we used three types of distances: 1 mm, 3 mm 5 mm, using one distance per plate. On the plate with 5 mm electrode spacing we found the ideal. From a measur...

This paper presents the applications of depth cameras in robotics. The aim is to test the capabil... more This paper presents the applications of depth cameras in robotics. The aim is to test the capabilities of depth cameras in order to better detect objects in images based on depth information. In the paper, the Intel RealSense depth cameras are introduced briefly and their working principle and characteristics are explained. The use of depth cameras in the example of painting robots is shown in brief. The utilization of the RealSense depth camera is a very important step in robotic applications, since it is the initial step in a series of robotic operations, where the goal is to detect and extract an obstacle on a wall that is not intended for painting. A series of experiments confirmed that camera D415 provides much more precise and accurate depth information than camera D435. Key-Words: Depth image; measuring depth; RealSense cameras; image processing; obstacle detection.

The two-wheeled mobile pendulum system is a special mobile robot having two-wheels, two contact p... more The two-wheeled mobile pendulum system is a special mobile robot having two-wheels, two contact points with the supporting surface and its center of mass is located under the wheel axis. Due to the mechanical structure, the intermediate body tends to oscillate during the translation motion of the robot thus the application of modern control methods is essential in order to stabilize the dynamical system. In this paper, we introduce the mechatronics construction of the robot and derive its corresponding nonlinear mathematical model as well. Key-Words: mobile robot, mathematical modelling, self-balancing robot, future transportation system

IEEE Access, 2021

In stochastic computing (SC) systems numbers are represented with mean values of random binary se... more In stochastic computing (SC) systems numbers are represented with mean values of random binary sequences. This paper introduces a novel fuzzy inference architecture, in which the computational mechanism is based on stochastic logic (SL). First, the basic concept of SL is described, then the architecture of the SL-based fuzzy logic controller (SFLC) is built up systematically using the derived stochastic elements. The second part of the paper demonstrates the application of the proposed techniques, where the SFLC-based control performance is evaluated on a real mechatronic system. The results show that the SL-based approach provides effective and robust control performance, simple architecture and high noise tolerance. The proposed method is also benchmarked against conventional FLCs indicating that the robustness of the stochastic architecture allowed to outperform the benchmark controllers in noisy environments.

IEEE Sensors Journal

A simulation model contributes to the development of both algorithms based on navigation sensors ... more A simulation model contributes to the development of both algorithms based on navigation sensors and their application in real nonlinear mechatronic systems. The Szabad(ka)-II hexapod walker robot is equipped with an inertial measurement unit (IMU), and this paper presents a novel calibration procedure of its simulation model. Various sinusoidal calibration movements were performed on both the model and the robot, and the raw IMU measurements were recorded simultaneously with motor electrical parameters and joint movement variables. The simulation model includes the model of IMU sensors, where the location, misalignments, and scaling parameters are also incorporated in the tuning procedure. Thus, this simulation environment enabled the calibration procedure to be performed based on the measurement data. The efficient optimization of both the unknown and estimated parameters of the robot model along with the IMU sensor model resulted in a simulation output that fits the measurement results satisfactorily. The nominal and remaining errors were analyzed both statistically and in the spectral domain. Due to the proposed method, the simulation error of the accelerometer and gyroscope measurements were decreased by 35%. The necessity of calibrating the sensor model was justified via the application of an extended Kalman filter (EKF) for the attitude estimation.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

As material analysis method, the bioimpedance spectroscopy (BIS) is an effective technique to obt... more As material analysis method, the bioimpedance spectroscopy (BIS) is an effective technique to obtain material characteristics in many biological applications. Among the BIS models, the single-dispersion RC model and the Cole-Cole model constitute the fundamental mathematical descriptions for BIS measurements. These models enable both the evaluation of impedance spectrum and derivation of core parameters that describe biological processes. This paper presents the application of the particle swarm optimization (PSO), as a flexible heuristic optimization approach, to both derive the model parameters and characterize biological media based on BIS measurements. First, the fundamental modeling approaches are addressed and the core parameters are discussed. Moreover, the employed electrical impedance measuring instrument and conducted experiments are presented. Then, a multi-objective fitness function is established for the usage of the PSO algorithm for model parameter optimization. The paper demonstrates two case studies, namely, BIS measurements are performed to monitor i) liver fat and characterize its state with an optimized Cole-Cole model and ii) cell culture growth and characterize its state with an optimized single-dispersion RC model. It is shown with experimental results that PSO is an effective and robust tool to fit these biological models to BIS measurements. Additionally, the experimental results also highlight that the cell culture growth process cannot be modeled properly with the single-dispersion RC model in high frequency ranges. This experimental observation establishes the demand for the derivation of a more sophisticated mathematical model for the comprehensive characterization of cell culture growth in wide frequency spectrum.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

The four-electrode system is often applied to examine the dielectric properties of biological sam... more The four-electrode system is often applied to examine the dielectric properties of biological samples in low frequency range because the four-electrode method can be used to avoid measurement inaccuracies due to electrode polarization. This study is aiming to create four-electrode sensors that can provide reliable data about measuring cells even at low frequencies. Graphene and indium tin oxide (ITO) covered macroelectrodes were fabricated and compared, using electrical impedance spectroscopy (EIS). Impedance measurements were performed with solution series of NaCl. The impedance values of NaCl concentrations were not significantly different for the graphene and ITO electrodes but the standard deviation of data were larger for ITO electrodes than for graphene electrodes. Based on our investigations, the graphene-coated four-electrode sensor can provide cost-effective and sensitive measurements in the study of alpha and beta dispersions of cells.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

In Hungary, cancer causes a quarter of all deaths. Our goal is to develop a method of early diagn... more In Hungary, cancer causes a quarter of all deaths. Our goal is to develop a method of early diagnosis. Our research team is developing a new non-invasive bioimpedance spectrometry-based procedure that enables early detection of cancers. The measurement procedure as well as the instruments used for the measurement have been specially developed to measure tumor cells. The system, which is entirely self-developed, is an innovative solution for eliminating contact impedance due to the agility of the ions during the two electrode measurements known to this time. In our article, we present a cell culture plate that generates data that is free from the distractions of the aforementioned contact impedance. During the physical validation, we have demonstrated that the methodology we have developed can be used in a wide frequency range, so it is therefore fully suitable for further cellular testing.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

Compacted neurons are morphologically changed axons in an undamaged environment, which are able t... more Compacted neurons are morphologically changed axons in an undamaged environment, which are able to recover spontaneously. They may play an important role in neurological disorders, such as Parkinson’s disease or Alzheimer’s disease. The aim of this study was to find the best method for the investigation of this process. Therefore we designed and selfmade bio-impedance spectrum (BIS) measurement plates with three different electrode distances (1mm, 3mm, 5mm). Due to measurements using self-developed software, we got the result that plates with 3mm and 5mm distance setups are suitable for our future research studies. The validation measurement was carried out with series of solutions made of ion exchanged water and physiological saline solution (concentrations: 0%, 25%, 50%, 75%, and 100%) Due to successful plate development, it became possible to continuously measure the process of compaction and recovery of the dark neurons, and find out the details of this phenomenon.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

Nowadays, the gold standard for the diagnosis of liver disease is histological examination. Howev... more Nowadays, the gold standard for the diagnosis of liver disease is histological examination. However, due to the dangers and complications of liver biopsy, there is a worldwide demand for the development of non-invasive procedures that can accurately determine the degree of hepatic steatosis, furthermore is cost-effective, user-friendly, and provides repeatable measurement. Based on the metrological experience of our research team, we started developing an electrical impedance-based diagnostic method a few years ago that meets these requirements and is suitable for early detection of nonalcoholic fatty liver disease (NAFLD) with the help of a worldnew measurement and data collection solution. In addition to the preliminar results of the long-term clinical validation of the diagnostic method developed to detect NAFLD, the authors present early partial results. Even with the small amount of data, very impressive results have been obtained.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

Non-alcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease worldwide, ... more Non-alcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease worldwide, it is the primary cause of liver-related morbidity and mortality. The prevalence of the disease is estimated as high as 25% of the general population up to 90% of obese and diabetic patients. Most patients are asymptomatic or does not experience specific complaints making them difficult to diagnose and treat. However, due to the limitations of available diagnostic procedures and the current gold standard for diagnosis, the liver biopsy, there is a worldwide demand to develop a non-invasive diagnostic tool and procedure that can detect the disease with high accuracy at an early reversible stage, furthermore is cost-effective, user-friendly, and provides repeatable measurement. Based on the metrological experience of our research team, we started developing an electrical impedance-based diagnostic procedure a few years ago that meets these requirements and is suitable for early detection of NAFLD with the help of a world-new measurement and data collection solution. In this article, we present the most important milestones in the development of instruments related to research.

IEEE Access

This paper presents the use of the ZED depth sensor in a robot-based painting application. The us... more This paper presents the use of the ZED depth sensor in a robot-based painting application. The use of a stereo depth sensor is a very important factor in robotic applications, since it is both the initial and the essential step in a sequence of robotic operations, where the goal is to detect and extract the useful surface and objects or the obstacle on a wall that is not intended for painting. The ZED depth sensor was used for surface recording and navigation of our painting robot. Later, wall extraction was performed using simple image processing and morphological operations in a surface extraction algorithm. The goal was to use well-known, simple, and proven image processing operations in the algorithm to ensure both reliable and smooth operation of the robot's vision system in an industrial environment. The experiments showed that the developed algorithm detects and extracts the wall successfully under various depth measurement conditions. INDEX TERMS Depth image, image processing, obstacles, painting robot, ZED depth sensor.

Heliyon, Apr 1, 2020

A central goal of systems neuroscience is to simultaneously measure the activities of all achieva... more A central goal of systems neuroscience is to simultaneously measure the activities of all achievable neurons in the brain at millisecond resolution in freely moving animals. This paper describes a protocol converter which is part of a measurement acquisition system for multichannel real time recording of brain signals. In practice, in such techniques, a primary consideration of reliability leads to great necessity towards increasing the sampling rate of these signals while simultaneously increasing the resolution of A/D conversion to 24 bits or even to the unprecedented 32 bits per sample. In fact, this was the guiding principle for our team in the present study. By increasing the temporal and amplitude resolution, it is supposed that we get enabled to discover or recognize and identify new signal components which have previously been masked at a “low” temporal and amplitude resolution, and these new signal components, in the future, are likely to contribute to a deeper understanding of the workings of the brain.

IEEE Access

This paper presents a new algorithm for filtering and detecting circular and deformed circular ob... more This paper presents a new algorithm for filtering and detecting circular and deformed circular objects. The resulting procedure is based on fuzzifying the parameters of a circular Gabor filter to optimize the response of the circular Gabor filter and achieve additional selectivity of the filter. Circular and deformed circular objects of interest were efficiently extracted, and considerable resistance to noise and image degradation was achieved. INDEX TERMS Circular Gabor filters, fuzzification of filter parameters, fuzzy system, image filtering, image texture analysis, object detection.

2016 IEEE 11th International Symposium on Applied Computational Intelligence and Informatics (SACI), 2016

This paper investigates the performance of an optimized fuzzy control structure developed for the... more This paper investigates the performance of an optimized fuzzy control structure developed for the stabilization of a naturally unstable mechatronic system. The mechatronic system is a so-called mobile wheeled pendulum consisting of two actuated coaxial wheels and an inner body which oscillates (as a pendulum) around the wheel axis during planar motion. This motion is controlled in closed loop ensuring both the stabilization of the inner body as well as the planar motion of the wheels. The control structure comprises three fuzzy logic controllers whose input-output ranges and membership functions had been defined heuristically in an earlier study. This paper analyzes the achievable control performance through the formulation of a complex performance index and application of the particle swam optimization on the parameters of the control structure. The complex performance index took into account the reference tracking errors and the extent of inner body oscillation. The optimized fuzzy logic controllers showed a remarkable 29% overall performance improvement in the closed loop dynamics compared to the performance of the initial fuzzy control parameters. The simulation results proved that the optimized closed loop behavior protects more the electro-mechanical structure of the plant since the fast reference tracking performance was achieved along with effectively limited inner body oscillations.

2021 IEEE 19th International Symposium on Intelligent Systems and Informatics (SISY)

Nowadays, an increasing usage of autonomous mobile robots in outdoor applications can be noticed.... more Nowadays, an increasing usage of autonomous mobile robots in outdoor applications can be noticed. Identification of the terrain type is very important for efficient navigation. In this paper, a novel method is proposed for terrain classification in the case of wheeled mobile robots. The classification algorithm uses frequency domain features, which are extracted in fixed-size windows, and Multi-Layer Perceptron (MLP) neural networks as classifiers. Data from inertial sensors were collected for different outdoor terrain types using a prototype measurement system. The data of the accelerometer and the gyroscope were tested separately and together, and different processing window sizes were also applied. The achieved results show that above 99% classification efficiency can be achieved using the collected data.

Sensors

Accurate and reliable measurement of the electrical impedance spectrum is an essential requiremen... more Accurate and reliable measurement of the electrical impedance spectrum is an essential requirement in order to draw relevant conclusions in many fields and a variety of applications; in particular, for biological processes. Even in the state-of-the-art methods developed for this purpose, the accuracy and efficacy of impedance measurements are reduced in biological systems, due to the regular occurrence of parameters causing measurement errors such as residual impedance, parasitic capacitance, generator anomalies, and so on. Recent observations have reported the necessity of decreasing such inaccuracies whenever measurements are performed in the ultra-low frequency range, as the above-mentioned errors are almost entirely absent in such cases. The current research work proposes a method which can reject the anomalies listed above when measuring in the ultra-low frequency range, facilitating data collection at the same time. To demonstrate our hypothesis, originating from the considera...

2017 Fourth International Conference on Mathematics and Computers in Sciences and in Industry (MCSI), 2017

This research presents a simulation and optimization environment for developing motor controllers... more This research presents a simulation and optimization environment for developing motor controllers. There are various type of controllers which may provide better or worse performance for the intended use. Our fuzzy controller was developed and optimized in order to ensure better control performance and to protect the walking robot's electro-mechanical equipment against high peaks or jerks. This fuzzy controller was compared to a simple PID controller to show its advantage. Both controllers were optimized and competed on the same test situations. The control performance robustness against the motor and load parameters are evaluated. A simplified robot leg model was used to ensure a realistic load for the motor driving, instead of the full robot dynamic model because of its fast calculation. The developed fuzzy controller resulted better performance and robustness compared to the optimized PID.

Symmetry, 2021

This note presents a fuzzy optimization of Gabor filter-based object and text detection. The deri... more This note presents a fuzzy optimization of Gabor filter-based object and text detection. The derivation of a 2D Gabor filter and the guidelines for the fuzzification of the filter parameters are described. The fuzzy Gabor filter proved to be a robust text an object detection method in low-quality input images as extensively evaluated in the problem of license plate localization. The extended set of examples confirmed that the fuzzy optimized Gabor filter with adequately fuzzified parameters detected the desired license plate texture components and highly improved the object detection when compared to the classic Gabor filter. The robustness of the proposed approach was further demonstrated on other images of various origin containing text and different textures, captured using low-cost or modest quality acquisition procedures. The possibility to fine tune the fuzzification procedure to better suit certain applications offers the potential to further boost detection performance.

2020 IEEE 18th International Symposium on Intelligent Systems and Informatics (SISY), 2020

The aim of this paper is to introduce a novel robot leg design which will be used in the next gen... more The aim of this paper is to introduce a novel robot leg design which will be used in the next generation of the Szabad(ka) robots, the Szabad(ka) III hexapod robot. This new prototype has significant improvements compared to the previous leg used in the Szabad(ka) II robot. The design is based on a differential gear drive system. Most of the parts were created using modern 3D printing technology. A triple spring-damper system has further improved the functionality of the leg. A new, self-designed motor driver ensures appropriate control and sensor sampling at the expected frequencies. The next step of the research will be to carry out the structural optimization of the robot based on the new leg design. The optimization will determine the connection positions and the dimensions of the body and legs as well as the parameters of the triple spring damper system.

The oxygen plays an important role in the development and function of the human brain. In the cen... more The oxygen plays an important role in the development and function of the human brain. In the central nervous system, a different neuron types can be very sensitive to varying concentrations of oxygen. Despite several cell biology researches, the time course of the effects of non-physiological oxygen concentrations, but especially high oxygen concentrations on the membrane of neurons, and the dynamics of damage are unknown. In the present study, with this in view, electrical impedance spectroscopy (EIS) measurements are carried out using a graphene-based self-developed four-electrode measurement and data collection process. Our goal was to produce a plate layout for our further experiments that could be used to examine cell cultures under hypoxic and hyperoxic conditions. The designs differ in the distance between the electrodes, we used three types of distances: 1 mm, 3 mm 5 mm, using one distance per plate. On the plate with 5 mm electrode spacing we found the ideal. From a measur...

This paper presents the applications of depth cameras in robotics. The aim is to test the capabil... more This paper presents the applications of depth cameras in robotics. The aim is to test the capabilities of depth cameras in order to better detect objects in images based on depth information. In the paper, the Intel RealSense depth cameras are introduced briefly and their working principle and characteristics are explained. The use of depth cameras in the example of painting robots is shown in brief. The utilization of the RealSense depth camera is a very important step in robotic applications, since it is the initial step in a series of robotic operations, where the goal is to detect and extract an obstacle on a wall that is not intended for painting. A series of experiments confirmed that camera D415 provides much more precise and accurate depth information than camera D435. Key-Words: Depth image; measuring depth; RealSense cameras; image processing; obstacle detection.

The two-wheeled mobile pendulum system is a special mobile robot having two-wheels, two contact p... more The two-wheeled mobile pendulum system is a special mobile robot having two-wheels, two contact points with the supporting surface and its center of mass is located under the wheel axis. Due to the mechanical structure, the intermediate body tends to oscillate during the translation motion of the robot thus the application of modern control methods is essential in order to stabilize the dynamical system. In this paper, we introduce the mechatronics construction of the robot and derive its corresponding nonlinear mathematical model as well. Key-Words: mobile robot, mathematical modelling, self-balancing robot, future transportation system

IEEE Access, 2021

In stochastic computing (SC) systems numbers are represented with mean values of random binary se... more In stochastic computing (SC) systems numbers are represented with mean values of random binary sequences. This paper introduces a novel fuzzy inference architecture, in which the computational mechanism is based on stochastic logic (SL). First, the basic concept of SL is described, then the architecture of the SL-based fuzzy logic controller (SFLC) is built up systematically using the derived stochastic elements. The second part of the paper demonstrates the application of the proposed techniques, where the SFLC-based control performance is evaluated on a real mechatronic system. The results show that the SL-based approach provides effective and robust control performance, simple architecture and high noise tolerance. The proposed method is also benchmarked against conventional FLCs indicating that the robustness of the stochastic architecture allowed to outperform the benchmark controllers in noisy environments.

IEEE Sensors Journal

A simulation model contributes to the development of both algorithms based on navigation sensors ... more A simulation model contributes to the development of both algorithms based on navigation sensors and their application in real nonlinear mechatronic systems. The Szabad(ka)-II hexapod walker robot is equipped with an inertial measurement unit (IMU), and this paper presents a novel calibration procedure of its simulation model. Various sinusoidal calibration movements were performed on both the model and the robot, and the raw IMU measurements were recorded simultaneously with motor electrical parameters and joint movement variables. The simulation model includes the model of IMU sensors, where the location, misalignments, and scaling parameters are also incorporated in the tuning procedure. Thus, this simulation environment enabled the calibration procedure to be performed based on the measurement data. The efficient optimization of both the unknown and estimated parameters of the robot model along with the IMU sensor model resulted in a simulation output that fits the measurement results satisfactorily. The nominal and remaining errors were analyzed both statistically and in the spectral domain. Due to the proposed method, the simulation error of the accelerometer and gyroscope measurements were decreased by 35%. The necessity of calibrating the sensor model was justified via the application of an extended Kalman filter (EKF) for the attitude estimation.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

As material analysis method, the bioimpedance spectroscopy (BIS) is an effective technique to obt... more As material analysis method, the bioimpedance spectroscopy (BIS) is an effective technique to obtain material characteristics in many biological applications. Among the BIS models, the single-dispersion RC model and the Cole-Cole model constitute the fundamental mathematical descriptions for BIS measurements. These models enable both the evaluation of impedance spectrum and derivation of core parameters that describe biological processes. This paper presents the application of the particle swarm optimization (PSO), as a flexible heuristic optimization approach, to both derive the model parameters and characterize biological media based on BIS measurements. First, the fundamental modeling approaches are addressed and the core parameters are discussed. Moreover, the employed electrical impedance measuring instrument and conducted experiments are presented. Then, a multi-objective fitness function is established for the usage of the PSO algorithm for model parameter optimization. The paper demonstrates two case studies, namely, BIS measurements are performed to monitor i) liver fat and characterize its state with an optimized Cole-Cole model and ii) cell culture growth and characterize its state with an optimized single-dispersion RC model. It is shown with experimental results that PSO is an effective and robust tool to fit these biological models to BIS measurements. Additionally, the experimental results also highlight that the cell culture growth process cannot be modeled properly with the single-dispersion RC model in high frequency ranges. This experimental observation establishes the demand for the derivation of a more sophisticated mathematical model for the comprehensive characterization of cell culture growth in wide frequency spectrum.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

The four-electrode system is often applied to examine the dielectric properties of biological sam... more The four-electrode system is often applied to examine the dielectric properties of biological samples in low frequency range because the four-electrode method can be used to avoid measurement inaccuracies due to electrode polarization. This study is aiming to create four-electrode sensors that can provide reliable data about measuring cells even at low frequencies. Graphene and indium tin oxide (ITO) covered macroelectrodes were fabricated and compared, using electrical impedance spectroscopy (EIS). Impedance measurements were performed with solution series of NaCl. The impedance values of NaCl concentrations were not significantly different for the graphene and ITO electrodes but the standard deviation of data were larger for ITO electrodes than for graphene electrodes. Based on our investigations, the graphene-coated four-electrode sensor can provide cost-effective and sensitive measurements in the study of alpha and beta dispersions of cells.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

In Hungary, cancer causes a quarter of all deaths. Our goal is to develop a method of early diagn... more In Hungary, cancer causes a quarter of all deaths. Our goal is to develop a method of early diagnosis. Our research team is developing a new non-invasive bioimpedance spectrometry-based procedure that enables early detection of cancers. The measurement procedure as well as the instruments used for the measurement have been specially developed to measure tumor cells. The system, which is entirely self-developed, is an innovative solution for eliminating contact impedance due to the agility of the ions during the two electrode measurements known to this time. In our article, we present a cell culture plate that generates data that is free from the distractions of the aforementioned contact impedance. During the physical validation, we have demonstrated that the methodology we have developed can be used in a wide frequency range, so it is therefore fully suitable for further cellular testing.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

Compacted neurons are morphologically changed axons in an undamaged environment, which are able t... more Compacted neurons are morphologically changed axons in an undamaged environment, which are able to recover spontaneously. They may play an important role in neurological disorders, such as Parkinson’s disease or Alzheimer’s disease. The aim of this study was to find the best method for the investigation of this process. Therefore we designed and selfmade bio-impedance spectrum (BIS) measurement plates with three different electrode distances (1mm, 3mm, 5mm). Due to measurements using self-developed software, we got the result that plates with 3mm and 5mm distance setups are suitable for our future research studies. The validation measurement was carried out with series of solutions made of ion exchanged water and physiological saline solution (concentrations: 0%, 25%, 50%, 75%, and 100%) Due to successful plate development, it became possible to continuously measure the process of compaction and recovery of the dark neurons, and find out the details of this phenomenon.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

Nowadays, the gold standard for the diagnosis of liver disease is histological examination. Howev... more Nowadays, the gold standard for the diagnosis of liver disease is histological examination. However, due to the dangers and complications of liver biopsy, there is a worldwide demand for the development of non-invasive procedures that can accurately determine the degree of hepatic steatosis, furthermore is cost-effective, user-friendly, and provides repeatable measurement. Based on the metrological experience of our research team, we started developing an electrical impedance-based diagnostic method a few years ago that meets these requirements and is suitable for early detection of nonalcoholic fatty liver disease (NAFLD) with the help of a worldnew measurement and data collection solution. In addition to the preliminar results of the long-term clinical validation of the diagnostic method developed to detect NAFLD, the authors present early partial results. Even with the small amount of data, very impressive results have been obtained.

2021 IEEE 15th International Symposium on Applied Computational Intelligence and Informatics (SACI)

Non-alcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease worldwide, ... more Non-alcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease worldwide, it is the primary cause of liver-related morbidity and mortality. The prevalence of the disease is estimated as high as 25% of the general population up to 90% of obese and diabetic patients. Most patients are asymptomatic or does not experience specific complaints making them difficult to diagnose and treat. However, due to the limitations of available diagnostic procedures and the current gold standard for diagnosis, the liver biopsy, there is a worldwide demand to develop a non-invasive diagnostic tool and procedure that can detect the disease with high accuracy at an early reversible stage, furthermore is cost-effective, user-friendly, and provides repeatable measurement. Based on the metrological experience of our research team, we started developing an electrical impedance-based diagnostic procedure a few years ago that meets these requirements and is suitable for early detection of NAFLD with the help of a world-new measurement and data collection solution. In this article, we present the most important milestones in the development of instruments related to research.

IEEE Access

This paper presents the use of the ZED depth sensor in a robot-based painting application. The us... more This paper presents the use of the ZED depth sensor in a robot-based painting application. The use of a stereo depth sensor is a very important factor in robotic applications, since it is both the initial and the essential step in a sequence of robotic operations, where the goal is to detect and extract the useful surface and objects or the obstacle on a wall that is not intended for painting. The ZED depth sensor was used for surface recording and navigation of our painting robot. Later, wall extraction was performed using simple image processing and morphological operations in a surface extraction algorithm. The goal was to use well-known, simple, and proven image processing operations in the algorithm to ensure both reliable and smooth operation of the robot's vision system in an industrial environment. The experiments showed that the developed algorithm detects and extracts the wall successfully under various depth measurement conditions. INDEX TERMS Depth image, image processing, obstacles, painting robot, ZED depth sensor.

Heliyon, Apr 1, 2020

A central goal of systems neuroscience is to simultaneously measure the activities of all achieva... more A central goal of systems neuroscience is to simultaneously measure the activities of all achievable neurons in the brain at millisecond resolution in freely moving animals. This paper describes a protocol converter which is part of a measurement acquisition system for multichannel real time recording of brain signals. In practice, in such techniques, a primary consideration of reliability leads to great necessity towards increasing the sampling rate of these signals while simultaneously increasing the resolution of A/D conversion to 24 bits or even to the unprecedented 32 bits per sample. In fact, this was the guiding principle for our team in the present study. By increasing the temporal and amplitude resolution, it is supposed that we get enabled to discover or recognize and identify new signal components which have previously been masked at a “low” temporal and amplitude resolution, and these new signal components, in the future, are likely to contribute to a deeper understanding of the workings of the brain.

IEEE Access

This paper presents a new algorithm for filtering and detecting circular and deformed circular ob... more This paper presents a new algorithm for filtering and detecting circular and deformed circular objects. The resulting procedure is based on fuzzifying the parameters of a circular Gabor filter to optimize the response of the circular Gabor filter and achieve additional selectivity of the filter. Circular and deformed circular objects of interest were efficiently extracted, and considerable resistance to noise and image degradation was achieved. INDEX TERMS Circular Gabor filters, fuzzification of filter parameters, fuzzy system, image filtering, image texture analysis, object detection.

2016 IEEE 11th International Symposium on Applied Computational Intelligence and Informatics (SACI), 2016

This paper investigates the performance of an optimized fuzzy control structure developed for the... more This paper investigates the performance of an optimized fuzzy control structure developed for the stabilization of a naturally unstable mechatronic system. The mechatronic system is a so-called mobile wheeled pendulum consisting of two actuated coaxial wheels and an inner body which oscillates (as a pendulum) around the wheel axis during planar motion. This motion is controlled in closed loop ensuring both the stabilization of the inner body as well as the planar motion of the wheels. The control structure comprises three fuzzy logic controllers whose input-output ranges and membership functions had been defined heuristically in an earlier study. This paper analyzes the achievable control performance through the formulation of a complex performance index and application of the particle swam optimization on the parameters of the control structure. The complex performance index took into account the reference tracking errors and the extent of inner body oscillation. The optimized fuzzy logic controllers showed a remarkable 29% overall performance improvement in the closed loop dynamics compared to the performance of the initial fuzzy control parameters. The simulation results proved that the optimized closed loop behavior protects more the electro-mechanical structure of the plant since the fast reference tracking performance was achieved along with effectively limited inner body oscillations.

2021 IEEE 19th International Symposium on Intelligent Systems and Informatics (SISY)

Nowadays, an increasing usage of autonomous mobile robots in outdoor applications can be noticed.... more Nowadays, an increasing usage of autonomous mobile robots in outdoor applications can be noticed. Identification of the terrain type is very important for efficient navigation. In this paper, a novel method is proposed for terrain classification in the case of wheeled mobile robots. The classification algorithm uses frequency domain features, which are extracted in fixed-size windows, and Multi-Layer Perceptron (MLP) neural networks as classifiers. Data from inertial sensors were collected for different outdoor terrain types using a prototype measurement system. The data of the accelerometer and the gyroscope were tested separately and together, and different processing window sizes were also applied. The achieved results show that above 99% classification efficiency can be achieved using the collected data.

Sensors

Accurate and reliable measurement of the electrical impedance spectrum is an essential requiremen... more Accurate and reliable measurement of the electrical impedance spectrum is an essential requirement in order to draw relevant conclusions in many fields and a variety of applications; in particular, for biological processes. Even in the state-of-the-art methods developed for this purpose, the accuracy and efficacy of impedance measurements are reduced in biological systems, due to the regular occurrence of parameters causing measurement errors such as residual impedance, parasitic capacitance, generator anomalies, and so on. Recent observations have reported the necessity of decreasing such inaccuracies whenever measurements are performed in the ultra-low frequency range, as the above-mentioned errors are almost entirely absent in such cases. The current research work proposes a method which can reject the anomalies listed above when measuring in the ultra-low frequency range, facilitating data collection at the same time. To demonstrate our hypothesis, originating from the considera...