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  • 101.
    Mansouri, Sina Sharif
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Distributed Model Predictive Control for Unmanned Aerial Vehicles2015Ingår i: 2015 Workshop on Research, Education and Development of Unmanned Aerial Systems: RED-UAS 2015, Cancun, Mexico, 23 - 25 November 2015, Picataway, NJ: IEEE Communications Society, 2015, s. 152-161, artikel-id 7441002Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a distributed model pre- dictive control scheme, for the cooperative motion control of Unmanned Aerial Vehicles (UAVs) is be- ing presented. The UAVs are modeled by a 6-DOF nonlinear kinematic model. Two different control ar- chitectures: a centralized and a distributed MPC, are studied and evaluated in simulation experiments. In the centralized approach, one central MPC controller is responsible for the movement coordination of all the UAVs, while in the distributed approach each aerial vehicle plans only for its own actions, while the objective function is coupled with the behavior of the rest of the team members and the constraints are decoupled. In this approach, each agent only shares the future position of itself with the other agents to avoid collisions. For reducing the computation time and complexity, only one step ahead prediction in the corresponding MPC schemes have been considered without a loss of generality. Finally, the efficiency of the overall suggested decentralized MPC scheme, as well as it comparison with the centralized approach, is being evaluated through the utilization of multiple simulation scenarios.

  • 102.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Georgoulas, George
    Department of Informatics and Communications Technology, Technical Educational Institute of Epirus, 47100 Artas, Kostakioi.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Bearing fault classification based on minimum volume ellipsoid feature extraction2013Ingår i: 2013 IEEE Multiconference on Systems and Control (MSC), Hyderabad, India, August, 28-30, 2013, 2013, s. 1177-1182Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article presents a novel fault classification and diagnosis technique for bearings based on a Minimum Volume Ellipsoid (MVE) method for feature extraction. Data from two accelerometers located at two different sights of the test bed are combined to create a two dimensional representation and the feature extraction stage condenses that information using an ellipsoid description. The proposed features feed a simple non-linear classifier which separates almost perfectly between normal and faulty conditions, with also very high diagnostic accuracy between the faulty classes. The obtained results suggest that this novel representation can be used within a condition monitoring system.

  • 103.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Georgoulas, George
    Department of Informatics and Communications Technology, Technical Educational Institute of Epirus, 47100 Artas, Kostakioi.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Principal Component Analysis Anomaly Detector for Rotor Broken Bars2015Ingår i: IECON 2014: 40th Annual Conference of the IEEE Industrial Electronics Society, Dallas, TX, USA , Oct. 29 2014 - Nov. 1 2014, Piscataway, NJ: IEEE Communications Society, 2015, s. 3462-3467Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a method for the detection of broken rotor bars in asynchronous machines operating under full load is presented. Unlike most Motor Current Signature Analysis (MCSA) approaches, which operate in the frequency domain, our method operates in the time domain. The scheme is based on the use of a Principal Component Analysis (PCA) fault/anomaly detector applied on the three stator currents to calculate the Q statistic which is employed for detecting a fault. The efficiency of the proposed scheme was experimentally evaluated using different fault severity levels, ranging from 1/4 of a broken bar to three broken bars. The obtained results indicate that the method can detect the caused asymmetry with a very restricted amount of data.

  • 104.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Stator winding short circuit fault detection based on uncertainty ellipsoid intersection for three phase induction motors2013Ingår i: 10th International Conference on Informatics in Control, Automation and Robotics: Reykjavik, Iceland, 29-31, July, 2013, 2013, s. 206-212Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a fault detection scheme for different percentage of stator winding short circuit is presented for three phase induction motors. In the examined case, the induction motor in the faulty and healthy case has been transformed in the two phase (q−d) model. The model has been identified by the utilization of a Least Squares Set Membership Identification (SMI) algorithm, where additional to the identified parameters, confidence intervals can be also calculated, based on a priori knowledge for the corrupting measurement noise. The identified confidence intervals in an μ–dimensional space can be represented as hyper–ellipsoids having as a center the identified parameters’ vector. The novelty of this article stems from the proposal of a fast and geometrical based scheme, which relies on the calculation of the distance among centers of hyper–ellipsoids and the corresponding intersection in each iteration of the identification procedure. Detailed analysis of the proposed fault detection strategy, as also extended simulation results are being presented that prove the efficiency of the suggested scheme.

  • 105.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Georgoulas, George
    Department of Informatics and Communications Technology, Technical Educational Institute of Epirus, 47100 Artas, Kostakioi, Department of Computer Engineering, TEI of Epirus, Arta.
    Fault classification of Broken Rotor Bars in Induction Motors Based on Envelope Current Analysis2015Ingår i: IEEE 13th International Conference on Industrial Informatics (INDIN), 2015: Cambridge, United Kingdom, 22-24 July 2015, Piscataway, NJ: IEEE Communications Society, 2015, s. 795-800, artikel-id 7281838Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a method for the fault classification of one, two, and three broken bars in induction motors under full load condition is presented. The proposed methodology is based on the current envelope analysis, which in the past has been also widely utilized in analyzing the rotor faults at low slips. As it will be presented, the information obtained from the envelope current is valuable in manifesting and validating the presence of fault, since the current envelope and its characteristics often contains important information about the existence of a fault and the corresponding fault type. The proposed method mainly focuses on the case of steady-state operation under full load. In the established fault detection scheme, from the stator’s current six statistical features are extracted and utilized for the fault detection and classification. In more detail, three classifiers, a linear, a quadratic and a Nearest Neighbor have been investigated for the diagnosis of broken rotor bar faults of an induction motor. The presented approach have manifested promising results using experimental data.

  • 106.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    A fault diagnosis scheme for three phase induction motors based on uncertainty bounds2012Ingår i: IECON 2012: 38th Annual Conference of the IEEE Industrial Electronics Society, Piscataway, NJ: IEEE Communications Society, 2012, s. 1596-1601Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this article is to present a fault diagnosis scheme for the case of squirrel–cage Three Phase Induction Motors based on uncertainty bounds violation conditions. The suggested scheme has the capability to diagnose two types of faults: a) broken rotor bar and b) short circuit in stator winding. The fault diagnosis is being performed through a two steps procedure. In the first step the parameters of the healthy induction motor are being identified by utilizing a Set Membership Identification approach, where corresponding uncertainty bounds are also being provided. In the second step, specific proposed bound violation conditions for the fault detection and fault diagnosis are being on–line evaluated during a sliding time window. Multiple simulation results are being presented that prove the efficacy of the proposed scheme towards fault detection and fault diagnosis.

  • 107.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    A Robust Linear Discrimination Fault Classification Scheme for Three Phase Induction Motors2013Ingår i: CoDIT 2013: IEEE 2013 International Conference on Control, Decision and Information Technologies, Piscataway, NJ: IEEE Communications Society, 2013, s. 524-529Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a fault classification algorithm based on a robust linear discrimination scheme, for the case of a squirrel–cage three phase induction motor, will be presented. The suggested scheme is based on a novel feature extraction mechanism from the measured magnitude and phase of current park’s vector pattern. The proposed methodology has the merit to diagnose different types of faults such as: a) broken rotor bar, and b) short circuit in stator winding. The novel feature generation technique is able to transform the problem of fault detection and diagnosis into a simpler space, where direct robust linear discrimination can be applied for solving the classification problem. Robust linear discrimination has been one of the most widely used fault detection method in real life applications, as this methodology seeks for directions that are efficient for discrimination and at the same time requires a straight forward implementation. The efficacy of the proposed scheme will be evaluated based on multiple simulation results for different fault types.

  • 108.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    A survey on modeling approaches for three phase induction motors2012Ingår i: Proceedings of the IASTED International Conference on Modelling, Simulation and Identification / [ed] T. Znati; Z. Bar-Joseph; L. Rothrock, ACTA Press, 2012, s. 336-343Konferensbidrag (Refereegranskat)
    Abstract [en]

    Three–phase induction machines are generally being utilized as motors for many industrial systems, mainly due to their simple construction, low cost and other merits, when compared with other types of motors. The main aim of this article is to present a survey regarding the appeared approaches towards the mathematical modeling of three phase induction motors, which is the first step before designing appropriate control schemes. More analytically, two main modeling approaches will be presented: a) the complete three phase models, and b) the simplified quadra-ture phase models. Within these two main categories, all the types of the modeling approaches for induction motors will be presented, while the relevant significant applications, including the corresponding advantages and disadvantages for these models will be also presented. Finally, an extended bibliography is being provided as a base line for future investigations.

  • 109.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Broken Bars Fault Diagnosis Based on Uncertainty Bounds Violation for Three Phase Induction Motors2015Ingår i: International Transactions on Electrical Energy Systems, E-ISSN 2050-7038, s. 304-325Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, a novel fault diagnosis scheme, based on uncertainty bounds violation, is being presented for the case of broken bars in squirrel–cage Three Phase Induction Motors. The fault diagnosis is done in two steps. Firstly the parameters of the healthy induction motor are identified using a set member- ship identification (SMI) approach, where corresponding uncertainty bounds are also being provided. Secondly the proposed uncertainty bounds violation conditions for the fault diagnosis are evaluated on–line, on the converged identified model, during a sliding time window. Multiple simulation results are presented that demonstrate the efficacy of the proposed scheme towards fault detection and diagnosis among different number of broken bars.

  • 110.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Broken rotor bar fault detection based on uncertainty ellipsoidal intersection for three phase induction motors2013Ingår i: 21st IEEE Mediterranean Conference on Control and Automation, June 25-28, Platanias, Chania, Crete, Greece, 2013., Piscataway, NJ: IEEE Communications Society, 2013, s. 388-393, artikel-id 6608751Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a fault detection scheme for broken rotor bar fault detection in three phase induction motor is presented. In the proposed scheme the induction motor has been transformed in the equivalent two phase (q−d) space, while the modeling of the faulty case has been also formulated. The model has been identified by the utilization of the Set Membership Identification (SMI) algorithm that has the merit of identifying both the parameters of the motor as also providing uncertainty bounds in both the healthy and the faulty cases. Based on the adopted methodology, the uncertainty bounds and the corresponding identified parameters of the induction motor is presented as 3D–ellipsoids, while a novel fast and efficient fault detection scheme has been proposed that is able to track iteratively the ellipsoid centers, the distance among centers, the intersection between the initial and a priori known converged states of the motor and the current ones, before or after the fault occurrence. Detailed analysis of the proposed approach and he fault detection strategy, as also extended simulation results are being presented that prove the efficiency of the suggested scheme.

  • 111.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Experimental evaluation of a broken rotor bar fault detection scheme based on uncertainty bounds violation2013Ingår i: 39th Annual Conference of the IEEE Industrial Electronics Society: November 10-13, 2013, Vienna, Austria, IEEE Communications Society, 2013, s. 5541-5546Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article an experimental evaluation of a broken rotor bar fault detection scheme based on uncertainty bounds violation will be presented. The novelty of this article stems from the establishment and the experimental evaluation of fault detection scheme being able to detect faults at the beginning of its occurrence, based on Set Membership Identification and novel proposed boundary violation rules for the identified motor’s parameters. By the utilization of the SMI technique, the simplified equivalent model of the induction motor is being identified during the steady state operation (non–fault case), while at the same time safety bounds for the identified variables are being provided, based on an a priori defined corrupting additive noise. On the event of a fault, specific fault detection conditions are being proposed that can capture the fault of a broken bar. Detailed analysis of the proposed approach as also extended experimental results are being presented that prove the efficiency of the proposed scheme.

  • 112.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Fault classification scheme for three phase induction motor2014Ingår i: International Journal of System Dynamics Applications, ISSN 2160-9772, E-ISSN 2160-9799, Vol. 3, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article a fault classification algorithm based on a robust linear discrimination scheme, for the case of a squirrel–cage three phase induction motor, will be presented. The suggested scheme is based on a novel feature extraction mechanism from the measured magnitude and phase of current park’s vector pattern. The proposed methodology has the merit to diagnose different types of faults such as: a) broken rotor bar, and b) short circuit in stator winding. The novel feature generation technique is able to transform the problem of fault detection and diagnosis into a simpler space, where direct robust linear discrimination can be applied for solving the classification problem. Robust linear discrimination has been one of the most widely used fault detection method in real life applications, as this methodology seeks for directions that are efficient for discrimination and at the same time applies a straight forward implementation. The efficacy of the proposed scheme will be evaluated based on multiple simulation results for different fault types.

  • 113.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Fault detection based on set membership identification for three phase induction motors2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a fault detection scheme for stator winding short circuit fault detection in the case of a three phase induction motor is being presented. The three phase motor is model in (q-d) model space for the normal and the faulty case. The motor is being identified by the utilization of Set Membership Identification (SMI) that has the merit of identifying both the parameters of the motor as also providing uncertainty safety bounds by calculating orthotopes which bounds the system’s parameter vector. Based on the volume and the trend of these orthotopes, rules for identifying the existence of a fault are being presented. If the current values of the identified parameters do not lie inside the safety bounds in the healthy case, but lie in an area that is being defined by the model of the short circuit case, then a fault is being triggered.

  • 114.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Stator winding short circuit fault detection based on set membership identification for three phase induction motors2012Ingår i: 2012 20th Mediterranean Conference on Control and Automation: Barcelona, Spain, July 3-6, 2012, Piscataway, NJ: IEEE Communications Society, 2012, s. 290-296Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a fault detection scheme for stator winding short circuit fault detection in the case of a three phase induction motor is being presented. The three phase motor is being modeled in the equivalent two phase motor (q−d) space, while the modeling of the faulty case is being also formulated. The motor is being identified by the utilization of Set Membership Identification (SMI) that has the merit of identifying both the parameters of the motor as also providing uncertainty safety bounds by calculating orthotopes which bounds the systems parameter vector. Based on the volume and the trend of these orthotopes, rules for identifying the existence of a fault are being presented. If the current valuesof the identified parameters do not lie inside the safety bounds in the healthy case, but lie in an area that is being defined by the model of the short circuit case, then a fault is being triggered. Detailed analysis of the proposed approach as also extended simulation results are being presented that prove the efficiency of the suggested scheme.

  • 115.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Uncertainty Bounds Violation Scheme for Fault Detection in Induction Motors: Application to Broken Rotor Bars2014Konferensbidrag (Övrigt vetenskapligt)
  • 116.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Uncertainty Bounds Violation Scheme for FaultDetection in Induction Motors: Application to Broken Rotor Bars2014Konferensbidrag (Refereegranskat)
  • 117.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Kominiak, Dariusz
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    A Fault Detection Scheme Based on Minimum Uncertainty Bounds Violation for Broken Rotor Bars in Induction Motors2016Ingår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 48, s. 63-77Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, a novel method for broken bars fault detection in the case of three-phase induction motors and under different payloads will be presented and experimentally evaluated. In the presented approach, the cases of a partially or full broken rotor bars is being also considered, caused by: a) drilling 4mm and 8mm out of the $13$mm thickness of the same rotor bar, and b) fully drilled (13mm) one, two and three broken bars. The proposed fault detection method is based on the Set Membership Identification (SMI) technique and a novel proposed minimum boundary violation fault detection scheme, applied on the identified motor's parameters. The system identification procedure is being carried out on the simplified equivalent model of the induction motor, during the steady-state operation (non-fault case), while at the same time the proposed scheme is able to calculate on-line the corresponding safety bounds for the identified variables, based on a priori knowledge of the measuring corrupting noise (worst case encountered). The efficiency, the robustness and the overall performance of the established fault detection scheme is being extensively evaluated in multiple experimental studies and under various time instances of faults and load conditions.

  • 118.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Saied, Basil
    Department of Electrical Engineering, University of Mosul.
    Broken bar fault detection based on set membership identification for three phase induction motors2012Ingår i: Proccedings of the 9th International Conference on Informatics in Control, Automation and Robotics: Rome, Italy, 28-31, July, 2012, SciTePress, 2012, s. 224-231Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article presents a fault detection scheme for the case of a broken bar occurrence in a three phase induction motor. The proposed scheme relies on Set Membership Identification (SMI) and novel proposed boundary violation rules for the identified motor’s parameters. The model of the three phase induction motor is being transformed into an equivalent two phase model, described in the q−d space, for both the normal and the faulty case. By the utilization of the SMI technique, the simplified equivalent model of the induction motor is being identified during the steady state operation (non–fault case), while at the same time safety bounds for the identified variables are being provided, based on an a priori defined corrupting additive noise. On the event of a fault, specific fault detection conditions are being proposed that can capture the specific typeof a broken bar fault. The proposed conditions depend on: a) abnormal parameter jumps, and b) rapid changes in the volume of the bounding uncertainty, which is being formulated either by ellipsoids or orthotopes. Detailed analysis of the proposed approach as also extended simulation results are being presented that prove the efficiency of the proposed scheme.

  • 119.
    Mustafa, Mohammed Obaid
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Varagnolo, Damiano
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Detecting broken rotor bars in induction motors with model-based support vector classifiers2016Ingår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 52, s. 15-23Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a methodology for testing the sanity of motors when both healthy and faulty data are unavailable. More precisely, we consider a model-based Support Vector Classification (SVC) method for the detection of broken bars in three phase asynchronous motors at full load conditions, using features based on the spectral analysis of the stator's steady state current (more specifically, the amplitude of the lift sideband harmonic and the amplitude at fundamental frequency). We diverge from the mainstream focus on using SVCs trained from measured data, and instead derive a classifier that is constructed entirely using theoretical considerations. The advantage of this approach is that it does not need training steps (an expensive, time consuming and often practically infeasible task), i.e., operators are not required to have both healthy and faulty data from a system for checking it. We describe what are the theoretical properties and fundamental limitations of using model based SVC methodologies, provide conditions under which using SVC tests is statistically optimal, and present some experimental results to prove the effectiveness of the suggested scheme.

  • 120.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    A Full Error Dynamics Switching Modeling and Control Scheme for an Articulated Vehicle2015Ingår i: International Journal of Control, Automation and Systems, ISSN 1598-6446, E-ISSN 2005-4092, Vol. 13, nr 5, s. 1221-1232Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, a complete analysis towards the development of a switching modeling and control framework for an articulated vehicle, under the effect of varying slip angles will be presented. The established nonlinear kinematic model, of the nonholonomic articulated vehicle, will be transformed into an error dynamics model, which in the sequel will be linearized around multiple nominal slip angle cases. The proposed control architecture will consist of a switching control scheme, based on multiple model predictive controllers, for the articulated vehicle under varying slip angles. The controllers will be developed in order to improve the performance of the articulated vehicle's path tracking, while compensating the varying slippage effect. The current measured slip angle is being considered as the switching rule and a corresponding switching control scheme is being defined, being able to apply constraints on the states, the control signal and the output variables. Both the non-slip and slip models will be derived to highlight the significance of accounting for slips in path following control and their significant effect on deteriorating the performance of the overall control scheme when not considered. Multiple simulation results will be presented to prove the efficacy of the overall suggested scheme.

  • 121.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Effect of Kinematic Parameters on MPC based On-line Motion Planning for an Articulated Vehicle2015Ingår i: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 70, s. 16-24Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this article is to analyze the effect of kinematic parameters on a novel proposed on-line motion planning algorithm for an articulated vehicle based on Model Predictive Control. The kinematic parameters that are going to be investigated are the vehicle's velocity, the maximum allowable change in the articulated steering angle, the safety distance from the obstacles and the total number of obstacles in the operating arena. The proposed modified path planning algorithm for the articulated vehicle belongs to the family of Bug-Like algorithms and is able to take under consideration, the mechanical and physical constraints of the articulated vehicle, as well as its full kinematic model. During the on-line motion planning algorithm, the MPC controller controls the lateral motion of the vehicle, through the rate of the articulation angle, while driving it accurately and safely over the on-line formulated desired path. The efficiency of the proposed combined path planning and control scheme is being evaluated under numerous simulated test cases, while exhaustive simulations have been made for analyzing the dependency of the proposed framework on the kinematic parameters.

  • 122.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Kinematic modeling and simulation studies of a LHD vehicle under slip angles2011Ingår i: The IASTED International Conference on Modelling, Simulation and Identification, Pittsburgh, USA, ACTA Press, 2011, s. 344-349Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a kinematic model for a Load Haul Dumping Vehicle (LHD), with the ability to take under consideration the slipping angles is being derived. This specific type of vehicles consist of two parts, a steering tractor and a trailer, linked together with rigid free joint and can be found various applications, especially in the mine fields. In the rest of the article, exhaustive simulation studies are being provided for evaluating the performance of the model under multiple design and operational variables, such as: a) multiple parameters sets for slip angles, b) different steering angles, c) various wagons’ lengths, and d) various driving paths.

  • 123.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Online dynamic smooth path planning for an articulated vehicle2013Ingår i: 10th International Conference on Informatics in Control, Automation and Robotics, Reykjavik, Iceland, 29-31, July, 2013, 2013, Vol. 2, s. 177-183Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article proposes a novel online dynamic smooth path planning scheme based on a bug like modified path planning algorithm for an articulated vehicle under limited and sensory reconstructed surrounding static environment. In the general case collision avoidance techniques can be performed by altering the articulated steering angle to drive the front and rear parts of the articulated vehicle away from the obstacles. In the presented approach factors such as the real dynamics of the articulated vehicle, the initial and the goal configuration (displacement and orientation), minimum and total travel distance between the current and the goal points, and the geometry of the operational space are taken under consideration to calculate the update on the future way points for the articulated vehicle. In the sequel the produced path planning is being online and iteratively smoothen by the utilization of Bezier lines before producing the necessary rate of change for the vehicle’s articulated angle. The efficiency of the proposed scheme is being evaluated by multiple simulation studies.

  • 124.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    On-Line Path Planning for an Articulated Vehicle based on Model Predictive Control2013Ingår i: 2013 IEEE Multi-conference on Systems and Control (Conference on Control Applications), Hyderabad, India, August 28-30, 2013, 2013, s. 772-777Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article, a novel on–line path planning algorithm for an articulated vehicle, moving in a partially known and sensory based reconstructed environment, andrelying on Model Predictive Control will be presented. The proposed algorithm belongs to the family of bug like path planning algorithms and has the capability to take under consideration the real dynamics of the articulated vehicle.Based on: a) an a prior knowledge of the current and the goal points, and b) a partial sensory based awareness of the surrounding environment, the algorithm is able to tune online the articulated steering angle in order to drive the front and the rear parts of the vehicle from avoiding collision with obstacles, while converging to the goal point. The proposed path planning algorithm is able to produce on–line the next reference way-point, solving the local and sub-optimal problem, while in the sequel a Model Predictive Controller is being utilized forcreating the proper control signal, the rate of the articulated angle based on an error dynamics kinematic model of the vehicle. Multiple simulation results are being presented that prove the efficiency of the suggested scheme.

  • 125.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Path following for an articulated vehicle based on switching model predictive control under varying speeds and slip angles2012Ingår i: 17th-ETFA 2012 - IEEE International Conference on Emerging Technology & Factory Automation,: Krakow, Poland, Sep. 17-21, 2012, Piscataway, NJ: IEEE Communications Society, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article is focusing on the problem of path following for an articulated vehicle under varying velocities and slip conditions. The proposed control architecture consists of a switching control scheme based on multiple model predictive controllers, fine tuned for dealing with different operating speeds and slip angles. In the presented analysis for the non–holonomic articulated vehicle, the corresponding kinematic model is being transformed into an error dynamics model, which is linearized around multiple nominal slip angle cases and various operating speeds. The existence of the slipping and varying speed has a significant effect on the vehicle’s path following capability and can significantly deteriorate the performance of the overall control scheme. Based on the derived multiple dynamics modeling, the current slip and vehicle’s speed are being considered as the signal selector for the proposed switching model predictive control scheme. The efficacy of the proposed controller is being evaluated byan extended set of simulation results.

  • 126.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Path Planning With Obstacle Avoidance and Sliding Mode Control for An Articulated Vehicle.2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    A dynamic obstacle avoidance technique and control strategy to derive an articulated vehicle has been proposed. The strategy consists of two elements: a path planning and controller scheme to make the vehicle track a reference path. Potential field algorithm is exploited to generate a free collision on-line reference path in dynamic environments. The potential field is modified, by considering the nonlinear kinematic model, of the articulated vehicle. The proposed sliding mode controller is capable of making the vehicle move in minimum error displacement.

  • 127.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Real-Time Bug-LIke Dynamic Path Planning for an Articulated Vehicle2014Ingår i: Informatics in Control, Automation and Robotics, Switzerland: Springer International Publishing , 2014, s. 201-215Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    This article proposes a novel real time bug like algorithm for performing a dynamic smooth path planning scheme for an articulated vehicle under limited and sensory reconstructed surrounding static environment. In the general case, collision avoidance techniques can be performed by altering the articulated steering angle to drive the front and rear parts of the articulated vehicle away from the obstacles. In the presented approach factors such as the real dynamics of the articulated vehicle, the initial and the goal configuration (displacement and orientation), minimum and total travel distance between the current and the goal points, and the geometry of the operational space are taken under consideration to calculate the update on the future way points for the articulated vehicle. In the sequel the produced path planning is iteratively smoothed online by the utilization of Bezier lines before producing the necessary rate of change for the vehicle’s articulated angle. The efficiency of the proposed scheme is being evaluated by multiple simulation studies that simulate the movement of the articulated vehicle in open and constrained spaces with the existence of multiple obstacles.

  • 128.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Switching model predictive control for an articulated vehicle2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a switching model predictive control scheme for an articulated vehicle under varying slip angles is being presented. For the non–holonomic articulated vehicle, the non–linear kinematic model that is able to take under consideration the effect of the slip angles is extracted. This model is transformed into an error dynamics model, which in the sequence is linearized around multiple nominal slip angle regions. The existence of the slip angles has a significant effect on the vehicle’s path tracking capability and can significantly deteriorate the performance of the overall control scheme. Based on the derived multiple error dynamic models, the varying slip angle is being considered as the switching rule and a corresponding switching mode predictive control scheme is being designed.

  • 129.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Switching model predictive control for an articulated vehicle under varying slip angle2012Ingår i: 20th IEEE Mediterranean Conference on Control and Automation: Barcelona, Spain, July 3-6, 2012, Piscataway, NJ: IEEE Communications Society, 2012, s. 884-889Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a switching model predictive control scheme for an articulated vehicle under varying slip angles is being presented. For the non–holonomic articulated vehicle, the non–linear kinematic model that is able to take under consideration the effect of the slip angles is extracted. This model is transformed to an error dynamics model, which in the sequence is linearized around multiple nominal slip angle cases. The existence of the slip angles has a significant effect on the vehicle’s path tracking capability and can significantly deteriorate the performance of the overall control scheme. Based on the derived multiple error dynamic models, the varying slip angle is being considered as the switching rule and a corresponding switching mode predictive control scheme is being designed that it is also able to take under consideration: a) the constrains on the control signals and b) the state constraints. Multiple simulation results are being presented that prove the efficacy of the overall suggested scheme.

  • 130.
    Nayl, Thaker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Kominiak, Dariusz
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nyberg, Rickard
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Design and experimental evaluation of a novel sliding mode controller for an articulated vehicle2018Ingår i: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 103, s. 213-221Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents the design and experimental evaluation of a novel sliding mode control scheme, being applied to the case of an articulated vehicle. The proposed sliding mode controller is based on a novel continuous sliding surface, being introduced for reducing the chattering phenomenon, while achieving a better tracking performance and a fast minimization of the corresponding tracking error. The derivation of the sliding mode controller relies on the fully nonlinear kinematic model of the articulated vehicle, while the overall stability of the control scheme is proven based on the Lyapunov's stability condition. The performance of the established control scheme is being experimentally evaluated through multiple path tracking scenarios on a small scale and fully realistic articulated vehicle

  • 131.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Project: Mine Patrolling Rovers2011Övrigt (Övrig (populärvetenskap, debatt, mm))
  • 132.
    Nikolakopoulos, George
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Alexis, Kostas
    University of Patras, Department of Electrical and Computer Engineering.
    Switching networked attitude control of an unmanned quadrotor2013Ingår i: International Journal of Control, Automation and Systems, ISSN 1598-6446, E-ISSN 2005-4092, Vol. 11, nr 2, s. 389-397Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, a switching networked attitude controller for an unmanned quadrotor over a wireless sensor network is presented. To deal with the network induced time varying delays, the quadrotor is being modeled as a switching time varying linear system, while the applied switching output feedback control scheme, is calculated based on Linear Matrix Inequalities, and is able to guarantee the stability of the quadrotor under arbitrary changes in the time delays.

  • 133.
    Nikolakopoulos, George
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Andrikopoulos, Georgios
    University of Patras.
    Arvanitakis, John
    University of Patras.
    Manesis, Stamatis
    University of Patras.
    Dynamic analysis and cascade movement simulation of a pneumatic muscle actuator2011Ingår i: Proceedings of the IASTED International Conference on Modelling, Simulation and Identification, ACTA Press, 2011, s. 407-414Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this article is to present a dynamic analysis and a cascade movement simulation of a Pneumatic Muscle Actuator (PMA). PMAs are highly non–linear pneumatic actuators where their elongation are proportional to the interval pressure. Their non–linear characteristics and the property of the hysteresis are posing several difficulties in simulating these pneumatic actuators and to obtain a comprehension of the PMA’s physical movement. In this article a novel detailed modeling, based on hardware in the loop simulationstudies, capable to describe the dynamic characteristic of the PMA and a detailed simulation environment for studying the cascade movement of PMAs will be presented.

  • 134.
    Nikolakopoulos, George
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Dritsas, Leonidas
    University of Patras, Department of Electrical Engineering.
    Sayyaddelshad, Saleh
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Combined networked switching output feedback control with D-region stability for performance improvement2014Ingår i: International Journal of Control, ISSN 0020-7179, E-ISSN 1366-5820, Vol. 87, nr 6, s. 1172-1180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, a combined networked switching output feedback control scheme, with a (Formula presented.)-region stability performance improvement module is presented. The network induced time delays, that are considered to be time varying and integer multiples of the sampling period, are being embedded in the system model, by state augmentation. The resulting model of the overall networked closed-loop system is switching, with the current measured round-trip time delay acting as the switching rule. Based on this modelling approach, a Linear Matrix Inequality (LMI) tuned switching output feedback controller is designed. The proposed approach establishes robustness against time delays and is able to guarantee the overall stability of the switching closed-loop system. Integrated in the controlled synthesis phase, an LMI tuned performance improvement module is being introduced, based on (Formula presented.)-region stability. Multiple simulation results are being presented that prove the efficacy of the proposed scheme.

  • 135.
    Nikolakopoulos, George
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Martinsson, Pär-Erik
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system. ProcessIT Innovations.
    Andersson, Ulf
    Mine Tek HB, Kiruna.
    A Vision of Zero Entry Production Areas in Mines2015Ingår i: IFAC-PapersOnLine, E-ISSN 2405-8963, Vol. 48, nr 17, s. 66-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This industrial article aims in presenting a short roadmap on the identified activities and technologies needed towards the vision of zero entry production areas in Mines. This work has been performed in close cooperation with large mining companies in Europe as part of the Smart Mine of the Future Research, Development and Innovation Program and will present the most important areas that it is expected the robotic technology to have an impact on.

  • 136.
    Nikolakopoulos, George
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Mustafa, Mohammed Obaid
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Georgoulas, George
    Grekland.
    Project: Fault Detection in Bearings2013Övrigt (Övrig (populärvetenskap, debatt, mm))
  • 137.
    Nikolakopoulos, George
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Mustafa, Mohammed Obaid
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gustafsson, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Novikov, Evgeny
    Boliden, Sverige.
    Projekt: Feldetektering i elektriska maskiner2013Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    Syftet med projektet är att utveckla och experimentellt utvärdera nya algoritmer för att upptäcka och isolera fel i elmotorer.

  • 138.
    Nikolakopoulos, George
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Stavrou, Pavlos
    Department of Informatics and Telecommunications, University of Athens.
    Tsitsipis, Dimitris
    Department of Electrical and Computer Engineering, University of Patras.
    Kandris, Dionisis
    Department of Electronics, Technological Educational Institute of Athens.
    Tzes, Anthony
    Department of Electrical and Computer Engineering, University of Patras.
    Theocharis, Theocharis
    Department of Informatics and Telecommunications, University of Athens.
    A dual scheme for compression and restoration of sequentially transmitted images over wireless sensor networks2013Ingår i: Ad hoc networks, ISSN 1570-8705, E-ISSN 1570-8713, Vol. 11, nr 1, s. 410-426Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A dual scheme for the compression and restoration of sequentially transmitted images over Wireless Sensor Networks (WSN) is presented. These networks are characterized by low transmission rates, extended packet losses and limited power resources, factors that degrade the overall system performance. Especially in the cases of transmitting multimedia content, a considerable number of data packets are dropped, with a corresponding direct effect on the received image quality. For dealing with this loss of valuable information, various retransmission schemes have been proposed that act as quality of service modules. However, this approach increases energy consumption and inserts considerable time delays, due to the rise of the traffic load in the network. This article proposes a novel dual transmission scheme, targeting mainly the area of Multimedia WSNs (WMSN), that aims to decrease the overall traffic load introduced by the retransmission schemes, by performing image restoration for lost data packets, at the receiver side. The proposed novel dual scheme is based on: a) the Quad Tree Decomposition algorithm that is adopted for compressing the image data before transmission over the WSN, and b) the fast image inpainting algorithm for restoring the effect of the missing data packets. The overall proposed scheme has been applied inmultiple experimental studies that prove its efficacy.

  • 139.
    Nyberg, Rickard
    et al.
    Luleå tekniska universitet.
    Kominiak, Dariusz
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Experimental evaluation of a modied obstacle based potential field algorithm for an off-road mobile robot2014Konferensbidrag (Övrigt vetenskapligt)
  • 140.
    Nyberg, Rickard
    et al.
    Luleå tekniska universitet.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Kominiak, Dariusz
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Experimental Evaluation of a Modified Obstacle Based Potential Field Algorithm for an Off-Road Mobile Robot2014Ingår i: Proceedings of the 11th International Conference on Informatics in Control, Automation and Robotics: ICINCO 2014, Vienna, Austria 1 - 3 September 2014 / [ed] J. Felipe, SciTePress, 2014, Vol. 1, s. 626-633Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article presents an experimental evaluation of a modified obstacle based artificial potential field algorithm for an off-road mobile robot. The first contribution of the presented approach concerns the transformation of the artificial potential field method for the guidance of the vehicle and obstacle avoidance, in order to make it suitable for utilising a visual feedback. The visual feedback is relying on a depth image, provided by the low cost kinect sensor. The second contribution concerns the proposal of a novel scheme for the identification and perception of obstacles. Based on the proposed methodology, the vehicle is capable of categorising the obstacles based on their height in order to alter the calculated forces, for enabling a cognitive decision regarding their avoidance or the driving over them, by utilising the robot’s off road capabilities. The proposed scheme is highly suggested for off road robots, since in the normal cases, the existence of small rocks, branches, etc. can be accidentally identified as obstacles that could make the robot to avoid them or block its further movement. The performance of the proposed modified potential field algorithm has been experimentally applied and evaluated in multiple robotic exploration scenarios, where from the obtained results the efficiency and the advantages of such a modified scheme have been depicted.

  • 141.
    Röijezon, Ulrik
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa och rehabilitering.
    Faleij, Ragnar
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa och rehabilitering.
    Kravelis, Petros S.
    Laboratory of Knowledge and Intelligent Computing, Department of Computer Engineering, Technological Educational Institute of Epirus, Arta.
    Georgoulas, Georgios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    A new clinical test for sensorimotor function of the hand: development and preliminary validation2017Ingår i: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 18, nr 1, artikel-id 407Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background

    Sensorimotor disturbances of the hand such as altered neuromuscular control and reduced proprioception have been reported for various musculoskeletal disorders. This can have major impact on daily activities such as dressing, cooking and manual work, especially when involving high demands on precision and therefore needs to be considered in the assessment and rehabilitation of hand disorders. There is however a lack of feasible and accurate objective methods for the assessment of movement behavior, including proprioception tests, of the hand in the clinic today. The objective of this observational cross- sectional study was to develop and conduct preliminary validation testing of a new method for clinical assessment of movement sense of the wrist using a laser pointer and an automatic scoring system of test results.

    Methods

    Fifty physiotherapists performed a tracking task with a hand-held laser pointer by following a zig-zag pattern as accurately as possible. The task was performed with left and right hand in both left and right directions, with three trials for each hand movement. Each trial was video recorded and analysed with a specifically tailored image processing pipeline for automatic quantification of the test. The main outcome variable was Acuity, calculated as the percent of the time the laser dot was on the target line during the trial.

    Results

    The results showed a significantly better Acuity for the dominant compared to non-dominant hand. Participants with right hand pain within the last 12 months had a significantly reduced acuity (p < 0.05), and although not significant there was also a similar trend for reduced Acuity also for participants with left hand pain. Furthermore, there was a clear negative correlation between Acuity and Speed indicating a speed-accuracy trade off commonly found in manual tasks. The repeatability of the test showed acceptable intra class correlation (ICC2.1) values (0.68-0.81) and standard error of measurement values ranging between 5.0–6.3 for Acuity.

    Conclusions

    The initial results suggest that the test may be a valid and feasible test for assessment of the movement sense of the hand. Future research should include assessments on different patient groups and reliability evaluations over time and between testers.

  • 142.
    Röijezon, Ulrik
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa och rehabilitering.
    Prellwitz, Maria
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa och rehabilitering.
    Ahlmark, Daniel Innala
    van Deventer, Jan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Hyyppä, Kalevi
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    A haptic navigation aid for individuals with visual impairments: Indoor and outdoor feasibility evaluations of the LaserNavigator2019Ingår i: Journal of Visual Impairment & Blindness, ISSN 0145-482X, E-ISSN 1559-1476, Vol. 113, nr 2, s. 194-201Artikel i tidskrift (Refereegranskat)
  • 143.
    Small, Elias
    et al.
    Luleå University of Technology.
    Fresk, Emil
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Andrikopoulos, Georgios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Modelling and Control of a Tilt-Wing Unmanned Aerial Vehicle2016Ingår i: 24th Mediterranean Conference on Control and Automation: June 21-24, Athens, Greece, 2016, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 1254-1259, artikel-id 7536050Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a Tilt-Wing Unmanned Aerial Ve- hicle (TW-UAV) and the preliminary evaluation of its hovering characteristics in extended simulation studies are presented. In the beginning, an overview of the TW-UAV’s design properties are established, highlighting the novelties of the proposed structure and the overall merits. The TW-UAV’s design and structural properties are mathematically modeled and utilized for the synthesis of a cascaded P-PI and PID based control structure for the regulation of its hovering performance. In addition, extensive simulation trials are performed in order to evaluate the structure’s efficiency in controlling the TW-UAV’s attitude and position under various noise and disturbance scenarios.

  • 144.
    Tsitsipis, Dimitris
    et al.
    Department of Electrical and Computer Engineering, University of Patras.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Tzes, Anthony
    Department of Electrical and Computer Engineering, University of Patras.
    Koumpias, Stavros
    Department of Electrical and Computer Engineering, University of Patras.
    A dual scheme for secured multimedia wireless sensor network2011Ingår i: 19th Mediterranean Conference on Control and Automation, MED 2011, Piscataway, NJ: IEEE Communications Society, 2011, s. 1160-1165Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article a dual scheme for secured Multimedia Wireless Sensor Networks (MWSN) is being presented. The dual scheme is based on: a) the Quad Tree Decomposition algorithm that it is able to compress the images before transmission, while providing significant robustness in retaining the image quality, against packet losses, and b) the Secure and Scalable Rekeying Protocol (S2RP), which encrypts all the data transmissions and is also responsible for the rekeying process in case of a node failure. In the proposed MWSN, a trade off is being made among retaining secured and faster transmission rates against the quality of the transmitted images. Multiple experimental results are presented that prove the efficacy of the proposed scheme.

  • 145.
    Vachtsevanos, George
    et al.
    School of Electrical and Computer, Engineering, Georgia Institute of Technology, Atlanta.
    Georgoulas, Georgios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Fault Diagnosis, Failure Prognosis and Fault Tolerant Control of Aerospace/Unmanned Aerial Systems2016Ingår i: 24th Mediterranean Conference on Control and Automation (MED): June 21-24, Athens, Greece, 2016, Piscataway, NJ: IEEE Communications Society, 2016, s. 366-371, artikel-id 7536041Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fault-tolerant control and operation of complex unmanned and aircraft systems is an emerging technology intended to provide the designer and operator with flexibility, interoperability, sustainment and reliability under changing operational requirements or mission profiles. Moreover, it is intended to reconfigure online hardware and software to maintain the operational integrity of the system in the event of contingencies (fault/failure modes). This paper presents an hierarchical architecture that uses available sensor information, fault isolation, failure prognosis, system restructuring and controller reconfiguration. The fault tolerant control framework relies on prognostic information to reconfigure system components and preserve the operational integrity of the aircraft. The hierarchical structure starts at the lowest component level and migrates to the middle system/subsystem level ending with the final mission level. We illustrate the methodology using an electro-mechanical actuator (EMA).

  • 146.
    Wopereis, Han
    et al.
    Robotics and Mechatronics (RAM), University of Twente, Lichtenvoorde, 7131 TK, Netherlands.
    van de Ridder, L. W.
    University of Twente, Netherlands.
    Lankhorst, Tom J. W.
    University of Twente, Netherlands.
    Klooster, Lucian
    Mechanical Engineering, University of Twente, Enschede, 7514DN, Netherlands.
    Bukai, Evyatar
    University of Twente, Netherlands.
    Wuthier, David
    Mechanical engineering, Aalborg university Copenhagen, Copenhagen, 2450, Denmark.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Stramigioli, Stefano
    EWI, University of Twente, Enschede, 7500AE, Netherlands.
    Engelen, Johan B. C.
    Robotics and Mechatronics, University of Twente, Enschede, 7500AE, Netherlands.
    Fumagalli, Matteo
    Robotics, Vision and Machine Intelligence, Aalborg University, Copenhagen, 2450, Denmark.
    Multimodal Aerial Locomotion: An Approach to Active Tool Handling 10 Author2018Ingår i: IEEE robotics & automation magazine, ISSN 1070-9932, E-ISSN 1558-223X, Vol. 25, nr 4, s. 57-65, artikel-id 8491265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The research focus in aerial robotics is shifting from contactless inspection toward interaction and manipulation, with the number of potential applications rapidly increasing [1]. Eventually, aerial manipulators, i.e., unmanned aerial vehicles (UAVs) equipped with manipulators, will likely take on hazardous maintenance tasks now performed by humans. For this to happen, aerial manipulators must be able to perform all the different operations required in these maintenance routines.

  • 147. Wuthier, David
    et al.
    Kominiak, Dariusz
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Fresk, Emil
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    A Geometric Pulling Force Controller for Aerial Robotic Workers2017Ingår i: IFAC-PapersOnLine, ISSN 1045-0823, E-ISSN 1797-318X, Vol. 50, nr 1, s. 10287-10292Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this article is to establish a geometric, pulling force control scheme in order to enable the concept of Aerial Robotic Workers (ARWs), where the capabilities of the Unmanned Aerial Vehicles (UAVs) are enhanced by aerial manipulators in order to exert known pulling forces on the environment, with characteristic applications such as levers actuation, debris removal and safety assessments. The proposed novel approach consists of interfacing a cascaded position control scheme with a manipulation framework in such a way that the UAV, together with the manipulator are being controlled in a complete system The validity of the proposed scheme as well as the ability of the UAV to track a desired pulling force is validated through a real-world experiment.

  • 148.
    Wuthier, David
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Kominiak, Dariusz
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Kanellakis, Christoforos
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Andrikopoulos, Georgios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Fumagalli, Matteo
    Aalborg University.
    Schipper, G.
    University of Twente.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    On the Design, Modeling and Control of a Novel Compact Aerial Manipulator2016Ingår i: 24th Mediterranean Conference on Control and Automation, MED 2016, Piscataway, NJ: IEEE Communications Society, 2016, s. 665-670, artikel-id 7536029Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this article is to present a novel fourdegree-of-freedom aerial manipulator allowing a multirotorUnmanned Aerial Vehicle (UAV) to physically interact with theenvironment. The proposed design, named CARMA (CompactAeRial MAnipulator), is characterized by low disturbances onthe UAV flight dynamics, extended workspace (with regard toits retracted configuration) and fast dynamics (compared to theUAV dynamics). The dynamic model is formulated and a controlstructure consisting of an inverse kinematics algorithm and independentjoint position controllers is presented. Furthermore,the design specifications of the prototype are analyzed in detail,while experimental evaluations are conducted for the extractionof the manipulator’s workspace and the evaluation of system’stracking capabilities over pick-and-place trajectories. Finally,it is shown that the selected joint position sensors, combinedwith the derived inverse dynamic algorithm allow to determinethe wrenches exerted at the base, due to swift motions of thearm.

  • 149.
    Zachiotis, Georgios
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Andrikopoulos, Georgios
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Gornez, Randy
    Honda Research Institute of Japan Co. Ltd., Wako, Japan.
    Nakamura, Keisuke
    Honda Research Institute of Japan Co. Ltd., Wako, Japan.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    A Survey on the Application Trends of Home Service Robotics2018Ingår i: 2018 IEEE International Conference on Robotics and Biomimetics (ROBIO), IEEE, 2018, s. 1999-2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    The area of service robots has steadily gained interest over the years as an attempt for deploying robots to tackle problems faced in our everyday lives. In this article, a survey on the application areas of home service robots is presented. A collection of robotic appliances is selected to be introduced based on their application objective of being an active part in a home environment. The dominant application areas of robotic home service are identified and overviewed through the governing dipole of: a) consumer, and b) research. The functional capabilities of each robot are addressed from a design and specification point of view, in order to highlight their key enabling features and justify their inclusion to each application area.

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