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Publications (10 of 131) Show all publications
Jafari, H., Nikolakopoulos, G. & Gustafsson, T. (2019). Stabilization of an Inverted Pendulum via Human Brain Inspired Controller Design. In: : . Paper presented at IEEE-RAS International Conference on Humanoid Robots. IEEE
Open this publication in new window or tab >>Stabilization of an Inverted Pendulum via Human Brain Inspired Controller Design
2019 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
IEEE, 2019
National Category
Engineering and Technology
Identifiers
urn:nbn:se:ltu:diva-75901 (URN)
Conference
IEEE-RAS International Conference on Humanoid Robots
Available from: 2019-09-09 Created: 2019-09-09 Last updated: 2019-09-09
Mansouri, S. S., Kanellakis, C., Georgoulas, G., Kominiak, D., Gustafsson, T. & Nikolakopoulos, G. (2018). 2D visual area coverage and path planning coupled with camera footprints. Control Engineering Practice, 75, 1-16
Open this publication in new window or tab >>2D visual area coverage and path planning coupled with camera footprints
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2018 (English)In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 75, p. 1-16Article in journal (Refereed) Published
Abstract [en]

Unmanned Aerial Vehicles (UAVs) equipped with visual sensors are widely used in area coverage missions. Guaranteeing full coverage coupled with camera footprint is one of the most challenging tasks, thus, in the presented novel approach a coverage path planner for the inspection of 2D areas is established, a 3 Degree of Freedom (DoF) camera movement is considered and the shortest path from the taking off to the landing station is generated, while covering the target area. The proposed scheme requires a priori information about the boundaries of the target area and generates the paths in an offline process. The efficacy and the overall performance of the proposed method has been experimentally evaluated in multiple indoor inspection experiments with convex and non convex areas. Furthermore, the image streams collected during the coverage tasks were post-processed using image stitching for obtaining a single overview of the covered scene.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-68057 (URN)10.1016/j.conengprac.2018.03.011 (DOI)000433648100001 ()2-s2.0-85044107984 (Scopus ID)
Projects
Collaborative Aerial Robotic Workers, AEROWORKS
Funder
EU, Horizon 2020, 644128
Note

Validerad;2018;Nivå 2;2018-03-26 (andbra)

Available from: 2018-03-26 Created: 2018-03-26 Last updated: 2018-08-09Bibliographically approved
Alhashimi, A., Del Favero, S., Varagnolo, D., Gustafsson, T. & Pillonetto, G. (2018). Bayesian strategies for calibrating heteroskedastic static sensors with unknown model structures. In: 2018 European Control Conference (ECC): . Paper presented at European Control Conference, Cyprus, Limasson, 12-15 June, 2018 (pp. 2447-2453). Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>Bayesian strategies for calibrating heteroskedastic static sensors with unknown model structures
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2018 (English)In: 2018 European Control Conference (ECC), Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 2447-2453Conference paper, Published paper (Refereed)
Abstract [en]

This paper investigates the problem of calibrating sensors affected by (i) heteroskedastic measurement noise and (ii) a polynomial bias, describing a systematic distortion of the measured quantity. First, a set of increasingly complex statistical models for the measurement process was proposed. Then, for each model the authors design a Bayesian parameters estimation method handling heteroskedasticity and capable to exploit prior information about the model parameters. The Bayesian problem is solved using MCMC methods and reconstructing the unknown parameters posterior in sampled form. The authors then test the proposed techniques on a practically relevant case study, the calibration of Light Detection and Ranging (Lidar) sensor, and evaluate the different proposed procedures using both artificial and field data.

Place, publisher, year, edition, pages
Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2018
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-72550 (URN)10.23919/ECC.2018.8550201 (DOI)000467725302079 ()2-s2.0-85059819837 (Scopus ID)978-3-9524-2698-2 (ISBN)978-1-5386-5303-6 (ISBN)
Conference
European Control Conference, Cyprus, Limasson, 12-15 June, 2018
Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-06-18
Alhashimi, A., Pierobon, G., Varagnolo, D. & Gustafsson, T. (2018). Modeling and Calibrating Triangulation Lidars for Indoor Applications. In: Kurosh Madani, Dimitri Peaucelle, Oleg Gusikhin (Ed.), Kurosh Madani, Dimitri Peaucelle, Oleg Gusikhin (Ed.), Informatics in Control, Automation and Robotics: 13th International Conference, ICINCO 2016 Lisbon, Portugal, 29-31 July, 2016. Paper presented at 13th International Conference, ICINCO 2016 Lisbon, Portugal, 29-31 July, 2016 (pp. 342-366). Cham: Springer Publishing Company
Open this publication in new window or tab >>Modeling and Calibrating Triangulation Lidars for Indoor Applications
2018 (English)In: Informatics in Control, Automation and Robotics: 13th International Conference, ICINCO 2016 Lisbon, Portugal, 29-31 July, 2016 / [ed] Kurosh Madani, Dimitri Peaucelle, Oleg Gusikhin, Cham: Springer Publishing Company, 2018, p. 342-366Conference paper, Published paper (Refereed)
Abstract [en]

We present an improved statistical model of the measurement process of triangulation Light Detection and Rangings (Lidars) that takes into account bias and variance effects coming from two different sources of uncertainty:                                                                           {\$}{\$}(i) {\$}{\$}                 mechanical imperfections on the geometry and properties of their pinhole lens - CCD camera systems, and                                                                           {\$}{\$}(ii) {\$}{\$}                 inaccuracies in the measurement of the angular displacement of the sensor due to non ideal measurements from the internal encoder of the sensor. This model extends thus the one presented in [2] by adding this second source of errors. Besides proposing the statistical model, this chapter considers:                                                                           {\$}{\$}(i) {\$}{\$}                 specialized and dedicated model calibration algorithms that exploit Maximum Likelihood (ML)/Akaike Information Criterion (AIC) concepts and that use training datasets collected in a controlled setup, and                                                                           {\$}{\$}(ii) {\$}{\$}                 tailored statistical strategies that use the calibration results to statistically process the raw sensor measurements in non controlled but structured environments where there is a high chance for the sensor to be detecting objects with flat surfaces (e.g., walls). These newly proposed algorithms are thus specially designed and optimized for inferring precisely the angular orientation of the Lidar sensor with respect to the detected object, a feature that is beneficial especially for indoor navigation purposes.

Place, publisher, year, edition, pages
Cham: Springer Publishing Company, 2018
Series
Lecture Notes in Electrical Engineering, ISSN 1876-1100 ; 430
Keywords
Maximum likelihood, Least squares, Statistical inference, Distance mapping sensors, Lidar, Nonlinear system, AIC
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-66484 (URN)10.1007/978-3-319-55011-4_17 (DOI)978-3-319-55010-7 (ISBN)978-3-319-55011-4 (ISBN)
Conference
13th International Conference, ICINCO 2016 Lisbon, Portugal, 29-31 July, 2016
Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2019-10-08Bibliographically approved
Jafari, H., Pauelsen, M., Röijezon, U., Nyberg, L., Nikolakopoulos, G. & Gustafsson, T. (2018). On Internal Modeling of the Upright Postural Control in Elderly. In: : . Paper presented at 2018 IEEE International Conference on Robotics and Biomimetics (IEEE ROBIO 2018), December 12-15, 2018, Kuala Lumpur, Malaysia..
Open this publication in new window or tab >>On Internal Modeling of the Upright Postural Control in Elderly
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2018 (English)Conference paper, Published paper (Refereed)
National Category
Control Engineering Physiotherapy
Research subject
Control Engineering; Physiotherapy
Identifiers
urn:nbn:se:ltu:diva-72472 (URN)
Conference
2018 IEEE International Conference on Robotics and Biomimetics (IEEE ROBIO 2018), December 12-15, 2018, Kuala Lumpur, Malaysia.
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-09-26
Fresk, E., Nikolakopoulos, G. & Gustafsson, T. (2017). A Generalized Reduced-Complexity Inertial Navigation System for Unmanned Aerial Vehicles (ed.). IEEE Transactions on Control Systems Technology, 25(1), 192-207
Open this publication in new window or tab >>A Generalized Reduced-Complexity Inertial Navigation System for Unmanned Aerial Vehicles
2017 (English)In: IEEE Transactions on Control Systems Technology, ISSN 1063-6536, E-ISSN 1558-0865, Vol. 25, no 1, p. 192-207Article in journal (Refereed) Published
Abstract [en]

In this paper, a generic approach to attitude and position estimation, suited for any type of unmanned aerial vehicle, is presented. This will be achieved by establishing a generic framework, which can be extended using adaptive methods to determine the thrust properties of the engines and the mass of the aircraft, while keeping the overall computational complexity of the system low. Furthermore, the effect of magnetic disturbances will be reduced in a novel way by confining the magnetic errors to affect only heading, without compromising the pitch and roll estimation of the system with error-based estimation. The efficacy of the proposed framework will be evaluated through extended simulations and experimental validations on a multirotor. Finally, guidelines will be provided toward: 1) an implementation with a reduced computational complexity and 2) the utilization of the square-root formulations of the extended Kalman filter for extending the dynamic range of the filter.  

Place, publisher, year, edition, pages
IEEE, 2017
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-15975 (URN)10.1109/TCST.2016.2542022 (DOI)000391498700016 ()2-s2.0-84963657298 (Scopus ID)f8f7825a-d3c5-4ac9-9ccc-5fa1819c5264 (Local ID)f8f7825a-d3c5-4ac9-9ccc-5fa1819c5264 (Archive number)f8f7825a-d3c5-4ac9-9ccc-5fa1819c5264 (OAI)
Projects
Collaborative Aerial Robotic Workers, AEROWORKS
Funder
EU, Horizon 2020, 644128
Note

Validerad; 2017; Nivå 2; 2017-02-10 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-09-14Bibliographically approved
Atta, K., Johansson, A. & Gustafsson, T. (2017). Accuracy Improvement of Extremum Seeking Control. IEEE Transactions on Automatic Control, 62(4), 1952-1958, Article ID 7498657.
Open this publication in new window or tab >>Accuracy Improvement of Extremum Seeking Control
2017 (English)In: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 62, no 4, p. 1952-1958, article id 7498657Article in journal (Refereed) Published
Abstract [en]

In this work, we present a modification for theclassic and phasor extremum seeking control algorithms in orderto improve the accuracy by removing or reducing the convergenceerror. The modulation signals were replaced by a sum of sinusoidsin order to remove the equilibrium shift in the controlled variableof the averaged system. The convergence error is calculated as afunction of the number of sinusoids used in the modulation signal.A simulation example is presented to illustrate the improvement.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2017
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-62395 (URN)10.1109/TAC.2016.2584184 (DOI)000399033000031 ()2-s2.0-85018485239 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-03-29 (rokbeg)

Available from: 2017-03-10 Created: 2017-03-10 Last updated: 2018-07-10Bibliographically approved
Alhashimi, A., Varagnolo, D. & Gustafsson, T. (2017). Calibrating distance sensors for terrestrial applications without groundtruth information. IEEE Sensors Journal, 17(12), 3698-3709, Article ID 7911206.
Open this publication in new window or tab >>Calibrating distance sensors for terrestrial applications without groundtruth information
2017 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 17, no 12, p. 3698-3709, article id 7911206Article in journal (Refereed) Published
Abstract [en]

This paper describes a new calibration procedure for distance sensors that does not require independent sources of groundtruth information, i.e., that is not based on comparing the measurements from the uncalibrated sensor against measurements from a precise device assumed as the groundtruth. Alternatively, the procedure assumes that the uncalibrated distance sensor moves in space on a straight line in an environment with fixed targets, so that the intrinsic parameters of the statistical model of the sensor readings are calibrated without requiring tests in controlled environments, but rather in environments where the sensor follows linear movement and objects do not move. The proposed calibration procedure exploits an approximated expectation maximization scheme on top of two ingredients: an heteroscedastic statistical model describing the measurement process, and a simplified dynamical model describing the linear sensor movement. The procedure is designed to be capable of not just estimating the parameters of one generic distance sensor, but rather integrating the most common sensors in robotic applications, such as Lidars, odometers, and sonar rangers and learn the intrinsic parameters of all these sensors simultaneously. Tests in a controlled environment led to a reduction of the mean squared error of the measurements returned by a commercial triangulation Lidar by a factor between 3 and 6, comparable to the efficiency of other state-of-the art groundtruth-based calibration procedures. Adding odometric and ultrasonic information further improved the performance index of the overall distance estimation strategy by a factor of up to 1.2. Tests also show high robustness against violating the linear movements assumption.

Place, publisher, year, edition, pages
IEEE, 2017
Keywords
Calibration, Laser radar, Robot sensing systems, Mobile robots, Time measurement expectation maximization, distance sensors, intrinsic sensors calibration, heteroscedastic models, simultaneous sensors calibration, triangulation lidars, ultrasonic sensors, odometry
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-63189 (URN)10.1109/JSEN.2017.2697850 (DOI)000402123400012 ()2-s2.0-8502174995 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-05-29 (rokbeg)

Available from: 2017-04-28 Created: 2017-04-28 Last updated: 2019-08-27Bibliographically approved
Jafari, H., Castaño Arranz, M., Gustafsson, T. & Nikolakopoulos, G. (2017). On Control Structure Design for a Walking Beam Furnace. In: 2017 25th Mediterranean Conference on Control and Automation, MED 2017: . Paper presented at 25th Mediterranean Conference on Control and Automation, MED 2017, University of Malta, Valletta, Malta, 3-6 July 2017 (pp. 1355-1360). Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), Article ID 7984307.
Open this publication in new window or tab >>On Control Structure Design for a Walking Beam Furnace
2017 (English)In: 2017 25th Mediterranean Conference on Control and Automation, MED 2017, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 1355-1360, article id 7984307Conference paper, Published paper (Refereed)
Abstract [en]

The aim of this article is to introduce a novel sparse controller design for the temperature control of an experimental walking beam furnace in steel industry. Adequate tracking of temperature references is essential for the quality of the heated slabs. However, the design of the temperature control is hindered by the multivariable (non-square) dynamic behavior of the furnace. These dynamics include significant loop interactions and time delays. Furthermore, a novel data-driven model, based on real life experimental data that relies on a subspace state representation in a closed loop approach is introduced. In the sequel, the derived model is utilized to investigate the controller's structure. By applying the relative gain array approach a decentralized feedback controller is designed. However, in spite of the optimal and sparse design of the controller, there exists interaction between loops. By analyzing the interaction between the inputs-outputs with the Σ2 Gramian-based interaction methodology, a decoupled multi-variable controller is implied. The simulation result, based on the experimental modeling of the furnace, shows that the controller can successfully decrease the interaction between the loops and track the reference temperature set-points.

Place, publisher, year, edition, pages
Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017
Series
Mediterranean Conference on Control and Automation, ISSN 2325-369X
Keywords
Control Structure Design, Interaction Measures, Decentralized Control, Walking Beam Furnace
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-63041 (URN)10.1109/MED.2017.7984307 (DOI)000426926300222 ()2-s2.0-85027842203 (Scopus ID)978-1-5090-4533-4 (ISBN)
Conference
25th Mediterranean Conference on Control and Automation, MED 2017, University of Malta, Valletta, Malta, 3-6 July 2017
Projects
Integrated Process Control based on Distributed In-Situ Sensors into Raw Material and Energy Feedstock, DISIRE
Funder
EU, Horizon 2020, 636834
Available from: 2017-04-17 Created: 2017-04-17 Last updated: 2018-05-29Bibliographically approved
Mansouri, S. S., Georgoulas, G., Gustafsson, T. & Nikolakopoulos, G. (2017). On the covering of a polygonal region with fixed size rectangles with an application towards aerial inspection. In: 2017 25th Mediterranean Conference on Control and Automation, MED 2017: . Paper presented at 25th Mediterranean Conference on Control and Automation, MED 2017, University of Malta, Valletta, Malta, 3-6 July 2017 (pp. 1316-1320). Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), Article ID 7984300.
Open this publication in new window or tab >>On the covering of a polygonal region with fixed size rectangles with an application towards aerial inspection
2017 (English)In: 2017 25th Mediterranean Conference on Control and Automation, MED 2017, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 1316-1320, article id 7984300Conference paper, Published paper (Refereed)
Abstract [en]

Unmanned Aerial Vehicles (UAVs) equipped with remote visual sensing can be used in wide range of applications. However, guaranteeing the full coverage of the area and translating this coverage in a path planning problem, it is a quite challenging task. Thus, in this article a well-known and well-investigated family of hard optimization problems, covering a polygonal region (target area) with fixed size rectangles (camera frustrum), is studied. The problem is formulated mathematically and solved using metaheuristic optimization algorithms. The proposed novel algorithmic scheme requires an a priori 2D model of the target area, while it tries to maximize the coverage with a minimum number of fixed size rectangles. Finally, multiple simulation results are presented that prove the efficacy of the proposed scheme

Place, publisher, year, edition, pages
Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017
Series
Mediterranean Conference on Control and Automation, ISSN 2325-369X
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-65450 (URN)10.1109/MED.2017.7984284 (DOI)000426926300199 ()2-s2.0-85027893953 (Scopus ID)9781509045334 (ISBN)
Conference
25th Mediterranean Conference on Control and Automation, MED 2017, University of Malta, Valletta, Malta, 3-6 July 2017
Projects
Collaborative Aerial Robotic Workers, AEROWORKS
Funder
EU, Horizon 2020, 644128
Available from: 2017-09-01 Created: 2017-09-01 Last updated: 2018-05-29Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0079-9049

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