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automatic detection of vehicles in outdoor parking lots from zenith perspective using neural networks

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Automatic detection of vehicles in outdoor parking lots from...

2020 Summer computer Simulation Conference, SCSC 2020, Held at the 2020 Summer Simulation Multi-Conference, SummerSim 2020

作者： García, Juan Manuel Carrera Piorno, Joaquín Recas Mata-Garcia, María Guijarro Department of Computer Architecture and Automatic Control Faculty of Computer Science Universidad Complutense de Madrid Spain

ISBN: (纸本)9781713819462

Nowadays there are a variety of methods to assist parking users in finding free sites in parking lots. However, there is no automatic system that takes into account the size of the car looking for a space or whether the cars adjacent to the free spaces are correctly parked. This paper presents a new method for detecting and calculating the area of vehicles in images taken from a zenith plane using computer vision and machine learning techniques that will help to create a vehicle-oriented search algorithm dedicated to finding the optimal spaces for vehicles entering an outdoor parking lot based on its characteristics. Results with scaled-down and real vehicles show that this new method can detect the area of the vehicles in an image with an average accuracy of 97.98%. ©2020 Society for Modeling & Simulation International (SCS)

关键词： Vehicles

Distributed formation maneuver control by manipulating the complex Laplacian

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arXiv 2020年

作者： de Marina, Hector Garcia Department of Computer Architecture Automatic Control Faculty of Physics Universidad Complutense Madrid Spain

This paper proposes a novel maneuvering technique for the complex-Laplacian-based formation control. We show how to modify the original weights that build the Laplacian such that a designed steady-state motion of the desired shape emerges from the local interactions among the agents. These collective motions can be exploited to solve problems such as the shaped consensus (the rendezvous with a particular shape), the enclosing of a target, or translations with controlled speed and heading to assist mobile robots in area coverage, escorting, and traveling missions, respectively. The designed steady-state collective motions correspond to rotations around the centroid, translations, and scalings of a reference shape. The proposed modification of the weights relocates one of the Laplacian's zero eigenvalues while preserving its associated eigenvector that constructs the desired shape. For example, such relocation on the imaginary or real axis induces rotational and scaling motions, respectively. We will show how to satisfy a sufficient condition to guarantee the global convergence to the desired shape and motions. Finally, we provide simulations and comparisons with other maneuvering techniques. Copyright © 2020, The Authors. All rights reserved.

关键词： Laplace transforms

Maneuvering and robustness issues in undirected displacement-consensus-based formation control

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arXiv 2020年

作者： de Marina, Hector Garcia Department of Computer Architecture and Automatic Control at the Faculty of Physics Universidad Complutense de Madrid Spain

n this paper, we first propose a novel maneuvering technique compatible with displacement-consensus-based formation controllers. We show that the formation can be translated with an arbitrary velocity by modifying the weights in the consensus Laplacian matrix. In fact, we demonstrate that the displacement-consensus-based formation control is a particular case of our more general method. We then uncover robustness issues with undesired steady-state motions and resultant distorted shapes in undirected displacement-consensus-based formation control. In particular, these issues are triggered when neighboring agents mismeasure their relative positions, e.g., their onboard sensors are misaligned and have different scale factors. We will show that if all the sensing is close to perfect but different among the agents, then the stability of the system is compromised. Explicit expressions for the eventual non-desired velocity and shape’s distortion are given as functions of the scale factors and misalignments for formations based on tree graphs. Copyright © 2020, The Authors. All rights reserved.

关键词： System stability

Securing isosceles triangular formations under heterogeneous sensing and mixed constraints

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arXiv 2021年

作者： Chan, Nelson P.K. Jayawardhana, Bayu de Marina, Hector Garcia Engineering and Technology Institute Groningen University of Groningen Nijenborgh 4 Groningen9747AG Netherlands Department of Computer Architecture and Automatic Control Faculty of Physics Universidad Complutense de Madrid Madrid28040 Spain

This paper focuses on securing a triangular shape (up to translation) for a team of three mobile robots that uses heterogeneous sensing mechanism. Based on the available local information, each robot employs the popular gradient-based control law to attain the assigned individual task(s). In the current work, robots are assigned either distance and signed area task(s) or bearing task(s). We provide a sufficient condition on the gain ratio RAd between the signed area and the distance control term such that the desired formation shape, an isosceles triangle, is reached from all feasible starting positions. Numerical simulations are provided to support the theoretical *** Codes 93D99 © 2021, CC BY-NC-SA.

关键词： Robots

Investigating the origin of optical flares from the TeV blazar S4 0954+65

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Astronomy and Astrophysics 2023年 679卷

作者： Pandey, Ashwani Bachev, Rumen Czerny, Bozena Wiita, Paul J. Gupta, Alok C. Strigachev, Anton Popowicz, Adam Center for Theoretical Physics Polish Academy of Sciences Al. Lotnikov 32/46 Warsaw02-668 Poland Institute of Astronomy and NAO Bulgarian Academy of Sciences 72 Tsarigradsko Shosse Blvd. Sofia1784 Bulgaria Department of Physics The College of New Jersey 2000 Pennington Road EwingNJ08628-0718 United States Manora Peak Nainital263001 India Faculty of Automatic Control Electronics and Computer Science Akademicka 16 Gliwice44-100 Poland

Aims. We aim to investigate the extreme variability properties of the TeV blazar S4 0954+65 using optical photometric and polarisation observations carried out between 2017 and 2023 using three ground-based telescopes. Methods. We examined an extensive dataset comprised of 138 intraday (observing duration shorter than a day) light curves (LCs) of S4 0954+65 for flux, spectral, and polarisation variations on diverse timescales. For the variable LCs, we computed the minimum variability timescales. We investigated flux-flux correlations and colour variations to look for spectral variations on long (several weeks to years) timescales. Additionally, we looked for connections between optical R-band flux and polarisation degree. Results. We found significant variations in 59 out of 138 intraday LCs. We detected a maximum change of 0.58 ± 0.11 in V-band magnitude within ∼2.64 h and a corresponding minimum variability timescale of 18.21 ± 4.87 mins on 2017 March 25. During the course of our observing campaign, the source brightness changed by ∼4 magnitudes in V and R bands;however, we did not find any strong spectral variations. The slope of the relative spectral energy distribution was 1.37 ± 0.04. The degree of polarisation varied from ∼3% to 39% during our monitoring. We observed a change of ∼120 degrees in polarisation angle (PA) within ∼3 h on 2022 April 13. No clear correlation was found between optical flux and the degree of polarisation. Conclusions. The results of our optical flux, colour, and polarisation study provide hints that turbulence in the relativistic jet could be responsible for the intraday optical variations in the blazar S4 0954+65. However, the long-term flux variations may be caused by changes in the Doppler factor. © 2023 EDP Sciences. All rights reserved.

关键词： Polarization

Singularity-free guiding vector field for robot navigation

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arXiv 2020年

作者： Yao, Weijia de Marina, Héctor Garcia Lin, Bohuan Cao, Ming University of Groningen Netherlands The Department of Computer Architecture and Automatic Control The Faculty of Physics Universidad Complutense de Madrid Madrid28040 Spain

In robot navigation tasks, such as UAV highway traffic monitoring, it is important for a mobile robot to follow a specified desired path. However, most of the existing path-following navigation algorithms cannot guarantee global convergence to desired paths or enable following self-intersected desired paths due to the existence of singular points where navigation algorithms return unreliable or even no solutions. One typical example arises in vector-field guided path-following (VF-PF) navigation algorithms. These algorithms are based on a vector field, and the singular points are exactly where the vector field diminishes. Conventional VF-PF algorithms generate a vector field of the same dimensions as those of the space where the desired path lives. In this paper, we show that it is mathematically impossible for conventional VF-PF algorithms to achieve global convergence to desired paths that are self-intersected or even just simple closed (precisely, homeomorphic to the unit circle). Motivated by this new impossibility result, we propose a novel method to transform self-intersected or simple closed desired paths to non-self-intersected and unbounded (precisely, homeomorphic to the real line) counterparts in a higher-dimensional space. Corresponding to this new desired path, we construct a singularity-free guiding vector field on a higher-dimensional space. The integral curves of this new guiding vector field is thus exploited to enable global convergence to the higher-dimensional desired path, and therefore the projection of the integral curves on a lower-dimensional subspace converge to the physical (lower-dimensional) desired path. Rigorous theoretical analysis is carried out for the theoretical results using dynamical systems theory. In addition, we show both by theoretical analysis and numerical simulations that our proposed method is an extension combining conventional VF-PF algorithms and trajectory tracking algorithms. Finally, to show the practical value of

关键词： Mobile robots

Distributed formation control for manipulator end-effectors

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arXiv 2021年

作者： Wu, Haiwen Jayawardhana, Bayu De Marina, Hector Garcia Xu, Dabo Engineering and Technology Institute Groningen Faculty of Science and Engineering University of Groningen Groningen9747 AG Netherlands Department of Computer Architecture and Automatic Control Faculty of Physics Universidad Complutense de Madrid Madrid28040 Spain School of Automation Nanjing University of Science and Technology Nanjing210094 China

We present three classes of distributed formation controllers for achieving and maintaining the 2D/3D formation shape of manipulator end-effectors to cope with different scenarios due to availability of modeling parameters. We firstly present a distributed formation controller for manipulators whose system parameters are perfectly known. The formation control objective is achieved by assigning virtual springs between end-effectors and by adding damping terms at joints, which provides a clear physical interpretation of the proposed solution. Subsequently, we extend it to the case where manipulator kinematic and system parameters are not exactly known. An extra integrator and an adaptive estimator are introduced for gravitational compensation and stabilization, respectively. Simulation results with planar manipulators and with seven degree-of-freedom humanoid manipulator arms are presented to illustrate the effectiveness of the proposed approach. Copyright © 2021, The Authors. All rights reserved.

关键词： Manipulators

Distributed formation control of manipulators' end-effector with internal model-based disturbance rejection

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arXiv 2021年

作者： Wu, Haiwen Jayawardhana, Bayu de Marina, Hector Garcia Xu, Dabo Engineering and Technology Institute Groningen Faculty of Science and Engineering University of Groningen Groningen9747 AG Netherlands Department of Computer Architecture and Automatic Control Faculty of Physics Universidad Complutense de Madrid Madrid28040 Spain The School of Automation Nanjing University of Science and Technology Nanjing210094 China

This paper addresses the problem of end-effector formation control for manipulators that are subjected to external disturbances: input disturbance torques and disturbance forces at each end-effector. The disturbances are assumed to be non-vanishing and are superposition of finite number of sinusoidal and step signals. The formation control objective is achieved by assigning virtual springs between end-effectors, by adding damping terms at joints, and by incorporating internal model-based dynamic compensators to counteract the effect of the disturbances;all of which presents a clear physical interpretation of the proposed approach. Simulation results are presented to illustrate the effectiveness of the proposed approach. © 2021, CC BY.

关键词： End effectors

Investigating the origin of optical flares from the TeV blazar S4 0954+65

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arXiv 2023年

作者： Pandey, Ashwani Bachev, Rumen Czerny, Bozena Wiita, Paul J. Gupta, Alok C. Strigachev, Anton Popowicz, Adam Center for Theoretical Physics Polish Academy of Sciences Al.Lotnikov 32/46 WarsawPL-02-668 Poland Institute of Astronomy and NAO Bulgarian Academy of Sciences Sofia1784 Bulgaria Department of Physics The College of New Jersey 2000 Pennington Road EwingNJ08628-0718 United States Manora Peak Nainital263001 India Faculty of Automatic Control Electronics and Computer Science Akademicka 16 Gliwice44-100 Poland

Aims. To investigate the extreme variability properties of the TeV blazar S4 0954+65 using optical photometric and polarization observations carried out between 2017–2023 using 3 ground-based telescopes. Methods. We examined an extensive dataset comprised of 138 intraday (observing duration shorter than a day) light curves (LCs) of S4 0954+65 for flux, spectral, and polarization variations on diverse timescales. For the variable LCs, we computed the minimum variability timescales. We investigated flux-flux correlations and colour variations to look for spectral variations on long-term (several weeks to years) timescales. Additionally, we looked for connections between optical R-band flux and polarization degree. Results. We found significant variations in 59 out of 138 intraday LCs. We detected a maximum change of 0.58±0.11 in V-band magnitude within ∼2.64 hr and a corresponding minimum variability timescale of 18.21±4.87 minutes on 2017 March 25. During the course of our observing campaign, the source brightness changed by ∼4 magnitudes in V and R bands;however, we did not find any strong spectral variations. The slope of the relative spectral energy distribution was 1.37±0.04. The degree of polarization varied from ∼ 3% to 39% during our monitoring. We observed a change of ∼120 degrees in polarization angle within ∼3 hr on 2022 April 13. No clear correlation was found between optical flux and the degree of polarization. Conclusions. The results of our optical flux, colour, and polarization study provide hints that turbulence in the relativistic jet could be responsible for the intraday optical variations in the blazar S4 0954+65. However, the long-term flux variations may be caused by changes in the Doppler factor. Copyright © 2023, The Authors. All rights reserved.

关键词： Polarization