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arXiv 2021年

作者： Racković, Stevo Soares, Cláudia Jakovetić, Dušan Desnica, Zoranka Ljubobratović, Relja Institute for Systems and Robotics Instituto Superior Técnico Lisbon Portugal Computer Science Department NOVA School of Science and Technology Lisbon Portugal Department of Mathematics Faculty of Sciences UNS Novi Sad Serbia 3Lateral Epic Games Company

Digital human animation relies on high-quality 3D models of the human face—rigs. A face rig must be accurate and, at the same time, fast to compute. One of the most common rigging models is the blendshape model. We present a novel approach for learning the inverse rig parameters at increased accuracy and decreased computational cost at the same time. It is based on a two fold clustering of the blendshape face model. Our method focuses exclusively on the underlying space of deformation and produces clusters in both the mesh space and the controller space—something that was not investigated in previous literature. This segmentation finds intuitive and meaningful connections between groups of vertices on the face and deformation controls, and further these segments can be observed independently. A separate model for solving the inverse rig problem is then learnt for each segment. Our method is completely unsupervised and highly parallelizable. © 2021, CC BY-NC-SA.

关键词： Deformation

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Multi-agent systems with memories under DoS attacks

Multi-agent systems with memories under DoS attacks

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International Conference on Control, Automation, robotics and Vision (ICARCV)

作者： Ricardo Almeida Ewa Girejko Luís Machado Agnieszka B. Malinowska Natália Martins Department of Mathematics Center for Research and Development in Mathematics and Applications University of Aveiro Portugal Faculty of Computer Science Bialystok University of Technology Białystok Poland Institute of Systems and Robotics - University of Coimbra Coimbra Portugal Department of Mathematics University of Trás-os-Montes e Alto Douro (UTAD) Vila Real Portugal

ISBN: (纸本)9781665476881

The paper is devoted to multi-agent systems with memories under denial-of-service (DoS) attacks. The memory is represented by the fractional derivative that appears in the dynamics of the considered systems. The problem that we aim to address is, under which conditions the system continues to be stable or is in consensus mode, despite DoS attacks. Solutions to these problems are proposed in the presented theorems. We strengthen the theoretical considerations with numerical simulations.

关键词： Linear systems Sufficient conditions Automation Denial-of-service attack Numerical simulation Stability analysis Robots

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Better be reactive at the beginning. Implications of the first seconds of an encounter for the tutoring style in human-robot-interaction

Better be reactive at the beginning. Implications of the fir...

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IEEE International Symposium on Robot and Human Interactive Communication

作者： Karola Pitsch Katrin S. Lohan Katharina Rohlfing Joe Saunders Chrystopher L. Nehaniv Britta Wrede Applied Informatics Group and the Research Institute for Cognition and Robotics Faculty of Technology Bielefeld University Cognitive Humanoids Lab Istituto Italiano di Tecnologia for Robotics Brain & Cognitive Sciences Emergentist Semantics group at Bielefeld University Adaptive Systems Research Group School of Computer Science University of Hertfordshire

ISBN: (纸本)9781467346047

The paper investigates the effects of a robot's "on-line" feedback during a tutoring situation with a human tutor. Analysis is based on a study conducted with an iCub robot that autonomously generates its feedback (gaze, pointing gesture) based on the system's perception of the tutor's actions using the idea of reciprocity of actions. Sequential micro-analysis of two opposite cases reveals how the robot's behavior (responsive vs. non-responsive) pro-actively shapes the tutor's conduct and thus co-produces the way in which it is being tutored. A dialogic and a monologic tutoring style are distinguished. The first 20 seconds of an encounter are found to shape the user's perception and expectations of the system's competences and lead to a relatively stable tutoring style even if the robot's reactivity and appropriateness of feedback changes.

关键词： Coaching ENCOUNTERS Robot Feedback Human machine interaction REACTIVE cargo

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14th International Conference on Practical Applications of Computational Biology and Bioinformatics, PACBB 2020

作者： Pérez-Pérez, Martín Lourenço, Anália Igrejas, Gilberto Fdez-Riverola, Florentino ESEI Department of Computer Science University of Vigo Edificio Politécnico Campus Universitario as Lagoas s/n 32004 Ourense Spain CINBIO The Biomedical Research Centre University of Vigo Campus Univesitario Lagoas-Marcosende Vigo36310 Spain SING Next Generation Computer Systems Group Galicia Sur Health Research Institute SERGAS-UVIGO Vigo Spain CEB Centre of Biological Engineering University of Minho Campus de Gualtar Braga4710-057 Portugal Department of Genetics and Biotechnology University of Trás-os-Montes and Alto Douro Vila Real Portugal Functional Genomics and Proteomics Unit University of Trás-os-Montes and Alto Douro Vila Real Portugal LAQV-REQUIMTE Faculty of Science and Technology Nova University of Lisbon Lisbon Portugal

ISBN: (纸本)9783030545673

Concerning the field of Health sciences, one of the trends with the greatest impact today is related to the feeding and consumption of foods intended for chronic patients with a nutritional association. According to this, the gluten-free diet is one of the diets with a today’s fastest-growing due to their health therapy associations for different diseases and because of more and more people are freely choosing to follow a gluten-free diet. On this subject, e-commerce platforms are destined to be a key point for the sale of this kind of products due to: (i) the change in the business model caused by the electronic platforms and (ii) the expected increase consumption of disease designed special foods. For this reason, the experiences written by chronic disease patients and consumers in these platforms have become increasingly relevant. In this sense, the present work applies biomedical text mining methods and demographic knowledge inference techniques to a large number of gluten-free foods consumer’s experiences to discover a wide range of health-related topics associated to gluten-free products, alimentary social trends and demographics differences. The results of these analyses show significant trends over time;differences between males and females consumption and a wide range of health-related conclusions, such as: why consumers start a free gluten diet or what are the most discussed diseases and adverse reactions related to these products. © 2021, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Nutrition

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Discrete-time distributed Kalman filter design for multi-vehicle systems

Discrete-time distributed Kalman filter design for multi-veh...

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American Control Conference

作者： Daniel Viegas Pedro Batista Paulo Oliveira Carlos Silvestre Department of Electrical and Computer Engineering of the Faculty of Science and Technology of the University of Macau China Institute for Systems and Robotics (ISR) Instituto Superior Tecnico Universidade de Lisboa Portugal ISR and IDMEC Instituto Superior Tecnico Universidade de Lisboa Portugal

ISBN: (纸本)9781509045839

This paper addresses the problem of distributed state estimation in a multi-vehicle framework. In the scenario envisioned in this work, each vehicle aims to estimate its own state by implementing a local state observer which relies on locally available measurements and limited communication with other vehicles in the vicinity. The dynamics of the problem are formulated as a more general discrete-time Kalman filtering problem with a sparsity constraint on the gain and, based on this formulation, a method for computation of steady-state observer gains for arbitrary fixed measurement topologies is introduced. The proposed method consists in the optimization of the time-varying distributed Kalman filter over a finite time window to approximate steady-state behavior and compute well-performing steady-state observer gains. To assess the performance of the proposed solution, simulation results are detailed for the practical case of a formation of Autonomous Underwater Vehicles (AUVs).

关键词： discrete-time Kalman filters Observers State estimation Distribute vehicle filter design time windows Steady state Autonomous underwater vehicles space vehicle system Launching vehicle systems

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LiDAR-Based control of autonomous rotorcraft for the inspection of pier-like structures: Proofs

arXiv

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arXiv 2017年

作者： Guerreiro, Bruno J. Silvestre, Carlos Cunha, Rita Cabecinhas, David Institute for Systems and Robotics LARSyS Instituto Superior Técnico Universidade de Lisboa Av. Rovisco Pais 1 Lisboa1049 Department of Electrical and Computer Engineering Faculty of Science and Technology University of Macau Taipa Macau IST

This is a complementary document to the paper presented in [1], where more detailed proofs are provided for some results. The main paper addresses the problem of trajectory tracking control of autonomous rotorcraft in operation scenarios where only relative position measurements obtained from LiDAR sensors are possible. The proposed approach defines an alternative kinematic model, directly based on LiDAR measurements, and uses a trajectory-dependent error space to express the dynamic model of the vehicle. An LPV representation with piecewise affine dependence on the parameters is adopted to describe the error dynamics over a set of predefined operating regions, and a continuous-time H2 control problem is solved using LMIs and implemented within the scope of gain-scheduling control theory. In this document, Section A presents the stability analysis of the attitude inner-loop presented in [1, Section II.B], whereas Section B presents a more detailed version of the stability and performance guarantees for the LPV system, extending the results presented in [1, Section IV.A]. Copyright © 2017, The Authors. All rights reserved.

关键词： Continuous time systems

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Port-Hamiltonian Approach to Neural Network Training

Port-Hamiltonian Approach to Neural Network Training

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IEEE Annual Conference on Decision and Control

作者： Stefano Massaroli Michael Poli Federico Califano Angela Faragasso Jinkyoo Park Atsushi Yamashita Hajime Asama Department of Precision Engineering The University of Tokyo Tokyo Japan Department of Industrial and Systems Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon South Korea Faculty of Electrical Engineering Mathematics & Computer Science (EWI) Robotics and Mechatronics (RAM) University of Twente Enschede The Netherlands

ISBN: (数字)9781728113982

ISBN: (纸本)9781728113999

Neural networks are discrete entities: subdivided into discrete layers and parametrized by weights which are iteratively optimized via difference equations. Recent work proposes networks with layer outputs which are no longer quantized but are solutions of an ordinary differential equation (ODE);however, these networks are still optimized via discrete methods (e.g. gradient descent). In this paper, we explore a different direction: namely, we propose a novel framework for learning in which the parameters themselves are solutions of ODEs. By viewing the optimization process as the evolution of a port-Hamiltonian system, we can ensure convergence to a minimum of the objective function. Numerical experiments have been performed to show the validity and effectiveness of the proposed methods.

关键词： Training Biological neural networks Convergence Mathematical model Optimization Linear programming

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Optical fiber sensors for monitoring cement paste carbonation 5

Optical fiber sensors for monitoring cement paste carbonatio...

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5th International Conference on Applications of Optics and Photonics, AOP 2022

作者： Da Silva, P.M. Mendes, J.P. Coelho, L.C.C. De Almeida, J.M.M.M. INESC TEC-Institute for Systems and Computer Engineering Technology and Science Faculty of Sciences University of Porto Rua do Campo Alegre Porto4169-007 Portugal Department of Physics and Astronomy Faculty of Sciences University of Porto Rua do Campo Alegre Porto4169-007 Portugal CIQUP - Chemistry Research Unit Chemistry and Biochemistry Department Faculty of Sciences University of Porto Porto4169-007 Portugal Department of Physics School of Sciences and Technology University of Trás-os-Montes e Alto Douro Vila Real5001-801 Portugal

The use of concrete has been widespread in our society in housing and infrastructure, despite the environmental cost associated with its production. Its decay poses a social, economic, and environmental problem. Currently, the carbonation of cement paste is monitored through the measurement of its pH, with several optical fiber sensors (OFS) have been produced for this purpose. In the current work the focus is, also, on the carbonation monitoring of cement paste through an OFS, but not through pH measurements. Single fiber reflectance spectroscopy, previously employed to measure cement paste durability, is used to monitor the discoloration of cement paste caused by carbonation. As the carbonation front reaches the fiber tip embedded in the cement paste, the signal reflected onto the fiber increases. The accelerated carbonation of two limestone cement paste samples in an atmosphere of 100% CO2 was successfully monitored. The applicability of the sensor for operational use with ambient CO2 was confirmed through the measurement of carbonation at 3% CO2. The cross interference from water ingress and egress was also evaluated, and it didn't hinder the measurements of carbonation. Therefore, a novel OFS capable of measuring cement paste carbonation and durability, was achieved. © Published under licence by IOP Publishing Ltd.

关键词： Carbonation

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A discrete-time reputation-based resilient consensus algorithm for synchronous or asynchronous communications

arXiv

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arXiv 2021年

作者： Ramos, Guilherme Silvestre, Daniel Silvestre, Carlos The Department of Electrical and Computer Engineering Faculty of Engineering University of Porto Portugal NOVA University of Lisbon The Institute for Systems and Robotics Instituto Superior Técnico University of Lisbon Lisbon1049-001 Portugal The Dep. of Electrical and Computer Engineering The Faculty of Science and Technology The University of Macau China Instituto Superior Técnico Technical University of Lisbon Lisbon Portugal

We tackle the problem of a set of agents achieving resilient consensus in the presence of attacked agents. We present a discrete-time reputation-based consensus algorithm for synchronous and asynchronous networks by developing a local strategy where, at each time, each agent assigns a reputation (between zero and one) to each neighbor. The reputation is then used to weigh the neighbors' values in the update of its state. Under mild assumptions, we show that: (i) the proposed method converges exponentially to the consensus of the regular agents;(ii) if a regular agent identifies a neighbor as an attacked node, then it is indeed an attacked node;(iii) if the consensus value of the normal nodes differs from that of any of the attacked nodes' values, then the reputation that a regular agent assigns to the attacked neighbors goes to zero. Further, we extend our method to achieve resilience in the scenarios where there are noisy nodes, dynamic networks and stochastic node selection. Finally, we illustrate our algorithm with several examples, and we delineate some attacking scenarios that can be dealt by the current proposal but not by the state-of-the-art approaches. Copyright © 2021, The Authors. All rights reserved.

关键词： Stochastic systems

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Adaptive Backstepping of Synergistic Hybrid Feedbacks with Application to Obstacle Avoidance

Adaptive Backstepping of Synergistic Hybrid Feedbacks with A...

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American Control Conference

作者： Pedro Casau Ricardo G. Sanfelice Carlos Silvestre Institute for Systems and Robotics (ISR) Instituto Superior Técnico Universidade de Lisboa Lisboa Portugal University of California Santa Cruz CA 95064 USA Department of Electrical and Computer Engineering of the Faculty of Science and Technology of the University of Macau Macau China

ISBN: (纸本)9781538679012;9781538679265

In this paper, we show that the hybrid controller that is induced by a Synergistic Lyapunov Function and Feedback (SLFF) pair relative to a compact set, can be extended to the case where the original affine control system is subject to a class of additive disturbances known as matched uncertainties, provided that the estimator dynamics do not add new equilibria to the closed-loop system. We also show that the proposed adaptive hybrid controller is amenable to backstepping. Finally, we apply the proposed hybrid control strategy to the problem of global asymptotic stabilization of a compact set in the presence of an obstacle and we illustrate this application by means of simulation results.

关键词： Obstacle avoidance Backstepping Feedback Collision avoidance Liapunov function control systems Closed loop systems Self tuning Controllers

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