Ubirajara Moreno

Universidade Federal de Santa Catarina | UFSC · Departamento de Automação e Sistemas

The recent interest in the experience of the operator as an agent (“agency”) and the notable recent research activity in the interaction of this operator with robot swarms, referred as human–swarm interaction systems (HSI), brings new challenges and opens novel perspectives to interpret and counterbalance the difficulties that arise in highly autom...

Epidemiological models have a vital and consolidated role in aiding decision-making during crises such as the Coronavirus Disease 2019 (COVID-19) pandemic. However, the influence of social interactions in the spreading of communicable diseases is left aside from the main models in the literature. The main contribution of this work is the introducti...

In distributed and cooperative systems, the network structure is determinant to the success of the strategy adopted to solve complex tasks. Those systems are primarily governed by consensus protocols whose convergence is intrinsically dependent on the network topology. Most of the consensus algorithms deal with continuous values and perform average...

The focus of this paper is to present an algorithm that allows robotic teams to make decisions between a finite set of choices. The approach used was based on models that represent the way groups of humans evolve their opinions through time. Numerous works have explored models that consider the opinion as continuous values, while the literature les...

From the first Internet-based social networking applications designed to get people in contact and make friends to social networks made up of over 2 billion users, the combination of communication networks, portable devices, and AI has changed the way people interact and make decisions. The extent of this influence could be observed not only in mar...

The trend in human-controlled robotic systems is to move away from the current many-to-one paradigm, where multiple operators are forced to control a single system to a one-to-many mode of operation in which a single operator can control a large number of autonomous vehicles. For this transition to be successful, it is essential that we clearly und...

The increasing use of mobile cooperative robots in a variety of applications also implies an increasing research effort on cooperative strategies solutions, typically involving communications and control. For such research, simulation is a powerful tool to quickly test algorithms, allowing to do more exhaustive tests before implementation in a real...

Este trabalho apresenta uma abordagem para o desenvolvimento do pensamento inovador colaborativo na educação em engenharia no contexto da aprendizagem ativa. A metodologia tem uma arquitetura composta por princípios deĄnidos pela inovação, empatia, usabilidade, interdisciplinaridade, adaptabilidade, modularidade, integralidade e sustentabilidade....

Networks are the synthesised representation of interconnected systems that are in everywhere from protein collections in cells, flocks of birds, to complex iterations that govern the societies. The information spreading is the crucial point that makes these systems to work, so its control is vital to improve the system capabilities as a whole. Usin...

In multi-robot systems, it is commonly used collaborative approaches to solve complex tasks faster and efficiently. In most of those approaches, the decisions are made centralized or require global information about the objective or the robots, limiting many real implementations. The present work is based on a decentralized solution for the Rendezv...

Networked control systems pertain to a special class of sampled-data systems in which feedback control is performed over a communication network. When a communication network is shared among several systems, variable communication delay may occur, potentially affecting the control performance. Network restraints might be imposed as well, such as li...

In the Offshore Oil & Gas industry, particularly for Subsea Production Systems, the costs associated with downtime, maintenance intervention and repair of the equipment corresponds to a significant amount of the Operational Expenditure (OPEX). This drives the demand for more reliable equipment, embedded with technologies that enable a Condition-Bas...

Rendezvous is a common cooperative task for a team of mobile robots and is widely studied in the literature. The most recent studies suggest distributed approaches to this technique. So, this paper proposes a distributed technique for the robots to achieve rendezvous using the information of their positions even if they have a high level of uncerta...

Using a team of mobile robots connected through ad hoc networks is becoming increasingly attractive for a myriad of applications, including search, rescue and surveillance. In this paper, we present a method for the design and performance evaluation of complex wireless networked control systems, focusing on cooperative control strategy in robotic t...

When using multiple networked autonomous mobile robots to sense a given area online, it is of high importance to assure the network connectivity even when the robots move in the scope of their application target. In previous work, we have used a topological graph property known as bi-connectivity to turn the multi-robot network robust to dropout fa...

This paper proposes a novel design for the localization system of autonomous underwater vehicles (AUVs) using acoustic signals. The solution presented exploits models based on kernel functions with two main purposes: 1) to reject outliers; and 2) to correct or improve accuracy of measurements. The localization system discussed is based on well-esta...

Poster presenting part of the research with networked systems focused on adaptive control approaches that can detect communication links signal strength and change the network topology according to that. It was developed during the PhD exchange at Universidade do Porto, Portugal.

Purpose: To develop a categorization of complexity to the technological knowledge (TK) for the productive sector. Methodology: Characterizing technological development in function of the historical context, its complexity, interdisciplinarity, knowledge bases, and regulatory aspects of teaching. The categorization of the complexity of TK in the pro...

Moving in formation while tracking a reference trajectory is a common task for groups of mobile robots. In this work, we propose a solution which also deals with collision avoidance and communication topology preservation using Model Predictive Control (MPC) and the concept of virtual structure in a decentralized manner. We present results of simul...

In this work we present the integration between a robot cooperative control strategy and a wireless network simulated with OMNeT++. We use a consensus control strategy to carry out a rendez-vous task where information is shared among a group of robots. These robots are then simulated in a MANET environment with a TDMA-based protocol to minimize mes...

Differential kinematics is a traditional approach to linearize the mapping between the workspace and joint space. However, a Jacobian matrix cannot be inverted directly in redundant systems or in configurations where kinematic singularities occur. This work presents a novel approach to the solution of differential kinematics through the use of dual...

This work addresses the integration of a cooperative robot control strategy with a wireless network simulated with OMNeT++. We use a consensus control strategy in a rendez-vous task, which relies on sharing information among a group of robots simulated in a MANET environment. We consider WiFi ad-hoc technology with an overlay TDMA protocol, based o...

Maintaining connectivity in a multi-robot system is a complex task that depends on the communication topology. In this work, a method of topology control in mobile robot networks is presented. It uses consensus and model predictive control to adjust the robots positions in a decentralized and cooperative manner, creating a redundant communication g...

A Epistemologia do Conhecimento Tecnológico tem mecanismos de formação dos saberes da tecnologia que são atualmente pouco conhecidos. Uma questão filosófica bastante recorrente é: como se constrói este conhecimento e como este conhecimento pode promover a inovação? Este trabalho faz uma contextualização da formação do conhecimento tecnológico apres...

As ferramentas de apoio ao ensino de uma forma geral buscam o direcionamento das atividades de aprendizagem. Contudo, se a ferramenta não tiver elementos que potencializem a análise dos conteúdos, dificilmente haverá um aprendizado reflexivo. Neste trabalho é descrito uma metodologia para o desenvolvimento de ferramentas de ensino usando estratégia...

Resumo: Os conceitos de capacitância e capacitor são amplamente usados em diversas áreas do conhecimento, e mais especificamente nas Engenharias. Estes conceitos são resultados de trabalhos científicos na área de Engenharia de Materiais, e também da prática de projetos de sistemas que utilizam desses conceitos, como por exemplo a correção do Fator...

In multi-robot systems, communication is a critical factor to perform cooperative tasks. Maintain communication in a multi-robot systems is a complex task that is not feasible in certain conditions because the environmental interference or failures in the communication devices. This paper presents a topology control algorithm for maintaining connec...

This article discusses about the application of unmanned vehicles networks in several areas related to power systems. The main topics are related to the planning and mission control tools as well as coordination, communication and data sharing between the associated nodes. Throughout the work, some vehicles developed in the Underwater Systems and T...

In this paper, we assume that a set of non preemptive controller tasks should be implemented on a limited computational resource platform, and look for a sampling period assignment that allows to obtain the desirable performance. The problem is formulated as a multi-objective optimization problem under a resource constraint, where the cost function...

Modern networked control systems integrate multiple independent feedback control loops that require guaranteed bandwidth for timely operation. However, planning the distributed control systems considering worst-case requirements leads to expensive and inefficient designs. This motivated the development of dynamic rate adaptation as a technique to s...

The manipulation in singular regions promotes an instantaneous reduction in mechanism mobility, which can result in some disturbances in the trajectory tracking. The application of the quaternionic elements for motion representation not only guarantees an orthonormal transformation but also results in the smallest variance and minimizes the acceler...

The insertion of the communication network in feedback control loop makes the analysis and design of wireless networked control systems (WNCS) more complex, induces challenges in the form of: delays and packet losses, that degrade the control system's performance and even cause instability. From the viewpoint of application, the main challenge foun...

This article examines a strategy to establish are liable underwater acoustic communication for navigation of autonomous underwater vehicles (AUVs). This work proposes a framework through the use of kernel function based models to make the task of locating AUVs less sensitive to channel fluctuations. For this, the Auto-Associative Kernel Regression(...

This work presents a cooperation strategy for teams of multiple autonomous vehicles to solve the rendezvous problem. The approach is based on consensus algorithms, which are basically characterized by information exchange among the team members. The proposal is based on predictive control in order to compute decentralized control laws, considering...

A robust solution to the trajectory tracking control problem for a nonholonomic wheeled mobile robot should deal with the existence of structural and parameter uncertainties, external disturbances and operating limitations. The first order sliding control with boundary layer is a common and suitable solution that can ensure chattering attenuation,...

The manipulation in singular regions generates an instantaneous reduction in the mechanism mobility which can result in some disturbances in the trajectory tracking. In proximity of the singularities, small velocities in the end-effectors generates high speeds in the joints due to the gradual reduction of the mobility. The phenomenon of kinematic s...

The problem acoustic localization for autonomous underwater vehicles (AUVs) is discussed in the framework of kernel-based models. The approach consists of improving the measurement of time of fligth of acoustic signals with the help of the Auto-Associative Kernel Regression (AAKR). This makes localization less sensitive to perturbations in the acou...

We present a method for the synthesis of a full-order dynamic output-feedback compensator for time-stamped Networked Control Systems (NCS). The methodology is obtained from the use of a polytopic approximation for the NCS representation, based on the exact discretization of the originally linear time-invariant system. The dynamics of the proposed c...

The stabilization of a network controlled system including a global time-varying delay is investigated in this note. This delay is considered to be unknown but it is assumed that a bounded error estimate is available. The exponential uncertainty induced by the time-varying delay is decomposed into the sum of a polytopic term and an uncertain bounde...

This work presents a cooperation strategy for teams of multiple vehicles to solve the rendezvous problem. The approach is based on consensus algorithms, which are basically characterized by information exchange among the team members. The proposal is based on predictive control, in order to compute decentralized control laws, considering constraint...

The manipulation in singular regions promotes an instantaneous reduction in mechanism mobility, which can result in some disturbances in the trajectory tracking. In proximity to the singularities, small velocities of the end-effectors generate high speeds in the joints due to the gradual reduction of the mobility. The phenomenon of kinematic singul...

We propose a dynamic output-feedback compensator for time-stamped Networked Control Sys-tems (NCS). The design methodology is based on the use of a polytopic with additive norm-bounded represen-tation for the NCS. The dynamics of the proposed compensator depends on the delays induced by the network, which are supposed not to be greater than the sam...

This paper presents the results concerning the application of a backstepping based control law to urea-SCR (selective calalytic reduction) aftertreatment systems in diesel engines. The devised control law is applied over a reduced order model for the SCR catalyst, which is effective for closed-loop control and, besides that, can be embedded in dies...

This article addresses the problem of autonomous underwater vehicle navigation during operations in lakes of hydroelectric dam with respect to the acoustic positioning system. There are numerous challenges to the navigability of these vehicles, particularly the acoustic sensing system, used to locate them and obtain information about environmental...

The goal of this course is to present the topic of mobile robotics, including the design difficulties and challenges. Participants will be presented to the main design tools currently adopted. The topics to be addressed are: terrestrial mobile robots, unmanned aerial vehicles, submarine vehicles, architectures, movement control techniques, behavior...

This paper presents a method for synthesis of dynamic output-feedback controller partially de-pended on parameter for networked control systems. The results are described in terms of linear matrix inequal-ities based in a polytopic model for the system. Moreover, a restriction related with temporal performance for the closed-loop system is included...

In this paper, the performance of two nonlinear estimators is compared to deal with packet loss in Networked Control Systems (NCS). The evaluated nonlinear estimation methods are: Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF). In this article, it is shown that modifications are required in order to keep the convergence of the estim...

In this paper, a trajectory tracking control for a nonholonomic mobile robot subjected to kinematic disturbances is proposed. A variable structure controller based on the sliding mode theory is designed, and applied to compensate these disturbances. To minimize the problems found in practical implementations of the classical variable structure cont...

This paper presents the design and implementation of two Passivity-based controllers (PBC) to the problem of trajectory tracking of a robot manipulator with a parallel architecture, one called IDA-PBC (Interconnection and Damping Assignment) and the other called Power-Shaping. For the first controller is used the model system described as a Port-co...

Control systems through communication networks may have the performance impaired due to delays in the exchange of information between the components of the control system. In this article, closed-loop control and stability issues are treated, assuming as basic requirements some desired caracteristics about temporal behavior of the networked control...

In this paper, a trajectory tracking control for a nonholonomic mobile robot subjected to kinematic disturbances is proposed. A variable structure controller based on the sliding mode theory is used, and applied to compensate these disturbances. To minimize the problems found in practical implementations of the classical variable structure controll...

In this work a new perspective of a sucker-rod pumping system control is presented. The strategy consists in associating the bottom hole pressure measurement and dynamometer cards analysis in a cascaded control. In the proposal, the widely applied control strategies based on dynamometer cards are combined with the strategy based on the measurement...

This paper presents some results on the stabilization by a parameter dependent control law of a class of nonlinear discrete-time systems with some time-varying parameters and under control saturations. The studied control law consists of the feedback of both the states and of the nonlinearity present in the dynamics of the controlled system. Satura...

This paper presents some results on the stabilization by a parameter dependent control law of a class of nonlinear discrete-time systems with some time-varying parameters and under control saturations. The studied control law consists of the feedback of both the states and of the nonlinearity present in the dynamics of the controlled system. Satura...

This paper proposes the use of the relative dorsal position of a 5-link bipedal robot for a moment compensation that assures a stable walking, even if the robot parameters are not perfectly known. Furthermore, avoidance of knee hyperextension at the supporting leg is implemented, using a computed torque with modified PD control law in which the der...

In this work a new perspective of the control of a sucker-rod pumping system is presented. In despite of the widely application of control strategies based on dynamometer cards recognition they present several limitations in the control and maintenance aspects. Nowadays, with the development of a new class of low cost downhole sensors, new control...

This work proposes a new reference model fora control system functional architecture applied to open-architecture robot controller. Where, this proposal is applied for development of an five-layers based open-architecture robotic controller for interaction tasks, which uses parallel and distributed processing techniques, and avoids the necessity of...

Networked control systems (NCSs) are a very interesting solution to several control problems, and the definition of metrics and procedures for the design of more efficient NCSs is an open research field. This paper analyzes two evaluation metrics currently available: the quality-of-control and the jitter margin. This analysis will be used in furthe...

Based on mechanical energies analysis, the aim of this paper is to propose the use of the relative dorsal position of a 5-link bipedal robot in order to compensate its moments during the walking cycle, leading the previously unstable system to stability. Also, a modification of the PD control law avoids hyperextension at the supporting legpsilas kn...

In this paper the position control of robot manipulators considering joint flexibilities and friction compensation is presented. For the control purposes a cascade control strategy is presented and the friction compensation is described using the Generalized Maxwell-Slip (GMS) model. The GMS parameters are identified and a friction observer based o...

In a Networked Control System (NCS), the sampling period choice is crucial due largely to network resources constraints. The approximation of continuous-time controller, commonly used in related works, may not be a good option because it is sensitive to larger sampling time values. Additionally, the varying delay presented in this kind of control s...

The aim of this paper is to introduce a few topics about nonlinear systems that are usual in electrical engineering but are frequently disregarded in undergraduate courses. More precisely, the main subject of this paper is to present the analysis of bifurcations in dynamical systems through the use of symbolic computation. The necessary conditions...

In this paper, a co-design methodology for networked control systems (NCS), based on the feedback scheduling theory is proposed. In the proposed approach, the run-time information of the controlled process in employed to dynamically reassign the computational resources. The policy is to assign a lower bound of resources for each control loop for pl...

In a networked control system, it might be necessary to enlarge sampling intervals if an unexpected message needs to be sent through the network. However, it should be noted that to enlarge sampling periods cause closed loop instability. In this paper the jitter margin concept is used to establish a sufficient sampling period upper limit that ensur...

In this paper, a networked control systems (NCS) codesign methodology with remote controllers is proposed, based on the notion of jitter margin. The real-time systems theory applied to scheduling of messages in a network can be brought together with the concept of jitter margin to guarantee stability and control performance, even in the presence of...

In this paper a methodology to the analysis of bifurcations of variable structure systems is proposed. This methodology, based on the use of symbolic computation packages, is derived from the conditions of the existence of variable structure bifurcations of planar systems, allowing a multi-parametric analysis, without intensive numeric computations...

This paper presents some results on absolute stabilization of nonlinear discrete-time systems under control saturations. The studied control law consists of the feedback of both the states and of the nonlinearity present in the dynamics of the controlled system. Saturations are taken into account by modelling the nonlinear saturated system through...

In this paper, we propose a preliminary methodology, combining numerical and symbolic procedures, in order to analyze bifurcations in planar switching systems. This analysis is based on a classification of bifurcations of planar switching systems presented in this paper. The proposed methodology allows the analysis of the parameters influence in th...

This brief proposed applying the point transformation method of Andronov to analyze the different kinds of oscillation that may occur in piecewise-linear systems, of the first, second, and third order, when a relay with hysteresis is used in the feedback loop.

Variable structure systems are nonlinear because of the discontinuities introduced by switching. This brief analyzes local bifurcations directly related to the presence of a discontinuity surface and to the variation of its parameters. All types of bifurcations described in this brief are illustrated by an example from power electronics.

This paper is devoted to the analysis of a second order linear system with a piecewise linear feedback block exhibiting chaotic oscillations. The necessity of a feedback block which cannot be a function is pointed out. The analysis of the topological structure of the system is carried out by means of a point transformation method which allows one t...

This paper proposes the use of symbolic computation tools for the parametric analysis of the synchronization stability of chaotic oscillators. Moreover, some concepts of synchronization recently proposed in the literature are briefly presented

Symbolic computation can be used as an effective tool for the analysis of bifurcations in dynamical systems, allowing one to establish the relationship between the state variables and the parameters that play a crucial role in the occurrence of such phenomena without the need to perform extensive numerical calculations of every equilibrium conditio...

This paper addresses the problem of controlling a certain class of continuous-time nonlinear systems subject to actuator saturations. The design of state feedback gains is done by considering a modelling of the nonlinear saturated system through deadzone nonlinearities satisfying a modified sector condition, which encompasses the classical sector-n...