CoopDynSim : a 3D robotics simulator

This paper presents CoopDynSim, a multi-robot 3D simulator. The main motivations for the development of a new simulation software lie in the need to emulate specific, custom made sensors, combined with the desire to smoothly transfer controller code from simulation to real implementation. The latter is achieved through the use of the same middleware layer already implemented in the real platforms. The high modularity of the solution allows the user to easily add new components or design new platforms. By having independent simulation threads for each robot, distributed control algorithms can easily be tested, abetted by a socket based connection, granting the possibility for an asynchronous, over the network, controller architecture. The ability to run simulations in real or simulated time, as well as a play back option, represent valuable features of the software. The simulator has been used in several projects, with different platforms and distinct control applications, proving it as a heterogeneous and flexible solution. Furthermore, its usage as a teaching tool in a robotics’ summer school as well as in an introductory robotics class in our university, upholds its simplicity and user-friendliness.Fundação para a Ciência e a Tecnologia (FCT) - ref. SFRH/BD/38885/200

Transporte de objectos por equipas de robôs móveis autónomos : implementação e validação de uma arquitectura de controlo distribuída, baseada em sistemas dinâmicos não lineares

Dissertação de Mestrado em Electrónica Industrial - Área de Especialização em Automação e RobóticaEsta dissertação tem como objectivo a implementação e validação de uma arquitectura de controlo, baseada em sistemas dinâmicos não lineares, para uma equipa de robôs móveis autónomos que em conjunto devem transportar um objecto de grandes dimensões desde uma posição inicial até uma posição de destino, e em simultâneo evitar colisões com obstáculos estáticos e/ou dinâmicos que possam encontrar no seu caminho. A arquitectura de controlo foi desenvolvida por um elemento do Grupo de Robótica Autónoma e Sistemas Dinâmicos, do departamento de Electrónica Industrial, da Universidade do Minho, no âmbito do seu doutoramento. Os robôs não têm qualquer conhecimento prévio do ambiente que os rodeia. A arquitectura de controlo é estruturada em termos de comportamentos elementares. Os comportamentos individuais e a sua integração são gerados por sistemas dinâmicos não lineares. Para a implementação da arquitectura de controlo foram utilizadas equipas de dois e de três robôs móveis autónomos, tendo sido os resultados documentados em vídeos. Estes resultados mostram o bom desempenho dos robôs em vários cenários, quer com obstáculos estáticos, quer com dinâmicos. O comportamento resultante é estável e as trajectórias são suaves, isto porque à medida que a informação sensorial e/ou comunicada varia, os sistemas dinâmicos adaptam-se, gerando soluções atractoras adequadas.The goal of this dissertation is the validation of a distributed control architecture, based on non-linear dynamical systems, for a team of autonomous mobile robots that jointly carry a large object from a starting position to a position of destination, and simultaneously avoid collisions with obstacles static and/or dynamic that can encounter in their path. The architecture was developed by an element from the Dynamical Systems and Autonomous Robotics Group of the Department of Industrial Electronics, from University of Minho, this work was carried out for his PhD. The robots have no prior knowledge whatsoever of the surrounding environment. The control architecture of each one of the robots is structured in terms of elemental behaviours. The individual behaviours and their integration are generated by non-linear dynamical systems. The implementation of the control architecture was performed on teams of two and three robots, the results were documented in video. These results show the good performance of robots in several environments, with static and/or dynamic ones. The resulting behaviour is stable and the trajectories are smooth, this is achieved because the dynamical systems adjust to changes in the information provided by the sensors and/or the information comunicated between the robots, generating adequate attractor solutions

Multi-robot cognitive formations

In this paper, we show how a team of autonomous mobile robots, which drive in formation, can be endowed with basic cognitive capabilities. The formation control relies on the leader-follower strategy, with three main pair-wise con-figurations: column, line and oblique. Furthermore, non-linear attractor dynamics are used to generate basic robotic behaviors (i.e. follow-the-leader and avoid obstacles). The control archi-tecture of each follower integrates a representation of the leader (target) direction, which supports leader detection, selection between multiple leaders (decision) and temporary estimation of leader direction (short-term memory during occlusion and prediction). Formalized as a dynamic neural field, this additional layer is smoothly integrated with the motor movement control system. Experiments conducted in our 3D simulation software, as well as results from the implementation in middle size robotic platforms, show the ability for the team to navigate, whilst keeping formation, through unknown and unstructured environments and is robust against ambiguous and temporarily absent sensory information.Fundação para a Ciência e a Tecnologia (FCT) - FCOMP-01-0124-FEDER-022674Fundos FEDER - Programa Operacional Fatores de Competitividade - COMPET

Object transportation by a human and a mobile manipulator : a dynamical systems approach

In this paper we address the problem of humanrobot joint transportation of large payloads. The human brings to the task knowledge on the goal destination and global path planning. The robot has no prior knowledge of the environment and must autonomously help the human, while simultaneously avoiding static and/or dynamic obstacles that it encounters. For this purpose a dynamic control architecture, formalized as a coupled system of non-linear differential equations, is designed to control the behavior of the mobile manipulator in close loop with the acquired sensorial information. Verbal communication is integrated that allows the robot to communicate its limitations. Results show the robot’s ability to generate stable, smooth and robust behavior in unstructured and dynamic environments. Furthermore, the robot is able to explain the difficulties it encounters and thus contribute to success of the task and to enhance the human-robot physical interaction.FP6-IST2-EU-project JAST (project no 003747)Portuguese Science and Technology Foundation (FCT) and FEDER project COOPDYN (POSI/SRI/38081/2001)

Using discrete simulation to support internal logistics process design

The objective of this paper is to present the developments of an ongoing project that aims at implementing an internal materials movement system using autonomous vehicles for supporting logistics processes. In particular the project focus on the movement of final products, from assembly lines to the expedition warehouse and the supply of packaging materials (customer packages), from the raw materials warehouse to the assembly lines. This process is currently carried out by two stackers, in a milk-run environment and, in the context of this project, an innovative solution is proposed to improve the performance of the supply and pickup processes, transforming and optimizing an entirely manual process into an automated one. The main challenge was to investigate the impact on the existing internal logistic system of the new solution and, simultaneously, to explore if new management strategies are needed to satisfy both throughput levels and overall supply chain needs. A simulation model was developed using ARENA Simulation Software to get insights concerning the new challenges posed by the solution to be adopted. Results have revealed that the use of simulation allowed the assessment of the impact of the new internal logistics solution and played a critical role to identify the best dispatching rules to schedule transportation orders in such a complex system. This research shows the flexibility of the simulation tool to address several complex management issues simultaneously that arises in the context of innovative solutions aligned with industry 4.0 challenges.This work has been financially supported by the Portugal Incentive System for Research and Technological Development in scope of the projects in co-promotion nº 002814/2015 (iFACTORY 20152018).info:eu-repo/semantics/publishedVersio

A software framework for the implementation of dynamic neural field control architectures for human-robot interaction

Useful and efficient human-robot interaction in joint tasks requires the design of a cognitive control architecture that endows robots with crucial cognitive and social capabilities such as intention recognition and complementary action selection. Herein, we present a software framework that eases the design and implementation of Dynamic Neural Field (DNF) cognitive architectures for human-robot joint tasks. We provide a graphical user interface to draw instances of the robot's control architecture. In addition, it allows to simulate, inspect and parametrize them in real-time. The framework eases parameter tuning by allowing changes on-the-fly and by connecting the cognitive architecture with simulated or real robots. Using the case study of an anthropomorphic robot providing assistance to a disabled person during a meal scenario, we illustrate the applicability of the framework.The work was funded by Project NETT: Neural Engineering Transformative Technologies, EU-FP7 ITN (nr.289146), and by FCT - Fundação para a Ciência e Tecnologia, through the Phd and Posdoc Grants (SFRH/BD/81334/2011 and SFRH/BPD/71874/2010 respectively, financed by POPH-QREN-Type 4.1- Advanced Training, co-funded by the European Social Fund and national funds from MEC), and Project Scope: UID/CEC/00319/2013 together with COMPETE: POCI-01-0145-FEDER007043.info:eu-repo/semantics/publishedVersio

A safe autonomous stacker in human shared workspaces

This paper proposes a solution for safe navigation of stacker vehicles in workspaces shared with people, with a focus on the docking manoeuvres for pallet picking and dropping. Behaviours for way-point and wall following are developed following the attractor dynamics approach. Then, these behaviours are orchestrated by state machines (that activate or deactivate them) depending on the specific task. Each of these states also defines different safe areas and maximum travel speeds, which is a requirement for safe operation. Results of real experiments are presented that show the standard operation and its robustness against perturbations (people in the way) and failure detection (missing pallets).Fundação para a Ciência e Tecnologia (FCT) within the R&D Units Project Scope: UIDB/00319/202

Revista de Administração, n. 7

Revista disponível em arquivo completo

Motion control for autonomous tugger vehicles in dynamic factory floors shared with human operators

We present a motion controller that generates collision free trajectories for autonomous Tugger vehicles operating in dynamic factory environments, where human operators may coexist. The controller is formalized as a dynamic system of path velocity and heading direction, whose vector fields change as sensory information varies. By design the parameters are tuned so that the control variables are close to an attractor of the resultant dynamics most of the time. This contributes to the overall asymptotically stability of the system and makes it robust against perturbations. We present several experiments, in a real factory environment, that highlight different innovative features of the navigation system - flexible and safe solutions for human-aware autonomous navigation in dynamic and cluttered environments. This means, besides generating online collision free trajectories between via points, the system detects the presence of humans, interact with them showing awareness of their presence, and generate adequate motor behavior.This work has been supported by National Funds through FCT -Fundacao para a Ciencia e Tecnologia within the Project Scope: UID/CEC/00319/2019, and by European Structural and Investment Funds in the FEDER component, through the Operational Competitiveness and Internationalization Programme (COMPETE 2020) [Project n degrees 002814; Funding Reference: POCI-01-0247-FEDER-002814]

Qualidade das águas drenadas dos quadros de arroz irrigado durante o estabelecimento do cultivo no sistema pré-germinado

Irrigated rice (Oriza sativa L.) pre-germinated production systems occupy approximately 100 thousand ha, annually cultivated in Rio Grande do Sul State, mainly in poorly drained areas, and with infestation of competing plants, especially red rice (Oriza sativa L.). This system constitutes the main technologic resource for rice crops produced on an ecological basis, by means of soil tillage and water management. Despite this, water outlets, specifically after seeding, have outstanding agronomic and environmental implications. Loss of nutrients and the physical and chemical quality of drained water have been questioned by public research and environmental institutions. This work evaluated the effects of different soil tillage systems and retention time of water in irrigated rice frames. The experiment was conducted in Viamão town, Rio Grande do Sul State. Two different soil tillage systems and four different times of frame drainage after seeding were investigated. Results showed that the main limiting attributes of water quality were turbidity, biochemical oxygen demand (BOD) and phosphorus (P) content, reaching 1800 TNU, 115 mg L-1 , and 1.6 mg L-1 , respectively. These attributes showed values higher than established environmental thresholds. Water quality was inappropriate to discharge directly into water courses, regardless of treatments.An alternative is the immediate placement in rice production areas, in more advanced development stages of plants. Pre-germinated rice crops require a system framework to avoid nutrient loss and consequent reduction of soil fertility.Os sistemas de produções de arroz (Oryza sativa L.) irrigado, pré-germinado ocupam uma superfície de aproximadamente 100 mil hectares, cultivados anualmente no Estado do Rio Grande do Sul, principalmente em áreas com deficiência de drenagem e com infestação de plantas competidoras, fundamentalmente o arroz vermelho (Oryza sativa L.). Esse sistema constitui a principal tecnologia para o cultivo de arroz de base ecológica, através do preparo do solo e do manejo da água nos quadros cultivados. Não obstante, a retirada da água dos quadros, especificamente após semeadura, tem implicações agronômicas e ambientais de destaque. A perda de nutrientes e a qualidade física e química da água drenada têm sido questionadas por instituições públicas, ambientais e de pesquisa. O objetivo desse trabalho foi avaliar os efeitos de diferentes formas de preparo do solo, assim como o tempo de permanência da água nos quadros de arroz irrigado pré-germinado. O experimento foi conduzido no município de Viamão – RS. Foram utilizados dois tipos de implementos para preparo do solo, associados a quatro tempos de drenagem dos quadros após a semeadura. Os resultados indicaram que os atributos mais limitantes em relação à qualidade da água, foram a turbidez, a demanda bioquímica de oxigênio (DBO) e os teores de fósforo, que chegaram a 1800 UNT, 115 mg L-1 e 1,6 mg L-1 , respectivamente. A turbidez, assim como as concentrações de P e DBO, apresentaram-se superiores ao limite legal em todos os tratamentos avaliados. Devido o envolvimento da água no preparo do solo, sua qualidade foi imprópria para o descarte diretamente nos cursos hídricos, independentemente do implemento utilizado e dos diferentes períodos de decantação avaliados. Dessa forma, uma alternativa é a utilização dessas águas imediatamente em áreas de produção com arroz em estágios mais avançados de desenvolvimento. As lavouras de arroz pré-germinado, sobretudo nas produções de base ecológica, demandam uma adequação do sistema ao estabelecido pela legislação, contribuindo também para evitar perdas de nutrientes e a consequente redução da fertilidade dos solos