The potential field method and the nonlinear attractor dynamics approach: what are the differences?

One of the most popular approaches to path planning and control is the potential field method. This method is particularly attractive because it is suitable for on-line feedback control. In this approach the gradient of a potential field is used to generate the robot's trajectory. Thus, the path is generated by the transient solutions of a dynamical system. On the other hand, in the nonlinear attractor dynamic approach the path is generated by a sequence of attractor solutions. This way the transient solutions of the potential field method are replaced by a sequence of attractor solutions (i.e., asymptotically stable states) of a dynamical system. We discuss at a theoretical level some of the main differences of these two approaches

Nonlinear optimization for human-like movements of a high degree of freedom robotics arm-hand system

The design of autonomous robots, able to closely cooperate with human users in shared tasks, provides many new challenges for robotics research. Compared to industrial applications, robots working in human environments will need to have human-like abilities in their cognitive and motor behaviors. Here we present a model for generating trajectories of a high degree of freedom robotics arm-hand system that reflects optimality principles of human motor control. The process of finding a human-like trajectory among all possible solutions is formalized as a large-scale nonlinear optimization problem. We compare numerically three existing solvers, IPOPT, KNITRO and SNOPT, in terms of their real-time performance in different reach-to-grasp problems that are part of a human-robot interaction task. The results show that the SQP methods obtain better results than the IP methods. SNOPT finds optimal solutions for all tested problems in competitive computational times, thus being the one that best serves our purpose.Eliana Costa e Silva was supported by FCT (grant: SFRH/BD/23821/2005). The resources and equipment were financed by FCT and UM through project "Anthropomorphic robotic systems: control based on the processing principles of the human and other primates motor system and potential applications in service robotics and biomedical engineering" (Ref. CONC-REEQ/17/2001) and by EC through project "JAST: Joint-Action Science and Technology" (Ref. IST- 2-003747-IP).We thank the Mobile and Anthropomorphic Robotics Laboratory at University of Minho for constant good work environment. Finally, we would like to thank Carl Laird and Andreas Wachter for making available IPOPT, and AMPL for making available an unrestricted 30 days trial version of AMPL, KNITRO and SNOPT executables

Human-like movement of an anthropomorphic robot: problem revisited

Human-like movement is fundamental for natural human-robot interaction and collaboration. We have developed in a model for generating arm and hand movements an anthropomorphic robot. This model was inspired by the Posture-Based Motion-Planning Model of human reaching and grasping movements. In this paper we present some changes to the model we have proposed in [4] and test and compare different nonlinear constrained optimization techniques for solving the large-scale nonlinear constrained optimization problem that rises from the discretization of our time-continuous model. Furthermore, we test different time discretization steps.Eliana Costa e Silva was supported by FCT (grant: SFRH/BD/23821/2005)

Neuro-cognitive mechanisms of decision making in joint action: A human-robot interaction study

In this paper we present a model for action preparation and decision making in cooperative tasks that is inspired by recent experimental findings about the neurocognitive mechanisms supporting joint action in humans. It implements the coordination of actions and goals among the partners as a dynamic process that integrates contextual cues, shared task knowledge and predicted outcome of others’ motor behavior. The control architecture is formalized by a system of coupled dynamic neural fields representing a distributed network of local but connected neural populations. Different pools of neurons encode task-relevant information about action means, task goals and context in the form of self-sustained activation pat- terns. These patterns are triggered by input from connected populations and evolve continuously in time under the influence of recurrent interactions. The dynamic model of joint action is evaluated in a task in which a robot and a human jointly construct a toy object. We show that the highly context sensitive mapping from action observation onto appropriate complementary actions allows coping with dynamically changing joint action situations.The present research was conducted in the context of the fp6-IST2 EU-IP Project JAST (Project No. 003747) and partly financed by the FCT grants POCl/V.5/A0119/2005 and CONC-REEQ/17/2001. We would like to thank Profs. Harold Bekkering and Ruud Meulenbroek for the numerous discussions, and Emanuel Sousa, Flora Ferreira, Nzoji Hipolito, Rui Silva and Toni Machado for their help during the robotic experiments. We also thank the anonymous reviewers for their insightful comments and feedback on how to improve the manuscript

A dynamic field approach to goal inference, error detection and anticipatory action selection in human-robot collaboration

In this chapter we present results of our ongoing research on efficient and fluent human-robot collaboration that is heavily inspired by recent experimental findings about the neurocognitive mechanisms supporting joint action in humans. The robot control architecture implements the joint coordination of actions and goals as a dynamic process that integrates contextual cues, shared task knowledge and the predicted outcome of the user's motor behavior. The architecture is formalized as a coupled system of dynamic neural fields representing a distributed network of local but connected neural populations with specific functionalities. We validate the approach in a task in which a robot and a human user jointly construct a toy 'vehicle'. We show that the context-dependent mapping from action observation onto appropriate complementary actions allows the robot to cope with dynamically changing joint action situations. More specifically, the results illustrate crucial cognitive capacities for efficient and successful human-robot collaboration such as goal inference, error detection and anticipatory action selection.FCT grants POCI/V.5/A0119/2005 and CONC-REEQ/17/2001 / fp6-IST2 EU-IP Project JAST (proj. nr. 003747

Nonlinear optimization for human-like synchronous movements of a dual arm-hand robotic system

In previous work we have presented a model capable of generating human-like movements for a dual arm-hand robot involved in human-robot cooperative tasks. However, the focus was on the generation of reach-to-grasp and reach-to-regrasp bimanual movements and no synchrony in timing was taken into account. In this paper we extend the previous model in order to accomplish bimanual manipulation tasks by synchronously moving both arms and hands of an anthropomorphic robotic system. Specifically, the new extended model has been designed for two different tasks with different degrees of difficulty. Numerical results were obtained by the implementation of the IPOPT solver embedded in our MATLAB simulator

Generating human-like movements on an anthropomorphic robot using an interior point method

In previous work we have presented a model for generating human-like arm and hand movements on an anthropomorphic robot involved in human-robot collaboration tasks. This model was inspired by the Posture-Based Motion-Planning Model of human movements. Numerical results and simulations for reach-to-grasp movements with two different grip types have been presented previously. In this paper we extend our model in order to address the generation of more complex movement sequences which are challenged by scenarios cluttered with obstacles. The numerical results were obtained using the IPOPT solver, which was integrated in our MATLAB simulator of an anthropomorphic robot.EU funded Project PF7 Marie Curie ``NETT - Neural Engineering Transformative Technologies'', by FEDER funds through COMPETE (Operational Programme Thematic Factors of Competitiveness) and by portuguese funds through FCT (Foundation for Science and Technology) within the projects PEst-C/MAT/UI0013/2011 and FCOMP-01-0124-FEDER-022674

A inclusão da pessoa com deficiência física: um relato sobre o IFPA Campus Breves/ Person of inclusion with physical disabilities: a report on IFPA Campus Breves

 As estruturas das Escolas Públicas no município de Breves pouco apresentam espaços adequados para o aluno que possuem alguma deficiência física. Aos poucos, após algumas reformas as escolas vão inserindo adequações para a inserção das pessoas que tem deficiência física. Este artigo tem como objetivo apresentar a questão da acessibilidade de pessoas com deficiência física no Instituto Federal de Educação, Ciência e Tecnologia do Pará – IFPA Campus Breves, que possui um prédio recém construído com algumas adequações voltadas para a circulação dos deficientes físicos

DIFERENTES SUBSTRATOS E AMBIENTES PROTEGIDOS PARA O CRESCIMENTO DE MUDAS DE MARACUJAZEIRO AMARELO DOCE

A muda de alta qualidade, com vigor superior e equilíbrio de crescimento em altura e diâmetro, possui condições de melhor pegamento e sobrevivência no local definitivo de plantio. Objetivou-se estudar vários substratos contendo diferentes mistura de esterco bovino, solo de barranco, Bioplant®, vermiculita super fina e areia fina em ambientes telados na formação de mudas de maracujá. Foram utilizados o (A1) telado agrícola (dimensões: 8,0 m x 18,0 m x 3,5 m), fechamento em 45º de inclinação, com tela preta de monofilamento em toda sua extensão, malha para 50% de sombreamento (Sombrite®) e (A2) telado agrícola (dimensões: 8,0 m x 18,0 m x 4,0 m), com tela aluminizada termorrefletora na cobertura a 3,30 m, malha para 50% de sombreamento (Aluminet®), fechamentos laterais e frontais em 90º de inclinação com tela de monofilamento preta, malha para 50% de sombreamento. No interior dos ambientes protegidos, as mudas foram formadas em 13 substratos (S) oriundos das combinações (%) de esterco bovino (E), solo de barranco (S), Bioplant® (B), vermiculita super fina (F) e areia (A). Foram avaliadas a emergência, a altura, o diâmetro do colo e a relação entre a altura e o diâmetro.  As melhores mudas de maracujazeiro amarelo doce foram formadas em substratos com maiores quantidade de esterco e/ou vermiculita, com menores quantidades de areia e Bioplant®. Substratos com elevadas quantidades de Bioplant® ou areia não são indicados à formação de mudas de maracujazeiro. O telado aluminizado propiciou condições para obtenção de mudas de maior qualidade, com maior diâmetro em alguns substratos, e menor relação altura/diâmetro

Avaliação da influência da adição da cinza do bagaço da cana-de-açúcar na mitigação da reação álcali-agregado / Evaluation of the influence of the addition of sugarcane bagasse ash on the mitigation of the alkali-aggregate reaction

O objetivo deste trabalho é avaliar a influência da adição da cinza do bagaço da cana-de-açúcar (CBCA) em substituição parcial do cimento Portland na mitigação da reação álcali-agregado (RAA). A metodologia compreende na caracterização físico-química da CBCA, ensaio de petrografia do agregado reativo e a realização de ensaios laboratoriais em corpos-de-prova de barras de argamassas nos percentuais de substituição 0, 10, 20 e 25% do cimento Portland pela CBCA. De posse dos resultados, depreendeu-se que ocorreu uma mitigação da RAA para as argamassas produzidas com a CBCA. Conclui-se que o percentual de 25% de substituição atingiu o limite estabelecido por norma para a inibição total do RAA provando assim a eficácia da CBCA