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2015


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Modeling interruption and resumption in a smartphone task: An ACT-R approach

Wirzberger, M., Russwinkel, N.

i-com, 14(2), Walter de Gruyter GmbH, 2015 (article)

Abstract
This research aims to inspect human cognition when being interrupted while performing a smartphone task with varying levels of mental demand. Due to its benefits especially in the early stages of interface development, a cognitive modeling approach is used. It applies the cognitive architecture ACT-R to shed light on task-related cognitive processing. The inspected task setting involves a shopping scenario, manipulating interruption via product advertisements and mental demands by the respective number of people shopping is done for. Model predictions are validated through a corresponding experimental setting with 62 human participants. Comparing model and human data in a defined set of performance-related parameters displays mixed results that indicate an acceptable fit – at least in some cases. Potential explanations for the observed differences are discussed at the end.

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DOI [BibTex]

2015


DOI [BibTex]


Exciting Engineered Passive Dynamics in a Bipedal Robot
Exciting Engineered Passive Dynamics in a Bipedal Robot

Renjewski, D., Spröwitz, A., Peekema, A., Jones, M., Hurst, J.

{IEEE Transactions on Robotics and Automation}, 31(5):1244-1251, IEEE, New York, NY, 2015 (article)

Abstract
A common approach in designing legged robots is to build fully actuated machines and control the machine dynamics entirely in soft- ware, carefully avoiding impacts and expending a lot of energy. However, these machines are outperformed by their human and animal counterparts. Animals achieve their impressive agility, efficiency, and robustness through a close integration of passive dynamics, implemented through mechanical components, and neural control. Robots can benefit from this same integrated approach, but a strong theoretical framework is required to design the passive dynamics of a machine and exploit them for control. For this framework, we use a bipedal spring–mass model, which has been shown to approximate the dynamics of human locomotion. This paper reports the first implementation of spring–mass walking on a bipedal robot. We present the use of template dynamics as a control objective exploiting the engineered passive spring–mass dynamics of the ATRIAS robot. The results highlight the benefits of combining passive dynamics with dynamics-based control and open up a library of spring–mass model-based control strategies for dynamic gait control of robots.

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link (url) DOI Project Page [BibTex]

link (url) DOI Project Page [BibTex]


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The optimism bias may support rational action

Lieder, F., Goel, S., Kwan, R., Griffiths, T. L.

NIPS 2015 Workshop on Bounded Optimality and Rational Metareasoning, 2015 (article)

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[BibTex]

[BibTex]


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Rational use of cognitive resources: Levels of analysis between the computational and the algorithmic

Griffiths, T. L., Lieder, F., Goodman, N. D.

Topics in Cognitive Science, 7(2):217-229, Wiley, 2015 (article)

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[BibTex]

[BibTex]


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Model-based strategy selection learning

Lieder, F., Griffiths, T. L.

The 2nd Multidisciplinary Conference on Reinforcement Learning and Decision Making, 2015 (article)

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Project Page [BibTex]

Project Page [BibTex]

2008


Learning to Move in Modular Robots using Central Pattern Generators and Online Optimization
Learning to Move in Modular Robots using Central Pattern Generators and Online Optimization

Spröwitz, A., Moeckel, R., Maye, J., Ijspeert, A. J.

The International Journal of Robotics Research, 27(3-4):423-443, 2008 (article)

Abstract
This article addresses the problem of how modular robotics systems, i.e. systems composed of multiple modules that can be configured into different robotic structures, can learn to locomote. In particular, we tackle the problems of online learning, that is, learning while moving, and the problem of dealing with unknown arbitrary robotic structures. We propose a framework for learning locomotion controllers based on two components: a central pattern generator (CPG) and a gradient-free optimization algorithm referred to as Powell's method. The CPG is implemented as a system of coupled nonlinear oscillators in our YaMoR modular robotic system, with one oscillator per module. The nonlinear oscillators are coupled together across modules using Bluetooth communication to obtain specific gaits, i.e. synchronized patterns of oscillations among modules. Online learning involves running the Powell optimization algorithm in parallel with the CPG model, with the speed of locomotion being the criterion to be optimized. Interesting aspects of the optimization include the fact that it is carried out online, the robots do not require stopping or resetting and it is fast. We present results showing the interesting properties of this framework for a modular robotic system. In particular, our CPG model can readily be implemented in a distributed system, it is computationally cheap, it exhibits limit cycle behavior (temporary perturbations are rapidly forgotten), it produces smooth trajectories even when control parameters are abruptly changed and it is robust against imperfect communication among modules. We also present results of learning to move with three different robot structures. Interesting locomotion modes are obtained after running the optimization for less than 60 minutes.

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link (url) DOI [BibTex]

2008


link (url) DOI [BibTex]

2005


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Bruder sein das ist nicht schwer, Schwester sein dagegen sehr?" - Geschlechtsspezifische Betrachtungsweisen zur Situation von Geschwistern behinderter Kinder und Jugendlicher

Wirzberger, M.

Protestant University of Applied Sciences, Bochum, 2005 (thesis)

Abstract
Die Diplomarbeit beschäftigt sich mit der Lebenssituation von Geschwistern behinderter Kinder und Jugendlicher und berücksichtigt hier besonders den Aspekt des Geschlechts. Nach einer Darstellung familiensoziologischer Grundlagen erläutert die Verfasserin den hohen Stellenwert von Geschwisterbeziehungen innerhalb der Familie, sowie deren Entwicklung und Veränderung im Laufe des Lebens. Der Schwerpunkt liegt dabei auf dem Kindes- und Jugendalter. Anschließend werden Grundlagen, Prozesse und Mechanismen geschlechtsspezifischer Sozialisation, und die Auswirkungen des Geschlechts auf die Geschwisterbeziehung thematisiert. Kapitel 3 beschäftigt sich zunächst mit dem Begriff der Behinderung mit Bezug auf das SGB IX und die ICF. Danach beschreibt die Verfasserin, mit welchen spezifischen Belastungen sich die Eltern behinderter Kinder und Jugendlicher konfrontiert sehen. Die Auswirkungen einer Behinderung auf die Geschwister stehen im Mittelpunkt dieser Arbeit und werden anhand von Studien von HACKENBERG und GROSSMAN, sowie Aussagen von ACHILLES ausführlich dargestellt, wobei auch hier der Aspekt des Geschlechts detailliert in die Schilderung der Situation einbezogen wird. Um eine Verbindung von Theorie und Praxis zu gewährleisten, werden zusammenfassende Hypothesen formuliert und anhand von drei Fallgeschichten exemplarisch überprüft. Abschließend erläutert die Verfasserin die Konsequenzen ihrer Diplomarbeit für die heilpädagogische Arbeit.

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DOI [BibTex]


Adaptation of Central Pattern Generators to Preexisting Mechanical Structure
Adaptation of Central Pattern Generators to Preexisting Mechanical Structure

Spröwitz, A.

Technische Universität Ilmenau, Ilmenau, 2005 (mastersthesis)

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[BibTex]

[BibTex]