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Matching Observed with Empirical Reality - What you see is what you get?

Kurbalija V., Ivanović M., von Bernstorff C., Nachtwei J., Burkhard H-D.

Fundamenta Informaticae

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2014

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Vol. 129, nr 1/2

133--147

EN

This paper outlines the primary steps to investigate if artificial agents can be considered as true substitutes of humans. Based on a Socially augmented microworld (SAM) human tracking behavior was analyzed using time series. SAM involves a team of navigators jointly steering a driving object along different virtual tracks containing obstacles and forks. Speed and deviances from track are logged, producing high-resolution time series of individual (training) and cooperative tracking behavior. In the current study 52 time series of individual tracking behavior on training tracks were clustered according to different similarity measures. Resulting clusters were used to predict cooperative tracking behavior in fork situations. Results showed that prediction was well for tracking behavior shown at the first and, moderately well at the third fork of the cooperative track: navigators switched from their trained to a different tracking style and then back to their trained behavior. This matches with earlier identified navigator types, which were identified on visual examination. Our findings on navigator types will serve as a basis for the development of artificial agents, which can be compared later to behavior of human navigators.

2

Agent Oriented Techniques for Programming Autonomous Robots

Burkhard H-D.

Fundamenta Informaticae

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2010

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Vol. 102, nr 1

49-62

EN

Robots and agents are both autonomously interacting with their environment. It is even argued that robots can be regarded as embodied agents. This paper discusses the use of Agent Oriented Techniques for controlling robots, their benefits and their limitations. Basic skills need much more emphasis for robots than related skills of agents. Algorithms for perception in the real world are a key problem for robot programming with many (still unsolved) challenges. More deliberative tasks like planning can benefit from techniques developed for agents. Since real environments are highly dynamic, classical planning techniques are not flexible enough, but there exist more sophisticated techniques for agents which are useful for robotics as well.

3

Constraint Based World Modeling

Göhring D, Mellmann H., Gerasymova K., Burkhard H-D.

Fundamenta Informaticae

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2008

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Vol. 85, nr 1-4

123-137

EN

Common approaches for robot navigation use Bayesian filters like particle filters, Kalman filters and their extended forms. We present an alternative and supplementing approach using constraint techniques based on spatial constraints between object positions. This yields several advantages. The robot can choose from a variety of belief functions, and the computational complexity is decreased by efficient algorithms. The paper investigates constraint propagation techniques under the special requirements of navigation tasks. Sensor data are noisy, but a lot of redundancies can be exploited to improve the quality of the result. We introduce two quality measures: The ambiguity measure for constraint sets defines the precision, while inconsistencies are measured by the inconsistency measure. The measures can be used for evaluating the available data and for computing best fitting hypothesis. A constraint propagation algorithm is presented.

4

Cooperative World Modeling in Dynamic Multi-Robot Environments

Göhring D, Burkhard H-D.

Fundamenta Informaticae

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2007

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Vol. 75, nr 1-4

281-294

EN

In this paper we describe how a group of agents can commonly estimate the position of objects. Furthermore we will show how these modeled object positions can be used for an improved self localization. Modeling of moving objects is commonly done by a single agent and in a robo-centric coordinate frame because this information is sufficient for most low level robot control and it is independent of the quality of the current robot localization. Especially when many robots cooperate with each other in a partially observable environment they have to share and to communicate information. For multiple robots to cooperate and share information, though, they need to agree on a global, allocentric frame of reference. But when transforming the egocentric object model into a global one, it inherits the localization error of the robot in addition to the error associated with the egocentric model. We propose using the relation of objects detected in camera images to other objects in the same camera image as a basis for estimating the position of the object in a global coordinate system. The spacial relation of objects with respect to stationary objects (e.g., landmarks) offers several advantages: The information is independent of robot localization and odometry and it can easily be communicated. We present experimental evidence that shows how two robots are able to infer the position of an object within a global frame of reference, even though they are not localized themselves. We will also show, how to use this object information for self localization. A third aspect of this work will cope with the communication delay, therefore we will show how the Hidden Markov Model can be extended for distributed object tracking.

5

Real Time Control for Autonomous Mobile Robots

Burkhard H-D.

Fundamenta Informaticae

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2002

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Vol. 51, nr 3

251-270

EN

Control of autonomous mobile robots in dynamical environments is interesting from a cognitive point of view as well as under application view points. Stimulus response controls are often favored for fast reactions to the environment. On the other hand, goals and plans are needed to guide long term behavior by deliberative control. Layered architectures are used for combination, but they inherit advantages as well as problems from both approaches. The paper proposes the Double Pass Architecture with hierarchically structured options/behaviors providing fast reactions on all levels.

6

Similarity and Distance in Case Based Reasoning

Burkhard H-D.

Fundamenta Informaticae

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2001

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Vol. 47, nr 3,4

201-215

EN

Notions of similarity and distance play an important role in informatics. Different disciplines have developed their own treatment of related measures. We consider this problem under the viewpoint of Case Based Reasoning. While distance and similarity can be considered to be formally equivalent, there exist some differences concerning their intuitive use which have impact to the composition of global measures from local ones.