Steuerungsarchitekturen für autonome mobile Roboter

This presents a new control architecture, which is designed to support the development of intelligent control systems. It is especially designed for systems that are connected to the real world via sensors and actuators and deal with dynamic and partly unpredictable environments, for instance to control an autonomous mobile robot. With quite an implementational effort, existing control-architectures allow to implement local or even global navigation facilities on a certain mobile robot. However, additional criteria that interfere with the navigational movements can usually not be added subsequently. Note that this situation occurs, e.g. if active sensing is requested, a handling device is added or other additional requirements arise. The purpose of the presented architecture is, first to allow easy implementation and second to obtain a modular control-system that displays a kind of superposition characteristic. Considering a typical behavior-based architecture, the focus is set on the method to coordinate the different mechanisms in order to obtain the desired over-all behavior of the system. The question is, how to combine commands or preferences of several running mechanisms. This work analyses several architecture with respect to the applied method of coordinating behaviors. The results of this analysis were used for the design of a new approach. The presented approach solves this merging-problem by using an utility-based approach. Each mechanisms continuously evaluates sensory data with respect to its special sub-task in order to rate all actions of a certain actuator. These ratings result in a utility function, that also includes the priority of the performed sub-task of the mechanism. A fusion-component, then merges these distribution for each actuator following a theorem of Keeny/Raiffa. Furthermore, we adopt virtual actuators with associated actuator mechanisms, which yields a hierarchical structure. Virtual actuators allow the designer to introduce more sophisticated actuators in addition to the physical actuators by specifying an actuator mechanism, which is responsible to execute the action and receives its priority by so called 'inheritation'. The resulting architecture combines reactive characteristics with determination. It was applied to control the autonomous mobile robot ARS. The robot displays a smooth, reactive but also goal-oriented behavior. It shows, that the employed fusion component really allows to compose the control-system as a superposition of very specialized, simple and therefore robust mechanisms. Furthermore, the resulting behavior shows to be a reasonable combination of the implemented sub-tasks. Here, prioritization is essential to provide a save method to inhibit bad actions with high priority, while simultaneously allowing tradeoffs among non-inhibited actions. Mechanisms can be implemented strictly task-oriented and thus kept simple. The special fusion-component allows to subsume actions, while also supporting tradeoffs and coordination of mechanisms. Priorities can be assigned to mechanisms or are estimated by an inheritation rule for actuator mechanisms. The superposition-characteristic keeps the system open for additional criteria to be met by the system. Conclusions: The work introduces a utility based control architecture using utility distributions, which allows to decompose the over-all control task into several simple, task-oriented, independent mechanisms. The architecture displays superposition characteristics and thus provides the option to extend the functionality of system, while keeping the implemented mechanisms unchanged. On the mobile robot ARS this architecture was implemented and applied to realize global navigation tasks in cluttered, real environments.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2002

Author dc:creator

• Stenzel, Roland

Contributors dc:contributor

• Spaniol, Otto

• info:eu-repo/classification/ddc/004
• Informatik

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-119118%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:57048