Browsing by Subject "Mobile robotics"

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Open Access
Reliability measure assignment to sonar for robust target differentiation
(Elsevier, 2002) Ayrulu, B.; Barshan, B.
This article addresses the use of evidential reasoning and majority voting in multi-sensor decision making for target differentiation using sonar sensors. Classification of target primitives which constitute the basic building blocks of typical surfaces in uncluttered robot environments has been considered. Multiple sonar sensors placed at geographically different sensing sites make decisions about the target type based on their measurement patterns. Their decisions are combined to reach a group decision through Dempster-Shafer evidential reasoning and majority voting. The sensing nodes view the targets at different ranges and angles so that they have different degrees of reliability. Proper accounting for these different reliabilities has the potential to improve decision making compared to simple uniform treatment of the sensors. Consistency problems arising in majority voting are addressed with a view to achieving high classification performance. This is done by introducing preference ordering among the possible target types and assigning reliability measures (which essentially serve as weights) to each decision-making node based on the target range and azimuth estimates it makes and the belief values it assigns to possible target types. The results bring substantial improvement over evidential reasoning and simple majority voting by reducing the target misclassification rate. © 2002 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.
Open Access
The Universal robot bus : a local communication infrastructure for small robots
(2008-12) Avcı, Akın
Design and construction of small autonomous mobile robots is a challenging task that involves the selection, interfacing and programming of a large number of sensor and actuator components. Facilitating this tedious process requires modularity and extensibility in both hardware and software components. This thesis concerns the development of a real-time infrastructural architecture called the Universal Robot Bus (URB), based on the popular Inter-Integrated Circuit (I 2C) bus standard. The main purpose of the URB is the rapid development and realtime interfacing of local nodes controlling small sensor and actuator components distributed on a mobile robot platform. It is designed to be very lightweight and efficient, with real-time support for RS232 or USB connections to a central computer. The URB infrastructure is inspired from the RiSEBus architecture, which is also an internal communication protocol for mobile robots, and developed to fit our requirements. URB offers a modular and extensible architecture for rapid and frequent changes to the platform design. Mobile robots also need to perform accurate sensory processing and estimation in order to operate in unstructured environments. Hence, the URB also supports real-time operations with reliable hardware and software components. The first novel contribution of this thesis is the design and implementation of automatic synchronization of data acquisition across multiple nodes. Our synchronization algorithm ensures that each node completes data acquisition tasks simultaneously well before read operations. Our experiments also prove that each individual node acquires data at approximately the same time instant. The second major contribution of this thesis is the incorporation of automated and unsupervised data acquisition across multiple nodes into the URB protocol. Autonomous data acquisition helps acquire periodic and frequently needed data over nodes. This enhancement reduces the computational load on the central processing unit and reduces bandwidth costs over the communication medium. This thesis also servers a survey on network architectures and protocols, network applications in robotics, synchronization algorithms, and applications of synchronization in robotics besides implementation details of the URB.