This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Saved Citations Download to citation manager Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kuc, R. Search for Related Content Social Bookmarking                   What's this?

Recognizing Retro-Reflectors with an Obliquely-Oriented Multi-Point Sonar and Acoustic Flow

Intelligent Sensors Laboratory Department of Electrical Engineering Yale University New Haven, CT 06520-8284, USA

This paper applies acoustic principles and a novel scanning method motivated by acoustic flow to recognize retro-reflectors directly from sonar echoes while performing drive-by scanning. Right-angle corners and cylinders form specular retro-reflectors that produce strong echoes whose features can be easily identified. A multi-point sonar produces a point process whose density encodes the echo amplitude and allows strong echoes to be isolated. In drive-by scanning an obliquely-oriented sonar beam passes over a retro-reflector which then exhibits a sequence of strong echoes having a pattern predicted by a forward model. Drive-by scans of a simple retro-reflector, a complex hallway environment and distant objects illustrate the method. An algorithm recognizes and localizes the retro-reflector by performing a two-dimensional search to find coordinates producing range readings matching the data in a weighted-least-squared error sense. A conventional Polaroid 6500 ranging module produced 5,000 sonar points in a drive-by scan of a hallway, which the algorithm converted into six corner locations. Interfering reflectors were detected by large deviations from the predicted template. Echoes from occluded retro-reflectors up to 7 m range were analyzed. Recognizing objects directly from echoes extends sonar sensing from data acquisition to landmark identification for robot navigation.

Key Words: acoustic flow • drive-by sensing • landmark recognition • object recognition • pattern classification • Polaroid transducer • robot navigation • sonar

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				W. Gao and M. Hinders Mobile Robot Sonar Backscatter Algorithm for Automatically Distinguishing Walls, Fences, and Hedges The International Journal of Robotics Research, February 1, 2006; 25(2): 135 - 145. [Abstract] [PDF]