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

Oleh:

Kuc, Roman

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: The International Journal of Robotics Research vol. 22 no. 2 (Feb. 2003), page 129-145.
Topik: acoustic flow; drive-by sensing; landmark recognition; object recognition; pattern classification; Polaroid transducer; robot navigation; sonar
Fulltext: 129.pdf (837.07KB)

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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 retroreflectors up to 7 m range were analyzed. Recognizing objects directly from echoes extends sonar sensing from data acquisition to landmark identification for robot navigation.

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