Title

Ultrasonic accurate sensor platform

College

College of Computer Studies

Department/Unit

Computer Technology

Document Type

Conference Proceeding

Source Title

12th Annual Conference on Mechatronics and Machine Vision in Practice, M2VIP 2005

First Page

54

Last Page

60

Publication Date

12-1-2005

Abstract

Ultrasonic sensors are popular devices to use for wheeled mobile-robot sensing requirements, to provide distance-to-object information. However limited resolution due to sensor beamwidth, incorrect ranging due to multiple reflections, and loss of echo due to specular reflections make the use of alternative sensor systems practically mandatory. This paper presents the implementation of a highperformance 2D sonar ranging system described by Heale and Kleeman in "Fast Target Classification Using Sonar". The system is implemented on PIC18F448 and PIC18F548 microcontrollers interfaced with a PC through the Extended Parallel Protocol (EPP). A DC motor is used to rotate a pair of Polaroid 7000 sensors 360 degrees around the vertical axis. Echoes received are digitized at a sampling rate in excess of 600KHz, are buffered then sent to the PC for processing. In this paper it is shown that despite uncontrolled chirp timing jitters in the transmitter circuitry of the transducer system, an alternative method of signal processing aside from that suggested by Kleeman is viable: tests show the ability of the system to range objects at distances from 0.30 meters up to 2.0 meters, with accuracy within three millimeters. The system is able to automatically identify planar as well as corner structures, with an allowable tilt and skew of 10 and 13 degrees respectively.

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