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Position Control Technique of Ultrasonic Scanner for an Automated Ultrasonic Testing Using Surface Wave  

Lee, Jong-Po (Korea Advanced Inspection Technology, Inc.)
Park, Chul-Hoon (Korea Advanced Inspection Technology, Inc.)
Um, Byong-Guk (Korea Advanced Inspection Technology, Inc.)
Publication Information
Journal of the Korean Society for Nondestructive Testing / v.23, no.1, 2003 , pp. 30-37 More about this Journal
Abstract
In order to replace the manual ultrasonic testing(UT) with an automated UT(AUT), a scanner which enables us to control the positions of a transducer is essential. Encoders have been commonly used to obtain the position information from the conventional scanners controlled by motor. Encoders have various advantages in many aspects. However, if the slip of motor wheel occurs during scanning, various errors are involved in the position accuracy. Thus, the position information of encoders becomes meaningless in case of slip. The reliability of AUT results nay become serious problem. Hence, slip must be avoided, but it can not be completely avoided at present time. In this paper, a new idea that surface wave is used to solve this problem and replace encoders has been proposed. It is shown that this idea can be employed in AUT scanner without encoders. That is, one transducer transmitting surface wave is fixed and the other transducer attached to the scanner receives UT signal. Then, computer calculates the present position of scanner based on the information given by surface wave. Thus, the movement of a scanner can be controlled by the amount of input based on the information obtained.
Keywords
position control; ultrasound; surface wave; scanner; automated ultrasonic testing; automatic scanner;
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