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Linear motors and positioning on submerged NDE equipment
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
2013 (English)Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

WesDyne Sweden AB is a wholly owned subsidiary of Westinghouse Electric Sweden and a leading company within mechanized non-destructive testing methods for the inspection of nuclear power plants. They design, manufacture and use inspection platforms (manipulator systems) to scan for defects in and around the welds in the reactor vessels. Currently most manipulator motions utilize a rotating motor with encoder (for positioning feedback) with various kinds of transmissions such as belt drives, leadscrews, rack/pinion drives etc.


The aim of the project was to investigate the possibilities to use linear motors (direct drive motors) instead of today’s rotating motor with transmissions. Rotating motors with transmissions are not optimal due to their shape, size and weight which often leads to placing the motor far from the operating area. Replacing them with linear motors, so called direct drive motors, would bring down the size of the manipulator system, give a faster moving/scanning procedure and a more precise positioning.


This thesis shows that it is possible to replace todays rotating motors with linear direct drive motors. This would result in greater accuracy, higher speeds, reduced operator safety risk due to less moving parts, a smoother continuous motion and thus probably better measuring results. The downside is that the examined motors together with their bearing arrangement are heavy; so heavy that they can not manage to meet the specification of requirements. Additionally, further tests are needed to evaluate the performance and radiation resistance of the new motors. 

Place, publisher, year, edition, pages
2013. , 26 p.
, MA, 1425
National Category
Mechanical Engineering
URN: urn:nbn:se:umu:diva-97639OAI: diva2:774826
External cooperation
WesDyne Sweden AB
Subject / course
Educational program
Bachelor of Science Engineering in Mechanical Engineering
Available from: 2015-01-13 Created: 2014-12-29 Last updated: 2015-01-13Bibliographically approved

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