Integrated vision system for supervision and guidance of a steam generator tube inspection manipulator

In this paper we present a machine vision system for supervision and guidance of a tube inspection manipulator used for eddy-current inspections of steam generators in nuclear and thermal power plants. Operation of nuclear power plants is regulated by very strict safety standards. In one inspection cycle a few hundred out of a mesh of approximately 6,000 tubes need to be tested, so omissions and misidentifications can occur. A supervisory vision system is introduced into the inspection manipulator motion control loop to increase its reliability and enable full automation of the inspection procedure. The developed system supervises robot movements over the tube mesh and verifies that the eddy-current probe is positioned into the desired tube. On final approach of the manipulator arm to the tube opening, the vision system automatically guides the manipulator to achieve accurate positioning for probe insertion, thus eliminating the need for operator input and reducing probe wear.