Kenichi Otani

SIGNAL EVALUATION SYSTEM OF FLEXIBLE ARRAY ECT PROBES FOR INSPECTING COMPLEXLY SHAPED SURFACES

We developed a signal evaluation system of flexible array eddy current testing (ECT) probes for inspecting complexly shaped metal surfaces. Our probes employ excitation and pickup coil pairs arrayed on a bendable substrate to measure curved targets. Since the developed probes produce signals due to the change in the relative position between the coil pair, an evaluation module for flaw signal identification is integrated into the system. The identification utilizes signal phase combination of the coil pairs. It is represented as a two‐dimensional diagram constituting the phase values of two of the coil pairs with different positions. The phase of signals around flaws is significantly affected by their orientations. The diagram is therefore capable of separating flaw information from other information and of imaging flaw positions. We applied the system to complex geometric mock‐ups. Flaw signals were successfully identified and the images obtained for identified positions could be used to efficiently meas...

Development of a swim-type ROV for narrow space inspection

ABSTRACT The swim-type remotely operated vehicle (ROV) for inspection of narrow spaces in nuclear power plants has been developed. Many structures are crowded in a confined space at regular intervals in the bottom area of a reactor. So, the thickness of the ROV shape is an important design point to ensure that the ROV can move in the space. The developed ROV has a three-dimensional swimming mechanism using six thrusters, three cameras for observing the position while moving and for making inspections easily, and a localization system. The localization system combines two elements: a gyroscope to detect the progression direction; and a slit laser that detects the progression distance using the optical cutting method. The localization method is called the modified inertial navigation (MIN) method and it was evaluated in a mock-up examination. The ROV was able to move smoothly using the MIN method and its position could be detected without making a mistake in the route followed.