The charge-coupled device camera has 128 channels, with a 0.2 mm width for a single element. We then built an
algorithm from which the output of an element from a central part of the charge-coupled device camera became the maximum in order that the inspection robot could turn by adjusting its position on the pipe as shown in Fig. 6(a). We then executed a driving test on a steel pipe with a diameter of 750 mm. The attractive force for the steel pipe used the magnetic force of the electromagnet in the EMAT.