Detection device

A detection device, comprising:

• a sensor head to acquire a plurality of pieces of surface data of a long body having a periodic pattern on a surface thereof, the sensor head configured to acquire, at different positions in a longitudinal direction of the long body, the plurality of pieces of surface data in a direction orthogonal to the longitudinal direction of the long body;
• and
• circuitry configured to
• store first reference data and second reference data, the first reference data and the second reference data having a same period as a period of the pattern formed on the surface of the long body in a direction orthogonal to the longitudinal direction of the long body, the second reference data having a phase shifted from a phase of the first reference data;
• select first surface data and second surface data from the pieces of surface data acquired by the sensor head;
• calculate a first similarity between the selected first surface data and the first reference data, a second similarity between the selected first surface data and the second reference data, a third similarity between the selected second surface data and the first reference data, and a fourth similarity between the selected second surface data and the second reference data;
• calculate, as a first phase, a deflection angle of a first similarity vector having the calculated first similarity and the calculated second similarity as elements and, as a second phase, a deflection angle of a second similarity vector having the calculated third similarity and the calculated fourth similarity as elements;
• calculate a period of the pattern formed on the long body on the basis of the calculated first phase and the calculated second phase;
• and
• detect an abnormality in the long body on the basis of the calculated period.

A detection device, comprising:

• a sensor head to acquire first surface data of a first long body having a periodic pattern on a surface thereof and second surface data of a second long body having, on a surface thereof, a same pattern as the pattern formed on the surface of the first long body, the sensor head configured to acquire the first surface data in a direction orthogonal to a longitudinal direction of the first long body and to acquire the second surface data in a direction orthogonal to a longitudinal direction of the second long body;
• and
• circuitry configured to
• to store first reference data and second reference data, the first reference data and the second reference data having a same period as a period of the pattern formed on the surface of the first long body in a direction orthogonal to the longitudinal direction of the first long body, the second reference data having a phase shifted from a phase of the first reference data;
• calculate a first similarity between the first surface data acquired by the sensor head and the first reference data, a second similarity between the first surface data acquired by the sensor head and the second reference data, a third similarity between the second surface data acquired by the sensor head and the first reference data, and a fourth similarity between the second surface data acquired by the sensor head and the second reference data;
• calculate, as a first phase, a deflection angle of a first similarity vector having the calculated first similarity and the calculated second similarity as elements and, as a second phase, a deflection angle of a second similarity vector having the calculated third similarity and the calculated fourth similarity as elements;
• and
• detect that an abnormality has occurred in the first long body or the second long body on the basis of the calculated first phase and the calculated second phase.