Pose control and profile tracking with eddy current sensor and robotic arm for NDT applications

For industrial quality control, non-destructive testing (NDT) of complex metallic parts relies on the accurate knowledge of the object's surface profile. Currently, this information is typically obtained through design documents or separate dedicated measurements. This study realizes non-contact, accurate reconstruction of metallic surface profiles, eliminating the need for obtaining prior knowledge of the object's shape and position relative to the sensor. An EC sensor is fixed to the end-effector of a UR5 robotic arm (RA), and its signals are used to control the pose of the RA, keeping its axis perpendicular to the local surface and maintaining a specific lift-off distance. The metallic surface profile can be reconstructed from the scanning trajectory of the RA. In experiments, the surface of a cylindrical metallic pipe is reconstructed without prior information, with the root mean square error (RMSE) of the surface profile being lower than 0.17 mm. An example of automatic tracking and scanning of a tapered exhaust pipe is also provided.