Pose Control and Profile Tracking with Eddy Current Sensor and Robotic Arm for NDT Applications

In non-destructive testing (NDT), inspection of complex metallic parts is a challenge. At the moment, the object’s surface profile is typically obtained from design documents or through separate dedicated measurements such as optical methods. In this work, we use contactless sensing and real time feedback to control a robot to follow unseen complex surfaces in a non-contact autonomous manner. An EC sensor is fixed to the end-effector of a UR5 robotic arm, and its signals are used to control the pose of the robotic arm, keeping its axis perpendicular to the local surface and maintaining a specific lift-off distance. The metallic surface profile can then be reconstructed from the scanning trajectory of the robotic arm. In experimental verification, the surface of a cylindrical metallic pipe is reconstructed without prior information about its shape and position relative to the sensor. The accuracy of the reconstruction is better than 0.17 mm in terms of root mean square error (RMSE). Other examples of tracking and scanning a tapered exhaust pipe autonomously are also given.