Path planning for eddy current inspection around probable defects

Part quality is an important aspect in the aerospace industry to avoid unpredictable and irreversible damages and to ensure a long lifecycle. To ensure quality, nondestructive testing techniques are applied on parts, and one of the most frequently used in the aerospace industry is eddy current testing (ECT). However, high-cost, time-consuming ECT is still mainly performed manually. In this case, reliability and repeatability of inspection results are also limited due to their high dependence on the human operator. As part of an effort to robotize ECT with a six degree-of-freedom manipulator arm and thus, free oneself from the many drawbacks of manual inspections, the authors previously proposed a coverage path planning methodology dedicated to complex aeronautical surfaces. However, orientation of the probe along these paths was not initially considered during this previous work, although it is just as important as position information given that the probe must keep a normal orientation with respect to the surface to inspect it reliably. Following on from this previous work, the computation of these orientations along every point of the path is presented in this paper. Furthermore, another coverage path planning methodology is developed to inspect with ECT around a probable defect whose position is assumed to be known a priori. After positions and orientations along inspection paths are computed, a simulation with a robotic simulation software (MotoSim) is made to generate the joint trajectories of a manipulator arm MotoMan SV3XL and to teach it the automated inspection task. Afterwards, experiments using this manipulator, with a mock-up that represents a probe, are realized. After these first experiments, it is observed that the motion of the robot is what one can expect during an efficient inspection around a known indication.