Lift-off suppression algorithm for dual-frequency alternating current field measurement

Since the surface of the aviation equipment structure is mostly rivet connectors, it is easy to produce lift-off disturbances during the inspection process, resulting in missing detection or misjudgment of defects. Based on the alternating current field measurement, this paper introduced dual-frequency excitation technology, designed and developed a set of integrated the dual-frequency ACFM detection system for structural defects which integrates detection probe, dual-frequency excitation and detection chassis, studied the mechanism of interference signal distortion under lift-off jitter conditions, and proposed an ACFM lift-off jitter suppression algorithm based on dual-frequency response signals, and carried out lift-off jitter suppression experiment, the experimental results show that the dual-frequency ACFM lift-off suppression algorithm can effectively remove the interference signal caused by the lift-off disturbance, and enhance the accuracy of the defect signal judgment.