An active whisking based remotely deployable NDE sensor

The fundamental sensitivity characterisation of a novel whisking sensor for applications in Non-Destructive Evaluation (NDE) is presented. Whisking sensors, originally developed for proximity detection applications in autonomous robotics, have been evaluated for measurements of surface roughness and surface form change. These surface parameters are representative of the typical changes associated with corrosion and surface breaking defects in real structures. The authors demonstrate that the whisking sensor can be used to accurately quantify surface roughness in the range 14-53 μm with excellent correlation (> 0.97) to a standard reference. Furthermore it is shown that that the sensor can detect 14mm diameter flat bottomed holes with depths ranging from 0.4 to 1.0 mm. In contrast to conventional ultrasonic and eddy current techniques, the sensor is insensitive to surface lift –off, producing an error of only 1.2% for lift-offs of several mm. This lift-off insensitivity is a highly desirable characteristic for real-world deployment of the sensors, and the authors describe how the sensor can be incorporated into autonomous inspection robots.