Wind Turbine Crack Inspection Using a Quadrotor With Image Motion Blur Avoided

The camera-equipped quadrotor is a preferable choice for wind turbine blade (WTB) crack inspection applications with the benefits of high portability and low cost. Unfortunately, the high speed of the quadrotor might cause image motion blur which leads to a crack detection failure. Recent works cope with this by adopting the advanced camera systems or image deblurring techniques, which, however, usually require additional hardware or extra computational load. In this paper, the crack detection failure problem caused by image motion blur is handled by means of quadrotor motion control. First, the desired speed range that can avoid the detection failure caused by the image motion blur is experimentally obtained. Then, a speed regulation controller is developed to regulate the quadrotor flying speed within the obtained range. Experimental studies for crack inspection of a WTB using a camera-equipped quadrotor under wind condition are carried out to validate the effectiveness of the proposed strategy. Compared to the traditional approach without image motion blur avoidance, with the same inspection assignment and wind condition, the proposed method can obtain better quality images with 4.08 higher peak signal-to-noise ratio (PSNR) and 0.1 higher structural similarity index (SSIM) on average, where PSNR and SSIM are two typical image quality assessment metrics. As a result, the crack detection failure problem is avoided and a successful WTB crack inspection is achieved.