I. INTRODUCTION
The industries and the livelihoods of people depend heavily on the safe and reliable operation of overhead transmission lines. The most common inspection techniques nowadays include manual inspection, inspection from a helicopter, inspection from a robot, inspection from a drone, etc. [1]. Compared with other inspection methods, drone inspection has the advantages of wide detection coverage, Due to the advantages of low operating requirements and high cost performance, drone inspections combined with manual inspections are currently widely used in actual power system work to improve work efficiency and safety. A large number of visible light images will be generated during the drone inspection process. By inspecting the visible light images, the bolts and pins in the transmission lines are missing. However, manual inspection has problems of low efficiency and high labor cost.