I. Introduction
In The transmission line (TL), there is a kind of device that plays the role of positioning, connecting, and reinforcing different transmission devices, which is called TL fastener. Once the working state of TL fastener is abnormal, the power system will be seriously threatened. However, TLs are exposed to complex backgrounds, such as mountains and rivers, and extreme weather conditions, such as snow and rain. This long-term wear will greatly increase the probability of abnormal state of TL fasteners. Therefore, regular defect detection of TL fasteners is a necessary and meaningful task.