During the long-term outer door field service

transmission lines will encounter strikes of lightning

corro-sion of chemical contaminants’

ice-shedding

insulators’ flashover

wind vibration of conductors

lines’ gallopingand external forces’ destroy

which will generally bring a series of latent faults such as both strands to fracture

dam-age of hardware

deterioration of insulators and so forth. It will induce some fatal accidents such as transmission lines’ broken and insulator strings failed off which have a very strong impact on the safe operation of power grids that if thelatent faults cannot be recognized and restored as early as possible. In China

the common means to be used for la-tent faults inspection of transmission lines is manually and periodically examined by workers. Recently

with the de-velopment of both the artificial intelligence technologies and the smart grid

transmission line maintenance robothave been one of the research hotspots around the world owing to its features of safety

high efficiency and precise. Inthis paper

the authors will introduce the fundamental principle

methods and achievements applying the intelligentrobots for the on-line maintenance of transmission lines firstly. Then some problems of applying the intelligent robotsfor the on-line maintenance will be proposed. At last

some key technologies need to be solved will be discussed. Allin all

the achievements of this paper can be provided as technical references for developing and applying intelligentrobots.