It is very demanding on navigation,location and obstacle avoidance ability for UAV to execute cable tun-nel inspection because underground cable trench is with heat and humidity,and narrow containing many obstaclessuch as cable cable racks. In addition,cables are laid underground in the tunnel where there are existing up anddown slopes and bends,and it is hard to get GPS signal. Therefore,it is necessary to develop special techniques forUAV-based underground cable trench inspection. In this research,a laser...