Abstract: With a three-arm inspection robot taken as an example， a hierarchical planning control strategy was analyzed and divided into a line information library layer， an action planning layer and an execution planning layer. The line information library layer is based on the known information of the high-voltage transmission line to be detected， including information on the type， location， and quantity of obstacles. The overall action planning layer and the execution planning layer are summarized according to the finite-state machine theory that when the input event is a (the second layer of the action planning layer)， under the action of f (the third layer of the execution layer)， the state q (the robot’s initial state) is mapped to the state p (the robot’s termination state). In the end， the trajectory planning of this robot was simulated by Matlab and the experiment of the prototype laboratory spanning the anti-vibration hammer and overhanging metal fittings， whose results verified the effectiveness and feasibility of the control strategy and the trajectory planning method.

Key words: inspection robot, obstacle-crossing, hierarchical planning, finite-state machine, trajectory planning