Abstract: To enable the capacity of climbing robots to work on steep surfaces, especially on inverted surfaces, is a fundamental but challenging task. This capacity can extend the reachable workspace and applications of climbing robots. A track-type inverted climbing robot called SpinyCrawler was developed in this paper. Using a spiny track with an opposed gripping mechanism, the robot was experimentally demonstrated to have the ability of generating considerable adhesion to achieve stable inverted climbing. First, to guarantee reliable attachment of the robot on rough ceilings, a spiny gripper inspired by the opposed gripping prolegs of caterpillars is designed, and a gripping model of the interaction between spines and the ceiling asperities is established and analyzed. Second, a spiny track is developed by assembling dozens of spiny grippers to enable continuous attachment. A cam mechanism is introduced in the robot design without extra actuators to achieve stable attachment and easy detachment during continuous climbing. Finally, climbing experiments are conducted on different surfaces, using a SpinyCrawler prototype. Experimental results demonstrated stable climbing ability on various rough inverted and vertical surfaces, including concrete walls, crushed stone walls, sandpaper walls, brick walls, and brick ceilings.

Key words: inverted climbing, track-type robot, rough ceiling, bio-inspired spiny gripper