Grappling claws for a robot to climb rough wall surfaces: Mechanical design, grasping algorithm, and experiments

Abstract

Wall-climbing robots have been widely applied in the inspection of smooth walls. However, only a few adhesion methods have been developed for robots that will allow them to climb cliffs and dusty, high-altitude, rough walls (constructed using coarse concrete, bricks, and stones, etc.) that may be subjected to vibrations. This paper proposes a suitable adhesion method that employs grappling-hook-like claws arranged in a cross shape. First, we address the implementation mechanism required. Then, a method of extracting the characteristic parameter is revealed rough wall was devised, 3D profiles of rough walls were simulated, and the discriminant conditions necessary for the claws to stably grasp the wall were provided. A method of triangulation is proposed to judge which regions of a 3D wall can be gripped, and we subsequently present a grasping discrimination algorithm for the interaction between the miniature claws and 3D wall profile. Finally, a prototype of the grappling-hook-like claw system was fabricated. A test platform was built to test the robot which incorporates an electromagnetic vibration shaker to simulate a vibrating wall. Experiments were then carried out on the robot using the vibrating wall and a random outdoor wall. The results verified the feasibility of the proposed claws and the validity of the discriminant algorithm for gripping 3D walls. Compared with traditional adhesion approaches, the proposed method (based on hook-like claws) is more adaptable to suit various types of wall. It also has higher resistance to disturbances and so provides a more reliable method of adhesion for robots on rough walls.