Design and analysis of a passive adaptive wall-climbing robot based on five-bar mechanisms

Due to the inspection demand of curved permeable metal walls, such as large ships, a wall-climbing robot that can adapt to various curvatures of metal walls is built to solve the problems of unstable adsorption and poor adaptability of rigidly-connected wall-climbing robots. Two relatively independent passive adaptive moving devices are designed using the five-link mechanism to fit active wheels to both convex and concave surfaces. It can also make the two driving wheels fit onto convex surfaces with different curvatures. Static and dynamic models are developed to obtain the minimum adsorption force and torque required for the robot to move stably on the wall. A permanent magnet wheel is designed and the magnitude of the adsorption force generated when it is rotated at different thicknesses of the wall is analyzed. Three different magnetic circuit models of the gap-type permanent magnet adsorption device are proposed and parametrically simulated to analyze the effect of gap variation on the adsorption force. And experimental verification was conducted on three models. Finally, the prototype is built, and the motion performance experiments are conducted. The results show that the 5-bar mechanism improves the adaptability of the robot by adjusting its posture so that the driving wheels can fit the wall completely. The permanent magnet wheels can provide a large adsorption force, which enhances the stability of the robot. It provides a basis for the intelligent development of shipbuilding enterprises.