Design and Analysis of a Bionic Attachment Module for Complex Surfaces

Existing attachment modules have insufficient com-pliance with curved surfaces, which limits the use of wall-climbing robots. This paper proposes and develops a bionic three-toe attachment module for complex surfaces, which has good active compliance and can significantly improve the compliance of wall climbing robots on surfaces. Based on the study of tree frogs and dexterous hands, this paper designs the structure of the bionic three-toe attachment module and carries out the related kinematic analysis. Utilizing dexterity as an evaluation index, the relationship between singularity point, isotropic point, and linkage length is further revealed. Finally, the excellent performance of the bionic three-toed attachment module in terms of active compliance and dexterity is verified through attachment compliance experiments on complex surfaces. If this module is used in the foot of wall-climbing robots, it will make the wall-climbing robots no longer limited to planar and small curvature surfaces and will be able to attach stably even in complex continuous variable curvature environments, such as the surface of the aircraft skin, the surface of the wind turbine blades, and the body of high-speed railways.

I. Introduction

For bionic wall-climbing robots to perform various tasks instead of manual labor, the compliance, stability, lightweight, and flexibility of the attachment module are of great importance to ensure that the wall-climbing robots can complete the tasks [1]. Currently, wall-climbing robots mainly adopt single attachment points [2], [3] or multi-attachment point fixed attitude layouts [4], [5] for their attachment modules. Most of the attachment modules with such layouts can only passively conform to planar surfaces or surfaces with a large radius of curvature and are unable to realize stable attachment on the small radius of curvature or complex continuous variable curvature surfaces. This limitation leads to the fact that most of the current climbing robots are used for cleaning the glass curtain walls of high-rise buildings, painting smooth and flat concrete walls, and inspecting and repairing the surfaces of flat or large radius of curvature of factory equipment, but for the surfaces of the skin of airplanes, the surfaces of the blades of wind turbines, and the bodies of high-speed railroads that have large curvature and variable curvature environments, the climbing robots that have a fixed attachment point layout of the attachment module as a foot are unable to achieve Therefore, there is an urgent need for an attachment module that has good compliance to curved surfaces.