Experimental evaluation of adhesive technologies for robotic grippers on micro-rough surfaces

This paper presents the performance of a newly developed adhesive that combines an electrostatic adhesive with a directional dry (gecko-like) adhesive. The focus is on the adhesive´s performance on micro-rough surfaces, which has a large number of applications in robotic mobility and manipulation such as climbing, perching, and grasping. Performance was characterized using shear/normal adhesion pressure limit curves and comparing the new hybrid adhesive to each individual adhesive mechanism and a control. Results show that the electrostatic directional dry adhesive generally performs better than a directional dry adhesive, but that on several surfaces, an electrostatic adhesive with no fibrillar mechanism performs the best. Additionally, the paper introduces a new mechanism that maintains an adhesive´s compliance on micro-rough surfaces while transmitting shear and normal forces to a rigid structure. The mechanism is experimentally compared to a rigid backing and a gecko-like hierarchical suspension layer. Results show that the mechanism performs the best when subjected to mainly normal loads, but a hierarchical suspension handles shear loads better.