Nanostructured electroadhesive and electrofrictive surfaces for dexterous grasping and manipulation

Abstract

Robots will become commonplace in personal, public, and working environments and must be equipped for a broad range of manipulation tasks and physical encounters. Traditional robotic grasping methodologies like opposed fingers, suction cups or gecko based adhesion have advanced, yet new grasping technologies are needed, especially for delicate and fragile objects. One promising surface adhesion methodology is electroadhesion, which uses patterns of electrodes that induce charge in a target object. Grasping by electroadhesion is attractive because of its capability to produce surface adhesion on wide range of substrates, its electrically controllable nature and its low power consumption and mechanical simplicity. However, many of these studies are restricted to studying the design of flat and rigid electroadhesive pads and lack understanding of interfacial contact mechanics driven by electrostatics crucial for its scalability and successful deployment.

This thesis aims to develop the fundamental understanding necessary to realize scalable, high-performance electroadhesives built from compliant nanostructured surfaces. In particular, an array of conductive nanofibers (specifically carbon nanotubes), coated with a thin dielectric, exhibits extremely low off-state adhesion, yet a high onstate adhesion because these fibers not only conform to the target object but also provide high polarization due to the use of a thin dielectric coating. In this thesis, the following interrelated research objects are presented: (1) Analytical and numerical modeling of charge accumulation in conductive nanofiber arrays coated with thin dielectric materials. (2) Investigation of coupling between electrostatic charging of conductive nanofibers, their surface compliance, morphology, adhesion using theoretical contact mechanics models. (3) Corroboration of theoretical contact mechanics model for adhesion using molecular dynamics simulations.

(4) Experimental investigation of tunable adhesion and friction using atomic force microscopy (AFM). The ultimate goal of this thesis is to therefore enable the design of SNEs with electrically tunable adhesion and friction towards a universal grasping methodology.