Geometry characterization of electroadhesion samples for spacecraft docking application

Abstract

Applications of electroadhesion include automation and inspection robots, consumer gripper devices, anchoring tools used in the military and biomedical industry, and more recently, mechanisms for spacecraft docking. The purpose of this study is to characterize geometries of electroadhesion samples for application in spacecraft docking and propose a metric to predict the interaction between geometry and captured object. Shear forces of electroadhesion samples composed of Kapton(R)Polyimide insulating material with embedded aluminum foil electrodes and three common space-rated substrate materials were measured. Responses of the electroadhesion samples configured in three geometries were identified using substrates attached to dynamic two-dimensional air bearing platforms. Geometries included a flat plate design as a prototype for cubesats, a concave, cylindrical design for potential application to circular, cylindrical spacecraft capture and torque mitigation, and a soft four-arm claw design as a prototype for docking to variable shaped objects with full coverage of object surface area. Quantitative and qualitative results were analyzed to characterize the optimal geometry for spacecraft docking. Surface area of each geometry, defined as the area of contact between electroadhesion samples implemented on the geometry and the substrate rigidly attached on air bearing platform, was compared to the stop time, defined as the time required for the geometry to mitigate both initial and residual motion of the air bearing platform. In summary, aluminized mylar substrate is identified as a superior type to achieve the highest attainable shear adhesion forces, and one electroadhesion geometry may be superior to others depending on specific docking scenarios in a space environment in agreement with the proposed metric.