Scaling Hard Vertical Surfaces with Compliant Microspine Arrays

Abstract

A new approach for climbing hard vertical surfaces has been developed that allows a robot to scale concrete, stucco, brick and masonry walls without using suction or adhesives. The approach is inspired by the mechanisms observed in some climbing insects and spiders and involves arrays of microspines that catch on surface asperities. The arrays are located on the toes of the robot and consist of a tuned, multi-link compliant suspension. The fundamental issues of spine allometric scaling versus surface roughness are discussed and the interaction between spines and surfaces is modeled. The toe suspension properties needed to maximize the probability that each spine will find a useable surface irregularity and to distribute climbing loads among many spines are detailed. The principles are demonstrated with a new climbing robot, SpinybotII, that can scale a wide range of flat exterior walls, carry a payload equal to its own weight, and cling without consuming power. The paper also reports how toe parameters scale with robot mass and how spines have also been used successfully on the larger RiSE robot

Touchdown to take-off: at the interface of flight and surface locomotion

“…Once interlocked, the claw is constrained only by its mechanical strength, determined by the shape and material of the claw [86]. For high rugosity surfaces, such as stone, stucco or concrete, the number of 'usable' asperities per unit area scales with the inverse of the tip radius [190]. Furthermore, stress varies with the square of the tip radius [190].…”

“…For high rugosity surfaces, such as stone, stucco or concrete, the number of 'usable' asperities per unit area scales with the inverse of the tip radius [190]. Furthermore, stress varies with the square of the tip radius [190]. Therefore, for a given surface, isometrically larger animals will find fewer usable asperities, and their contact points will be more prone to failure, either from claw or surface fracture [86].…”

Design and Fabrication of the Harvard Ambulatory Micro-Robot

“…This experiment does not prove vertical locomotion but provides the foundation of research on one form of dry adhesion. Further research will explore the claw geometry [1] and body mechanics necessary to climb vertical surfaces of varying roughness. …”

On the Comparative Analysis of Locomotory Systems with Vertical Travel

“…While specific resistance has been compared for a variety of ground vehicles-an exhaustive comparison at time of publication is in [8]-no similar comparison has been performed for climbing robots. With dynamic and efficient climbers [3,5,10], as well as various other robots that climb on a variety of surfaces at differing speeds [13,1,9], we believe the lack of a formal comparison to be something that needs addressing in the climbing robot community. This paper outlines a methodology by which specific resistance can be applied to climbing robots-even those that only climb on sloped surfaces rather than vertical, such as in [2,5]-and compared to other climbing robots as well as to the growing list of ground robots covered in work such as [8].…”