Task Description:

Gecko-inspired adhesive nano-structures on robot toes will increase the capability for small robots to scamper up rocks, walls, and smooth surfaces by increasing both friction and adhesion. We propose to fabricate patches of a novel dry adhesive based on insights gained from recent studies in the Full/Autumn labs of gecko hair function. We will develop a fabrication process to economically mold large arrays of hairs in centimeter or larger diameter patches. In cooperation with the Cutkosky lab at Stanford, we will specify foot mechanics and sensing for optimal attachment and release of adhesive patches during locomotion.

Task 2: Preflex Mechanisms

Task 2.1.1. Dry Adhesive
Analysis and modeling of synthetic gecko hair patches. We will develop models for the mechanical and geometrical properties of synthetic gecko hair arrays to allow robot feet to adhere to rough and smooth surfaces.

a) using biological results from Full/Autumn labs, develop mathematical/mechanical models of spatulae, spatular hairs, setal hairs, and lamella arrays.
b) model interactions with rough and smooth surfaces.
c) communicate results with foot design groups.
d) publish key findings.

Synthesis and testing of synthetic gecko hair patches. We will design a fabrication process for synthetic hair arrays, and test adhesive capabilities of the arrays.

a) using analytical models of gecko hair design and function, develop fabrication process for synthetic hair patches.
b) using atomic force microscope, test adhesive and friction properties of patches.
c) share samples with Autumn lab for comparison to natural gecko hair arrays, and with Cutkosky lab for mounting on RiSE feet.
d) publish key findings.

Task 2.2.1. Clawed Sticky Feet
Develop foot and gecko hair interaction model. We will develop a model, based on individual hair contact properties, to determine how individual toes and a whole foot should make contact with various surfaces to ensure solid contact and release.
a) develop model for optimal foot compliance characteristics.
b) communicate with Cutkosky Lab to transfer design concepts to SDM foot fabrication.
c) publish key findings.

Phase 1 (M1-18)

M6
Using recent biological results from Full/Autumn labs, fabricate prototype 1 sq. cm. adhesive array with friction coefficient of > 1.0 with compressive loading for glass surface roughness of less than 0.2 micron. Provide samples to Autumn lab for testing compared to real geckos. Provide mockup samples to Cutkosky lab for mounting tests
with RiSe foot.

M12
Using biological results from Full/Autumn labs on surface roughness effects, fabricate prototype 1 sq. cm. adhesive array with target adhesion of 0.1 atmosphere and friction coefficient > 1.0 for surface roughness of 0.2 microns. Provide samples to Autumn lab for testing compared to real geckos. Provide samples to RiSE development team to place patches on toes to increase friction on smooth surfaces.

M18
Using biological results from Full/Autumn labs on lamellae structures, fabricate prototype 1 sq. cm. adhesive array with target adhesion of 0.1 atmosphere for surface roughness of 2 microns. Provide samples to Autumn lab for testing compared to real geckos. Provide samples to RiSE development team for mounting on toes with adhesion of 0.1 atmosphere on 0.2 micron smooth glass.

Phase 2 (M19-36)

M24
Using biological results from Full/Autumn labs on self-cleaning gecko structures, fabricate prototype 1 sq. cm. adhesive array with target adhesion of 1.0 atmosphere for surface roughness of 20 microns. Provide samples to Autumn lab for testing compared to real geckos.

M30
Working with RiSE and Full/Autumn labs, determine optimal toe
kinematics for gecko hair patch engagement and release.

Phase 3 (M37-60)
M42

Using biological results from Full/Autumn labs on attach/release mechanics, and RiSE toe capabilities, develop synthetic gecko hair patches and lamellae which have 1.0 atmosphere adhesion up to surface roughness of 200 microns. Provide prototype toe patch material to RiSE team for rough surface testing and to Full/Autumn labs for
comparison to real gecko.

M48
Using biological results from Full/Autumn labs on attach/release mechanics, and RiSE toe capabilities, develop synthetic gecko hair patches and lamellae which have long life-time, and self-cleaning capabilities. Provide prototype toe patch material to RiSE team for self-cleaning testing and to Full/Autumn labs for comparison to real gecko.

M54
In laboratory, using RiSE leg/foot/toe module, demonstrate RiSE wall climbing and traverse force capability using refined synthetic gecko hair patches. Transmit results on climbing results to RiSE leg/body control team.

M60
RiSE team demonstrates RiSE running up and across vertical smooth or rough wall using synthetic gecko toes in combination with claw mechanism developed at Stanford.