Electroadhesive Robot Climbers

Electroadhesive Robot from SRI International

By now, most roboticists are familiar with the myriad gecko-type robots that employ Van der Waals forces (created by microscopic synthetic setae) to cling to walls.  Less well-known is the work on an electrically-controllable alternative developed by researchers at SRI International (formerly called Stanford Research Institute) called "electroadhesion".  Impressively, the electroadhesive can support 0.2 to 1.4 N per square centimeter, requiring a mere 20 micro-Watts per Newton.  This means that a square meter of electroadhesive could hold at least 200kg (440 lbs) while only consuming 40 milli-Watts, and could turn on and off at the flick of a switch!  Read on for pictures, videos, and discussion.

First, I think it is prudent to examine the competing gecko-style Van der Waals robots that employ microscopic synthetic setae to generate adhesive forces via intermolecular interactions.  This technique is employed in nature by real geckos (shown below).

Geckos' microscopic setae

The technique has been mimicked by researchers, as shown below.  [The material on gecko-type adhesives is taken from the following websites.]

Stickybot Robot Gecko   Robot Gecko Synthetic Setae   Robot Gecko Synthetic Setae

Unfortunately, there is no way to deactivate intermolecular forces; the gecko's feet are always "sticky".  Meanwhile, electroadhesives use the electrostatic force generated between high-voltage electrodes on the robot and the surface / substrate, as shown below.

Electroadhesive Robot Principle 

Of course, this material can be employed to support large loads, but more importantly for our purposes, build cool climbing robots!

Electroadhesion supporting large weight  Electroadhesive Robot  Electroadhesive Robot

Many different robot designs have been considered by the SRI researchers.

Electroadhesive Robot Concept  Electroadhesive Robot Concept

Very cool stuff!  The videos below, though short, show the effect in action on a variety of surfaces (from wood, drywall, cement, glass, and steel).

If you'd like to learn more about SRI's electroadhesive robots, I'd recommend checking out their website or the ICRA 2008 paper.

 

Comments

does anyone know which materials are good to use if i want to build one of these robots
—Anonymous

@Anonymous

I would also be interested to know about the electrodes' material composition, and would like to take a stab at building one.  If / When I ever find the time, my first experiments would probably be copper tape on cellophane (or something to that effect).  Then I'd probably move on to Kapton.  I'm guessing the bigger problem will be dielectric breakdown at the high voltages required...

—Travis Deyle

Hey guys,

 

Im curious how they actually make the electroadhesion be continuous.. any circuit can be provided? =)

—Anonymous
I'd bet that it uses at least 30kv and you can find the circuit googling for high voltage cascade multiplier i am interested too, more in a kind of spiderman suit .
—Anonymous

@Anonymous,

In their paper, they note actuation voltages between 1-5kV with ~15 nA / Newton of current.  In a previous life, I actually designed a small (2cm3-ish) device that could perform this handily -- basically, a flyback transformer connected to a multi-stage Cockroft-Walton voltage multiplier, all controlled via I2C bus. 

If properly incintivized, it would be fun to revisit that old project and make some electroadhesive systems!

—Travis Deyle
I wish I had read this page in the beginning of my thesis :-S Thanks for the very nice briefe to this technology here :-)
Shahab

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