Mark R. Cutkosky is the Fletcher Jones Professor in the Dept. of Mechanical Engineering at Stanford University. He joined Stanford in 1985, after working in the Robotics Institute at Carnegie Mellon University and as a design engineer at ALCOA, in Pittsburgh, PA. He received his Ph.D. in Mechanical Engineering from Carnegie Mellon University in 1985.Cutkosky’s research activities include robotic manipulation and tactile sensing and the design and fabrication of biologically inspired robots. He has graduated 48 Ph.D. students and published extensively in these areas. He consults with companies on robotics and human/computer interaction devices and holds several patents on related technologies. His work has been featured in Discover Magazine, The New York Times, National Geographic, Time Magazine and other publications and has appeared on PBS NOVA, CBS Evening News, and other popular media.Cutkosky’s awards include a Fulbright Faculty Chair (Italy 2002), Fletcher Jones and Charles M. Pigott Chairs at Stanford University, an NSF Presidential Young Investigator award and Times Magazine Best Innovations (2006) for the Stickybot gecko-inspired robot. He is a fellow of ASME and IEEE and a member of Sigma Xi.<h1 dir="ltr">Soft Robotics With Mark Cutkosky&nbsp;</h1>Marwa ElDiwiny, host of the Soft Robotics podcast, interviews Mark about his work in soft robotics.<iframe src="https://open.spotify.com/embed-podcast/episode/6237w6uZUttAH7nW4lhAPf" width="100%" height="232" frameborder="0" allowtransparency="true" class="fr-draggable"></iframe>

Cutkosky applies analyses, simulations, and experiments to the design and control of robotic hands, tactile sensors, and devices for human/computer interaction. In manufacturing, his work focuses on design tools for rapid prototyping.

Soft Robotics With Mark Cutkosky "Gecko Climbing Robots"

Right now, about 500,000 pieces of human-made debris are whizzing around space, orbiting our planet at speeds up to 17,500 miles per hour. This debris poses a threat to satellites, space vehicles and astronauts aboard those vehicles.What makes tidying up especially challenging is that the debris exists in space. Suction cups don&rsquo;t work in a vacuum. Traditional sticky substances, like tape, are largely useless because the chemicals they rely on can&rsquo;t withstand the extreme temperature swings. Magnets only work on objects that are magnetic. Most proposed solutions, including debris harpoons, either require or cause forceful interaction with the debris, which could push those objects in unintended, unpredictable directions.To tackle the mess, researchers from Stanford University and NASA&rsquo;s Jet Propulsion Laboratory (JPL) have designed a new kind of robotic gripper to grab and dispose of the debris, featured in the June 27 issue of Science Robotics.<blockquote>&ldquo;What we&rsquo;ve developed is a gripper that uses gecko-inspired adhesives,&rdquo; said <a href="https://profiles.stanford.edu/mark-cutkosky" target="_blank">Mark Cutkosky</a>, professor of mechanical engineering and senior author of the paper. &ldquo;It&rsquo;s an outgrowth of work we started about 10 years ago on climbing robots that used adhesives inspired by how geckos stick to walls.&rdquo;</blockquote>The group tested their gripper, and smaller versions, in their lab and in multiple zero-gravity experimental spaces, including the International Space Station. Promising results from those early tests have led the researchers to wonder how their grippers would fare outside the station, a likely next step.<iframe src="https://www.youtube.com/embed/6hHv4li2JbY?&wmode=opaque" frameborder="0" allowfullscreen="" class="fr-draggable" style="width: 1114px; height: 645px;"></iframe>&ldquo;There are many missions that would benefit from this, like rendezvous and docking and orbital debris mitigation,&rdquo; said Aaron Parness, MS &rsquo;06, PhD &rsquo;10, group leader of the Extreme Environment Robotics Group at JPL. &ldquo;We could also eventually develop a climbing robot assistant that could crawl around on the spacecraft, doing repairs, filming and checking for defects.&rdquo;<h2>Creating a gecko gripper</h2>The adhesives developed by the&nbsp;<a href="http://bdml.stanford.edu/" target="_blank">Cutkosky lab</a> have previously been used in climbing robots and even a system that allowed humans to&nbsp;<a href="http://news.stanford.edu/news/2014/november/gecko-inspired-device-112114.html" target="_blank">climb up certain surfaces</a>. They were inspired by geckos, which can climb walls because their feet have microscopic flaps that, when in full contact with a surface, create a Van der Waals force between the feet and the surface. These are weak intermolecular forces that result from subtle differences in the positions of electrons on the outsides of molecules.The gripper is not as intricate as a gecko&rsquo;s foot &ndash; the flaps of the adhesive are about 40 micrometers across while a gecko&rsquo;s are 200 about nanometers &ndash; but the gecko-inspired adhesive works in much the same way. Like a gecko&rsquo;s foot, it is only sticky if the flaps are pushed in a specific direction but making it stick only requires a light push in the right direction. This is a helpful feature for the kinds of tasks a space gripper would perform.&ldquo;If I came in and tried to push a pressure-sensitive adhesive onto a floating object, it would drift away,&rdquo; said Elliot Hawkes, MS &lsquo;11, PhD &lsquo;15, a visiting assistant professor from the University of California, Santa Barbara and co-author of the paper. &ldquo;Instead, I can touch the adhesive pads very gently to a floating object, squeeze the pads toward each other so that they&rsquo;re locked and then I&rsquo;m able to move the object around.&rdquo;The pads unlock with the same gentle movement, creating very little force against the object.The gripper the researchers created has a grid of adhesive squares on the front and arms with thin adhesive strips that can fold out and move toward the middle of the robot from either side, as though it&rsquo;s offering a hug. The grid can stick to flat objects, like a solar panel, and the arms can grab curved objects, like a rocket body.One of the biggest challenges of the work was to make sure the load on the adhesives was evenly distributed, which the researchers achieved by connecting the small squares through a pulley system that also serves to lock and unlock the pads. Without this system, uneven stress would cause the squares to unstick one by one, until the entire gripper let go. This load-sharing system also allows the gripper to work on surfaces with defects that prevent some of the squares from sticking.The group also designed the gripper to switch between a relaxed and rigid state.&ldquo;Imagining that you are trying to grasp a floating object, you want to conform to that object while being as flexible as possible, so that you don&rsquo;t push that object away,&rdquo; explained Hao Jiang, a graduate student in the Cutkosky lab and lead author of the paper. &ldquo;After grasping, you want your manipulation to be very stiff, very precise, so that you don&rsquo;t feel delays or slack between your arm and your object.&rdquo;<h2>Gecko-inspired adhesive in zero-G</h2>The group first tested the gripper in the Cutkosky lab. They closely measuredhow much load the gripper could handle, what happened when different forces and torques were applied and how many times it could be stuck and unstuck. Through their partnership with JPL, the researchers also tested the gripper in zero-gravity environments.In JPL&rsquo;s Robodome, they attached small rectangular arms with the adhesive to a large robot, then placed that modified robot on a floor thatresembled a giant air-hockey table to simulate a 2D zero-gravity environment. They then tried to get their robot to scoot around the frictionless floor and capture and move a similar robot.&ldquo;We had one robot chase the other, catch it and then pull it back toward where we wanted it to go,&rdquo; said Hawkes. &ldquo;I think that was definitely an eye-opener, to see how a relatively small patch of our adhesive could pull around a 300 kilogram robot.&rdquo;Next, Jiang and Parness went on a parabolic airplane flight to test the gripper in zero gravity. Over two days, they flew a series of 80 ascents and dives, which created an alternating experience of about 20 seconds of 2G and 20 seconds of zero-G conditions in the cabin. The gripper successfully grasped and let go of a cube and a large beach ball with a gentle enough touch that the objects barely moved when released.Lastly, Parness&rsquo;s lab developed a small gripper that went up in the International Space Station (ISS), where they tested how well the grippers worked inside the station.Next steps for the gripper involve readying it for testing outside the space station, including creating a version made of longer lasting materials able to hold up to high levels of radiation and extreme temperatures. The current prototype is made of laser-cut plywood and includes rubber bands, which would become brittle in space. The researchers will have to make something sturdier for testing outside the ISS, likely designed to attach to the end of a robot arm.Back on Earth, Cutkosky also hopes that they can manufacture larger quantities of the adhesive at a lower cost. He imagines that someday gecko-inspired adhesive could be as common as Velcro.

A close-up of the robotic gripper, designed to grab objects in zero gravity using a gecko-inspired adhesive. | Image credit: Kurt Hickman

A team of researchers tested their gripper in multiple zero-gravity settings, including the International Space Station.

How a gecko-inspired robotic gripper can help clean up space debris

Jet engines can have up to 25,000 individual parts, making regular maintenance a tedious task that can take over a month per engine. Many components are located deep inside the engine and cannot be inspected without taking the machine apart, adding time and costs to maintenance. This problem is not only confined to jet engines, either; many complicated, expensive machines like construction equipment, generators, and scientific instruments require large investments of time and money to inspect and maintain.&nbsp;Researchers at Harvard University&rsquo;s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS) have created a micro-robot whose electroadhesive foot pads, origami ankle joints, and specially engineered walking gait allow it to climb on vertical and upside-down conductive surfaces, like the inside walls of a commercial jet engine. The work is reported in&nbsp;<a href="http://robotics.sciencemag.org/content/3/25/eaau3038" rel="noopener noreferrer" target="_blank">Science Robotics</a>.&ldquo;Now that these robots can explore in three dimensions instead of just moving back and forth on a flat surface, there&rsquo;s a whole new world that they can move around in and engage with,&rdquo; said first author S&eacute;bastien de Rivaz, a former Research Fellow at the Wyss Institute and SEAS who now works at Apple. &ldquo;They could one day enable non-invasive inspection of hard-to-reach areas of large machines, saving companies time and money and making those machines safer.&rdquo;The new robot, called HAMR-E (Harvard Ambulatory Micro-Robot with Electroadhesion), was developed in response to a challenge issued to the Harvard Microrobotics Lab by Rolls-Royce, which asked if it would be possible to design and build an army of micro-robots capable of climbing inside parts of its jet engines that are inaccessible to human workers. Existing climbing robots can tackle vertical surfaces, but experience problems when trying to climb upside-down, as they require a large amount of adhesive force to prevent them from falling.<iframe src="https://player.vimeo.com/video/303994124" frameborder="0" allowfullscreen="" class="fr-draggable" style="width: 772px; height: 430px;"></iframe>HAMR-E, created in collaboration with Rolls-Royce, is a micro-robot that uses electroadhesion to scale vertical, inverted, and curved surfaces, allowing it to explore spaces that are too small for humans. HAMR-E could one day be used to inspect jet engines and other complicated machines without requiring them to be taken apart. Credit: Wyss Institute at Harvard University.&nbsp;The team based HAMR-E on one of its existing micro-robots,&nbsp;<a href="https://wyss.harvard.edu/technology/versatile-ambulatory-microrobots/" target="_blank">HAMR</a>, whose four legs enable it to walk on flat surfaces and swim through water. While the basic design of HAMR-E is similar to HAMR, the scientists had to solve a series of challenges to get HAMR-E to successfully stick to and traverse the vertical, inverted, and curved surfaces that it would encounter in a jet engine.First, they needed to create adhesive foot pads that would keep the robot attached to the surface even when upside-down, but also release to allow the robot to &ldquo;walk&rdquo; by lifting and placing its feet. The pads consist of a polyimide-insulated copper electrode, which enables the generation of electrostatic forces between the pads and the underlying conductive surface. The foot pads can be easily released and re-engaged by switching the electric field on and off, which operates at a voltage similar to that required to move the robot&rsquo;s legs, thus requiring very little additional power. The electroadhesive foot pads can generate shear forces of 5.56 grams and normal forces of 6.20 grams &ndash; more than enough to keep the 1.48-gram robot from sliding down or falling off its climbing surface. In addition to providing high adhesive forces, the pads were designed to be able to flex, thus allowing the robot to climb on curved or uneven surfaces.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1569985592337-HAMR-E-whole_body-wPenny.jpg" style="width: 567px;" class="fr-fic fr-dib">HAMR-E is small but mighty, and could one day carry instruments and cameras to inspect small spaces. Credit: Wyss Institute at Harvard University&nbsp;The scientists also created new ankle joints for HAMR-E that can rotate in three dimensions to compensate for rotations of its legs as it walks, allowing it to maintain its orientation on its climbing surface. The joints were manufactured out of layered fiberglass and polyimide, and folded into an origami-like structure that allows the ankles of all the legs to rotate freely, and to passively align with the terrain as HAMR-E climbs.Finally, the researchers created a special walking pattern for HAMR-E, as it needs to have three foot pads touching a vertical or inverted surface at all times to prevent it from falling or sliding off. One foot releases from the surface, swings forward, and reattaches while the remaining three feet stay attached to the surface. At the same time, a small amount of torque is applied by the foot diagonally across from the lifted foot to keep the robot from moving away from the climbing surface during the leg-swinging phase. This process is repeated for the three other legs to create a full walking cycle, and is synchronized with the pattern of electric field switching on each foot.When HAMR-E was tested on vertical and inverted surfaces, it was able to achieve more than one hundred steps in a row without detaching. It walked at speeds comparable to other small climbing robots on inverted surfaces and slightly slower than other climbing robots on vertical surfaces, but was significantly faster than other robots on horizontal surfaces, making it a good candidate for exploring environments that have a variety of surfaces in different arrangements in space. It is also able to perform 180-degree turns on horizontal surfaces.HAMR-E also successfully maneuvered around a curved, inverted section of a jet engine while staying attached, and its passive ankle joints and adhesive foot pads were able to accommodate the rough and uneven features of the engine surface simply by increasing the electroadhesion voltage.<blockquote><figure class="quote">This iteration of HAMR-E is the first and most convincing step towards showing that this approach to a centimeter-scale climbing robot is possible, and that such robots could in the future be used to explore any sort of infrastructure, including buildings, pipes, engines, generators, and more<figcaption>ROBERT WOOD</figcaption></figure></blockquote>The team is continuing to refine HAMR-E, and plans to incorporate sensors into its legs that can detect and compensate for detached foot pads, which will help prevent it from falling off of vertical or inverted surfaces. HAMR-E&rsquo;s payload capacity is also greater than its own weight, opening the possibility of carrying a power supply and other electronics and sensors to inspect various environments. The team is also exploring options for using HAMR-E on non-conductive surfaces.&ldquo;This iteration of HAMR-E is the first and most convincing step towards showing that this approach to a centimeter-scale climbing robot is possible, and that such robots could in the future be used to explore any sort of infrastructure, including buildings, pipes, engines, generators, and more,&rdquo; said corresponding author Robert Wood, Ph.D., who is a Founding Core Faculty member of the Wyss Institute as well as the Charles River Professor of Engineering and Applied Sciences at SEAS.&ldquo;While academic scientists are very good at coming up with fundamental questions to explore in the lab, sometimes collaborations with industrial scientists who understand real-world problems are required to develop innovative technologies that can be translated into useful products. We are excited to help catalyze these collaborations here at the Wyss Institute, and to see the breakthrough advances that emerge,&rdquo; said &nbsp;Wyss Founding Director Donald Ingber, M.D., Ph.D., who is also the&nbsp;Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children&rsquo;s Hospital, and Professor of Bioengineering at SEAS.

HAMR-E uses electroadhesive pads on its feet and a special gait pattern to climb on vertical, inverted, and curved surfaces, like the inside of this jet engine. Credit: Wyss Institute at Harvard University

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