Nature Inspires Professor Girish Krishnan?s Research in Soft Robotics

Emily Scott

An elephant’s soft trunk, a snake winding its body around a branch, a tree’s resistance to storms — these are some of the aspects of nature that inspire assistant professor Girish Krishnan’s research in bio-inspired design and soft robotics.

“My aim right now is to look at the fundamental mechanisms behind nature’s functionality and translate them as best as we can, within the engineering constraints, to modern engineering products,” he said.

Though at the time he had already completed his bachelor’s in mechanical engineering from the R.V. College of Engineering in India, Krishnan’s fascination with engineering didn’t begin until he transitioned to graduate school. He first completed his masters in engineering at the Indian Institute of Science and then completed his doctorate in mechanical engineering at the University of Michigan, Ann Arbor.

“My choice of pursuing engineering further after my bachelor’s is testimonial of my interest in engineering,” he said. “This primarily happened when I worked for a couple of companies, and I could see how concepts that we learned translated into making products and helping people in day-to-day life.”

From there, Krishnan knew he wanted to use his skills to make a difference in the more personal aspects of people’s lives, such as assisting disabled persons or preventing disease and injuries.

Initially, his main interest was in small systems, those that cannot be seen by the naked eye.

“From there, I started looking at trends between nature and engineering, the similarity there,” he said. “I tried to incorporate some of those aspects into my research, and that’s how my research has evolved.”

After completing his PhD, Krishnan applied for his current position with ISE. “I knew the previous history of this department was very design-centric, very systems-centric, and that prompted me to apply,” he said.

Since he was hired in 2013, Krishnan has advanced his research through his laboratory, taught courses in design, reliability, and flexible mechanisms, and won a National Science Foundation Career Award, a prestigious honor.

Through his research, Krishnan hopes to find a way to translate the features of nature into products that help people in their everyday lives.

“If you see some plant and animal structures, they are lightweight, reliable,” he said as an example. “In areas with tornadoes, you see buildings that collapse, but trees and plants still are not yielding or breaking as much.”

One particular translation he has been working on has been in the area of soft robotics.

Soft robotics is exactly like it sounds — instead of using hard, rigid materials such as metal, it uses skin-like, flexible, or even fluid components. The advantage of soft robotics is the fact that the materials used are sturdy and strong, yet moveable and incapable of injuring someone.

Soft robotics can be utilized to make personal robots, which could be anything from robots assisting in taking care of the elderly and disabled, to wearable robots that would allow users to perform specific tasks.

Bill Gates, co-founder of Microsoft, forecasted in a 2006 article for Scientific American magazine that in the near future, personal robots will be in every home. In the article, he stated that he “...can envision a future in which robotic devices will become a nearly ubiquitous part of our day-to-day lives.”

“For this, there has to be a fundamental change in the way they are made,” Krishnan said. “You can’t make them out of rigid materials … it’s still a block of metal, it can hurt you.”

That’s where robotics meets bio-inspired design in the creation of soft robotics, with parts that resemble something like an elephant’s trunk or a snake’s body.

“My work right now is to evolve, mature, and investigate engineering concepts that can enable these safe, personal robots in the next 10 to 15 years,” Krishnan said.

He initially became involved in the field of soft robotics as a result of his interest for being in step with leading new technologies.

“Technology will always progress, however, the fundamentals will remain the same,” he explained. “There is a lot of research these days on technology that can aid [people], but they are fundamentally limiting.”

In order to bring those fundamentals into the light, Krishnan suggests we look to concepts of nature.

“Maybe nature has better ideas,” he said — and he is quick to point out that not every aspect of nature will work. “But you can get inspired by how nature works and use that inspiration to make unprecedented advancements in technology.”

Soft robotics may also bring to mind the Disney movie “Big Hero 6,” which features an inflatable personal healthcare assistant robot called Baymax.

Krishnan said the idea of Baymax is indeed realistic. While the creation of this character was influenced by Carnegie Mellon University’s inflatable robotic arm, the projects within soft robotics that Krishnan and his research laboratory have pursued are related to smaller robots, such as their pneumatic arm sleeve.

The sleeve is designed specifically for children who use crutches. Krishnan explained how using crutches causes the entirety of the child’s body weight to be concentrated on their wrist, resulting in problems such as posture imbalances, wrist injuries, or even carpal tunnel syndrome.

Using an inflatable device, which inflates only when it is in use, the pneumatic arm sleeve allows the crutch to provide pressurized air into the sleeve, thus bearing the weight load to the entire arm instead of just the wrist.

Another creation he and his laboratory have made are applications called fiber reinforced elastomeric enclosures, which Krishnan said have a structure similar to an earthworm, having stretchable skins reinforced by fibers.

“You can think of them as laced with inextensible fibers, which, when pressurized, can yield some different motion characteristics that one cannot reproduce with existing mechanisms,” he said.

In theory, they are creating an active rope that will act similarly to the way a snake wraps itself helically around a branch.

“You could think of a rope that knots all by itself and holds an object; there is no such rope like that right now,” he said. “These are the kinds of advancements that we aim to obtain, to realize, at the end of our research.”

He and his laboratory have also shown progress in the creation of an entirely inflatable robot. It utilizes pressurized air to perform simple tasks on factory floors and can be reduced to the size of a balloon when the air is pushed out of it.

“It is extremely cost effective; the entire robot and its controls cost less than $100,” Krishnan said. “It doesn’t use electricity or any expensive actuators; all it requires is pressurized air, which most factories usually have in abundant fashion.”

He said this may revolutionize the niche area of factory automation that requires human interaction and the ability to repeat tasks, but not as much precision.

In addition, Krishnan hopes to expand his research further into the area of additive manufacturing, using tools such as 3D printing and rapid prototyping. He said using additive manufacturing to create applications such as the pneumatic arm sleeve would have many benefits.

“We overcome the boundaries of geometry, of materials,” he said. “We can print more, in any fashion we want, and can even custom make it.”

The research laboratory that Krishnan advises, the Monolithic Systems Lab, consists of five graduate students that work in different aspects of the creation process that range from theoretical to practical.

Together they strive to reach a balance between serendipity and structure. To Krishnan, this means coming up with ideas and then refining them with the scientific and engineering techniques and principles that are the foundation of their work.

“Most of what we have obtained is through random searching, but that’s not all we do,” Krishnan explained. “We have some kind of a structure behind the madness too.”

Often these methods will lead to breakthroughs and advancements that Krishnan said he is often amazed by.

“The students here are really good,” he said. “I feel blessed to work with them.”

Though the laboratory has seen progress in its innovative projects, they have to manage being in a field that has no set guidebook.

“It’s not something that you can find a whole lot of literature on, so there is no one to guide us when we hit a roadblock,” Krishnan said.

When they hit these roadblocks, he said they often ask themselves if they’ll continue in their initial line of thought or transition to a new one. Motivating his students to push on past these conflicts is just part of the challenge for Krishnan in his leadership role.

“It can get pretty lonely along the way,” he said, “but it’s our eventual realization of the technology that actually guides us.”

He described this eventual physical realization — seeing what they’ve created and seeing it work — as the most enjoyable part of his research and the driving force behind his the laboratory.

Aside from his research, Krishnan teaches courses in design, the theory of reliability, and flexible mechanisms, which relates to his research.

Krishnan said he has received self-assurance since receiving a National Science Foundation (NSF) Career Award, a prestigious honor and form of academic backing which he described as “one of the greatest jump starts that an assistant professor can get.” To him, it is a confirmation that his research and line of thinking are valid. He is now one of the nine ISE faculty that have received the award.

Looking forward, Krishnan aims to continue making developments with his projects.

His main goals are to translate technology such as wearable robots and to have people realize how useful these products can be so they can eventually become commercialized.


Monolithics Systems Lab team, 2015.
Monolithics Systems Lab team, 2015.


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