Soft, but not weak

Real-life “soft robotics” aren’t that dissimilar from those explored in the hit movie "Big Hero 6"

When Chris Atkeson, a professor in CMU’s robotics and human-computer interaction institutes, saw “Big Hero 6” upon its release last November, he instantly recognized Baymax’s texture and shape. It was very similar to one from Atkeson’s own lab.

It wasn’t a coincidence. To prepare for “Big Hero 6,” co-director Don Hall visited Atkeson’s lab to get a glimpse of real-life robotics. “They sent him here for the same reason they sent the (California-based) animators of ‘Frozen’ out to Norway to see snow,” says Atkeson, “to examine what it looks like, how it moves.”

A particular inspiration to Hall was an inflatable robot arm developed in 2011 by Siddharth Sanan (CS’10,’13), who was then a doctoral student in the Robotics Institute working under Atkeson. Hall later told a Reddit forum that he “knew right then and there” that Sanan’s arm would provide the inspiration for Baymax, “because it would be the perfect huggable robot.”

Robot sidekicks are hardly new; think of Robby the Robot in “Forbidden Planet” or the refrigerator-like TARS and CASE from last year’s “Interstellar.” But Baymax is different. Instead of clanking limbs and unyielding metal skin, Baymax has a soft, inflatable body. He’s more Michelin man than C3-PO. And unlike movies that have depicted robots as industrial appliances or tools of war, “Big Hero 6” presents Baymax as a healthcare assistance robot. He looks upon Hiro, the human protagonist of the movie, as his patient.

Baymax doesn’t just mirror the CMU arm’s appearance but also its purpose—both were designed as home health aides. The real arm developed by Sanan can rotate on a pivot and move back and forth thanks to an “elbow.” Its claw-shaped “hand” can deliver a spoon, cup or washcloth to someone not equipped to grab such items his or herself. The softness of the arm makes it easy on the user’s skin.

While Baymax is fictional, research into “soft robotics” is very much a reality in Carnegie Mellon’s Robotics Institute. The idea behind many of the current research projects is the creation of machines that can be used safely and comfortably in very close proximity to humans, giving the elderly and disabled their own robot companions.     

Take, for example, the soft, artificial muscle actuators developed by Yong-Lae Park, an assistant professor in the Robotics Institute and founder of its Soft Robotics and Bionics Lab. The actuators are made of Kevlar fibers and silicone rubber and include sensors that allow them to “puff up,” contracting in certain directions in reaction to muscle movement. They could create a garment worn around an elbow, knee or other joint to bolster the strength of a disabled person.

In a similar vein are the soft artificial skin sensors developed by a research team headed by Park. The second “skin” is silicon rubber containing a tiny, embedded hydraulic channel for use in detecting body movements and contact with the wearer’s own skin. It could also be put on unresponsive patients and monitor them to ensure that an uncomfortable amount of pressure isn’t placed upon one part of the body, preventing bedsores. “It could be worn as a prosthetic or you could coat a whole bed with it,” Park says. It also could be used, with further improvements, to scrutinize the performance of an athlete, down to what muscles he or she tenses.

To interact in such close quarters with vulnerable people, soft robots also will need good judgment. Gripping the arm of a 70-year-old woman requires a different approach than grabbing a door handle. That’s an aspect of the real-life Baymaxes of the future that’s being explored by Sidd Srinivasa (CS’01,’05), Finmeccanica associate professor of computer science and founder of CMU’s Personal Robotics Lab.

“I would define a soft robot behaviorally, rather than by (its construction) material,” Srinvasa says. Even robots made of soft material, he jokes, have parts “that could whack you pretty hard.”

So instead of focusing solely on softer materials, designers of home assistance robots are trying to teach robots how to interact appropriately with human beings. To this end, Srinvasa’s lab is a kitchen setup, filled with coffee mugs, boxes of Pop-Tarts, cans of Campbell’s Soup and packages of Toffifay candy. He and his team spend hours testing his two trademark robots, the mobile Home Exploring Robot Butler, or HERB (made famous in a viral video produced by the makers of Oreo cookies), and the sedentary set of mechanical arms known as Assistive Dexterous Arms, or ADA, in opening these items and moving about the kitchen.

For these types of robots to significantly simplify the lives of the disabled, they have to become much “smarter,” Srinvasa says. Right now, using ADA to open a bottle of soda requires a dizzying array of maneuvers on a joystick and takes several minutes. Much development must occur before a machine such as ADA could help a disabled veteran who has lost the use of his arms to pick up his newborn.

“We need to change the paradigm so that robots are human aware, that they understand what is in their environment and can react gracefully to it,” Srinvasa says. “That will require major advances in robotics.”

Soft robots also have applications outside of close collaboration with humans. In fact, one of Atkeson’s soft robots is designed to go somewhere where no human should be—in proximity to a bomb. AIRArm, created in collaboration with the iRobot Corporation, is an inflatable claw that extends from a mini-tank. It can be used to carefully pick through locations where there might be an explosive. Such soft robots might be able to bend and extend into small areas where a metallic limb wouldn’t fit, Atkeson says.

While Baymax’s cute quips and feelings of friendship toward Hiro are products of screenwriters, Atkeson says the fictional android hit on a few truths of soft robots expected to interact intimately with humans. Like many roboticists, Atkeson has bristled at comparisons between his projects and the androids of Hollywood. Data on “Star Trek: The Next Generation,” the Terminator and even Wall-E have all “created expectations that are impossible to meet and don’t have much to do with current robotics.”

Atkeson doesn’t have that antipathy toward Baymax, which depicts the real-life goal being pursued by so many researchers—robots that help, not hurt. In December 2014, he wrote a commentary for CNN’s website entitled, “Why I Want To Build Personal Health Care Companions Like Baymax.” He even purchased the domain,

“I loved the movie, and I thought it was very pro-technology and pro-robot,” Atkeson says. “I thought it showed a robot that wanted to help people, which was such a relief after seeing them trying to kill people so many times.”

—Nick Keppler is a Pittsburgh-based freelance writer and a frequent contributor to The Link who also writes for websites such as and for alternative newsweeklies around the United States.

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