MIT soft robotic wearables image
Credit: MIT

World-renowned US technology university Massachusetts Institute of Technology (MIT) scientists have created a cutting-edge design and fabrication tool that is set to speed up the development process of smart assistive devices like wearable rehabilitative gloves or exoskeletons.

The MIT team created a robotic glove, which looks a bit like “banana fingers”, using the autonomous knitting tool to help people with limited dexterity more easily grip objects.

This advanced technology project is built around soft, pneumatic actuators, which use compressed air to power motion. With sensing capabilities, these actuators can be used in a wide variety of applications, such as assistive wearables, robotics, and rehabilitative technologies.

However, these devices typically require a manual design and fabrication pipeline, which results in a lot of trial-and-error cycles to see whether the designs will work.

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To tackle this issue, scientists from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) devised a scalable pipeline to computationally design and digitally fabricate soft pneumatic actuators called PneuAct.

PneuAct uses a machine knitting process, but this machine operates autonomously. A human designer simply specifies the stitch and sensor design patterns in software to programme how the actuator will move, and it can then be simulated before printing.

The textile piece is fabricated by the knitting machine, which can then be fixed to an inexpensive, off-the-shelf rubber silicone tube to complete the actuator.

The knitted actuator integrates conductive yarn for sensing, allowing the actuators to “feel” what they touch.

MIT scientists developed several prototypes spanning an assistive glove, a soft hand, an interactive robot, and a pneumatic walking quadruped. They used a combination of elastic and sensing stitches (with conductive yarn) that allows for programming bending of the devices when they are inflated, and the ability to incorporate real world feedback.

For example, the team used the actuators to build a robot that sensed when it was touched specifically by human hands, and reacted to that touch.

Learn more about PneuAct and how it can bring assistive devices to life in the video below:

The team’s assistive glove can be worn by a human to supplement finger muscle movement, minimising the amount of muscle activity needed to complete tasks and motions. This could hold a lot of potential for those with injury, limited mobility, or other trauma to the fingers.

The method can also be used to make an exoskeleton. To that end, the researchers made a sleeve that can help wearers bend their elbow, knee, or other body parts.

“Digital machine knitting, which is a very common manufacturing method in today’s textile industry, enables ‘printing’ a design in one go, which makes it much more scalable,” says Yiyue Luo, a MIT CSAIL PhD student and the lead author of a new paper about the research. “Soft pneumatic actuators are intrinsically compliant and flexible, and combined with intelligent materials, they’ve become a necessary force in many robots and assistive technologies — and rapid fabrication, with our design tool, can hopefully increase ease and ubiquity.”

One type of sensing the team incorporated was called “resistive pressure sensing,” where the actuator “sends” pressure. When fabricating a robotic gripper, it would try to grab onto something, and the pressure sensor would sense how much force was being applied to the object, and then it would try to see whether the grasp was successful or not.

The other type is “capacitive sensing,” where the sensor discerns some information on the materials that the actuator is getting in touch with.

Luo wrote the paper alongside Kui Wu, former MIT CSAIL PhD student, Spielberg, MIT postdoc Michael Foshey, and MIT professors Tomas Palacios, Daniela Rus, and Wojciech Matusik. They presented the paper at the ACM Conference on Human Factors in Computing Systems.

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