Industrial Electronics

Video: Knitted objects with moving parts could be the future of soft robots

03 May 2019

Plush toys could hold the key to future soft robots. Source: Carnegie Mellon University Plush toys could hold the key to future soft robots. Source: Carnegie Mellon University

Researchers from Carnegie Mellon University have created plush toys and other knitted objects that are actuated by tendons through controlled knitting machines.

The method for creating the plush toys may someday be used to make cheap soft robots and wearable technologies.

The knitting machines make it possible to create objects in their desired shapes and with tendons already embedded. The objects are stuffed and the tendons are then attached to motors. The tendon-embedding technique allowed for toys that can give hugs when poked in the stomach and even a sweater with a sleeve that moves on its own.

While the objects created are conceptual, the method could one day be expanded to more serious applications, researchers said.

"Soft robotics is a growing field," said Lea Albaugh, a Ph.D. student at Carnegie Mellon University who led the project. "The idea is to build robots from materials that are inherently safe for people to be near, so it would be very hard to hurt someone. Actuated soft components would be cheap to produce on commercial knitting machines.”

Using this type of system could allow for haptic interfaces to be put into chairs or backpacks that open autonomously.

Knitting machines are widely used but generally require a lot of programming for each garment. The CMU research would automate the process, making it easier to use in mass production machines to produce customized and one-off designs.

The method allows for embedding tendon paths horizontally, vertically and diagonally in fabric sheets and tubes. The combination with the orientation can produce a variety of motion effects such as bending, twisting and asymmetric bends.

A number of tendon materials can be used including polyester-wrapped quilting thread, pure silk yarn and nylon monofilament. These techniques also allow for sensing capabilities to be added to the objects, making it possible to sense the direction in which the object is being bent or twisted. Capacitive touch sensing and strain sensors could detect if a swatch is stretched.

While 3D printing is already being used to make customized, actuated objects and robotic components, materials are often hard to find. Computationally controlled knitting has the potential to expand the possibilities and make this process more people-friendly.

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