Knitting with the fabric of space and time © Morphing Matter Lab, Human-Computer Interaction Institute, School of Computer Science, Carnegie Mellon University

Thanks to 4D knitting, cuddly soft toys are getting a robotic upgrade.

Lea Albaugh at Carnegie Mellon University in Pittsburgh, USA and colleagues have used knitting machines to create moving children’s toys and other objects.

The knitted items include a toy rabbit that gives hugs when pressed in the stomach, a jumper with a self-moving sleeve, and a lampshade that changes shape.


Silk strands are knitted into the fabric as part of the process. The strands function as tendons, enabling the objects to move in certain ways when they are pulled, such as curving or forming an S-shaped bend. A twisting motion, for example, occurs if the tendon is knitted diagonally into the object.

The team call the approach 4D knitting, with the expansion and contraction of the knitted loops adding the fourth dimension of time to the 3D objects.

The approach could be used to make cost-effective wearables and soft robots.

The wide availability of fabrics, including the choice of a wide variety of types and colours, makes it an ideal material for soft robots, says Albaugh. “There’s a wide range of motion types you can get out of soft robotics that can be friendly or silly,” she says, meaning they are ideal for children’s toys.

The team also experimented with conductive yarn, which could be knitted into objects to add smart sensors that can detect stretch or touch. They incorporated a conductive patch on the knitted rabbit’s belly.

Albaugh used a computer program to design the objects, breaking them down into horizontal (such as the rabbit’s arms) and vertical (its ears and legs) moving parts.

Industrial knitting machines are fast and reliable, she says. “It’s not just something that factories can use to make 6,000 of the same pair of gloves. It’s actually an incredibly flexible process that – if the software were better – would be able to make one-off items that are detailed at the stitch-level.”

The research was presented this week conference on Human Factors in Computing Systems in Glasgow.