Virtual reality promises an escape into immersive visual environments, rendered in incredible detail. The one problem, though, is getting users to actually feel anything.

Imagine, for instance, virtually feeling your way along the walls of a maze, or feeling the contours of a piece of furniture at a shop, or even giving a virtual character a high-five.

“Elements such as walls, furniture and virtual characters are key to building immersive virtual worlds, and yet contemporary VR systems do little more than vibrate hand controllers,” says Chris Harrison, assistant professor at CMU’s Human-Computer Interaction Institute.

A Carnegie Mellon University student researcher thinks she has an answer: strings.

“So the mechanism, if you can imagine, is strings attached to different parts of your hand: your fingertips, your palm and your wrist,” says Cathy Fang, who will graduate from CMU next month with a joint degree in mechanical engineering and human-computer interaction.

“As the user extends their hand and arm out and tries to touch a virtual wall, or furniture, in front of them — in real life, they should feel resistance in front of their hand, because there’s something there. In virtual reality, there’s nothing that’s actually resisting the fingers, and the hand is going through it. Our mechanism basically just stops the hand at the virtual collision with the virtual object, and pulls the fingers back so that the user can feel some resistance there.”

Strings have been tried by others, but motors are typically used to control them. Fang’s approach differs — instead, they developed a system using low-tech spring-loaded retractors, like you’d find in a fishing reel, keychain or ID badge. They use a ratchet mechanism that can be quickly locked with an electrical latch. Springs, not motors keep the strings tight.

“We believe that motors are much heavier and can use a lot of power, and heat up very quickly,” says Fang. “Our mechanism is really small and can be worn on the shoulder. It’s also very energy efficient.”

“We also tried the motor approach. It turns out that it’s louder and heavier and consumes a lot of energy. You have to keep it running to rewind the string. Our spring-based mechanism requires very little power.”

The entire device, called “Wireality,” weighs less than 10 ounces. It uses simple, off-the-shelf parts, and Fang estimates it could be mass-manufactured for about $35.

The research paper that Fang and her team developed was named a best paper by the Conference on Human Factors in Computing Systems, which was canceled due to the coronavirus pandemic. The paper has instead been published within the conference proceedings in the Association for Computing Machinery’s digital library. Co-authors include Harrison, Fang, Robotics Institute engineer Matthew Dworman and doctoral student Yang Zhang.

In a time when physically visiting a lot of places is difficult or impossible, this offers the chance to get closer to the real thing.

“This could be an interesting way to explore things when you physically can’t be in those spaces, like a museum,” says Fang. “Imagine a statue in front of you that you can touch and feel the surface, and how it changes when you feel it from different angles.”

“You might also use it to shop in a furniture store,” she adds.

A video of the device in action can be seen below and here.