Low-Cost Power Efficient Haptic Device for VR Invented at Carnegie Mellon
Andrew Wheeler posted on May 06, 2020 |
Haptic feedback developed by innovative string placement, Leap Motion and rachet mechanisms.
(Image courtesy of Carnegie Mellon University.)
(Image courtesy of Carnegie Mellon University.)

Virtual reality is at its core an attempt to create an immersive digital experience that mimics physical reality. This means replicating how all our five senses interact with the physical world. While virtual reality does a decent job of immersing our eyes and ears into the digital world, touch is a different story, and taste and smell are generally out of the question for the technology.

There are many haptic devices that are available to address the lack of touch in virtual environments, and a new device developed at Carnegie Mellon University uses some interesting mechanics to balance the equation of incorporating touch while keeping the hardware that enables this sense to be lightweight. Bulky hardware is always an issue with virtual reality systems.

The device from Carnegie Mellon uses strings attached to the hands and fingers to mimic the feeling of resistance that objects and obstacles present us with all the time in physical reality. It was created by Cathy Fang, a soon-to-be graduate of the university, with a double major in mechanical engineering and human-computer interaction.

The device is shoulder mounted and features spring-loaded strings for weight reduction and low impact on battery energy—another important part of the virtual reality system’s balancing equation. Fang’s device is also low-cost when compared with computer electronic options.

How It Works

The system’s strings lock up when a hand encounters an obstacle, such as a virtual wall, and performs similar but more complex locking when a hand “holds” a virtual object, giving resistance at the appropriate contours of an object’s geometry. The haptic device locks when you run your hands down a railing around the virtual railing using a dissimilar method to other haptic devices, which generally rely on stepper motors to simulate haptic touch.

Rather than stepper motors, Fang’s device uses a lightweight ratchet mechanism that quickly locks using very little electrical power. Using trial and error, many different types of strings and string placements were tested until Fang and her fellow researchers configured the following: one string attaches to each fingertip, one to the palm and one to the wrist. The springs, not motors, keep the strings taut. Fang’s haptic device senses proximity and “springs its trap” via a Leap Motion sensor. The Leap Motion senses when a user’s physical hand is closing in on a virtual object or obstacle, and the ratchet mechanisms run a sequence that fits around the virtual object, providing the appropriate resistance relative to the hand’s motion on a given virtual geometry.

Then, the latches release simultaneously with the hand

Bottom Line

The device weighs less than 10 ounces, and Fang and her fellow researchers from Carnegie Mellon estimate that the cost per unit would equal less than $50.

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