Teensy 3.6-Powered PoCoPo Puts Motorized Pins in the Palm of Your Hand for VR Haptic Rendering

Researchers from the University of Tokyo have unveiled a handheld "shape display" designed to allow objects in virtual reality to be brought out into the real world: PoCoPo.

"We introduce PoCoPo, the first handheld pin-based shape dis-play that can render various 2.5D shapes in hand in real time," the team write in the paper's abstract. "We designed the display small enough for a user to hold it in-hand and carry it around, thereby enhancing the haptic experiences in a virtual environment. PoCoPo has 18 motor-driven pins on both sides of a cuboid, providing the sensation of skin contact on the user's palm and fingers."

The PoCoPo device measures 222x52x54mm (around 8.7x2x2"), and is designed explicitly for hand-held use — making it distinct from previous efforts like MIT's inForce, which was designed for desktop use. A DC motor is attached to each pin via worm gear mechanism, enabling it to push up against the user's hand in the shape of a touched virtual object. Control is handled by a Teensy 3.6 microcontroller, which can communicate with the host device via USB or Bluetooth connections, while spatial tracking is handled by an off-the-shelf Vive Tracker.

"We conducted two user studies to understand the capability of PoCoPo," the team explains. "The first study showed that the participants were generally successful in distinguishing the shapes rendered by PoCoPo with an average success rate of 88.5%. In the second study, we investigated the acceptable visual size of a virtual object when PoCoPo rendered a physical object of a certain size. The result led to a better understanding of the acceptable differences between the perceptions of visual size and haptic size.

"While there exist several limitations in the current implementation," the researchers admit, "we believe that PoCoPo provides a highly immersive and realistic experience in VR with the reproduction of haptic sensation in hand. In future work, we will further improve the performance of the handheld pin-based shape display, including the pin speed,display area, and resolution, to present many kinds of shapes to the entire hand."

The team's paper is available for download under open-access terms from lead author Shigeo Yoshida's website.