Researchers Develop Foldable Haptic Actuator for Mixed Reality Applications

Touch&Fold is worn on a user’s fingernail and renders touch in MR without preventing them from also touching real objects.

Cabe Atwell
19 days agoSensors / Robotics

Researchers from the University of Chicago have developed a foldable haptic feedback device that allows users to touch objects in mixed reality environments, then gets folded back onto the user’s nail when touching objects in the real world. Known as Touch&Fold, the end-effector also features a linear resonant actuator that lets the unit touch virtual objects and their textures. Sure, many haptic devices on the market enable users to interact with objects in the virtual world, such as controllers and gloves, but none provides the ability to interact with objects in both worlds and “feel” them at the same time.

The Touch&Fold works in conjunction with Microsoft’s HoloLens 2 headwear, which displays MR content and tracks user’s hands with depth cameras. The device attaches to the user via double-sided tape. The folding mechanism design uses a rack and pinion to fold and unfold a thin plastic sheet over the tip of the finger, which is actuated by a DC motor to drive a linear resonant actuator back and forth over the finger.

A force sensor (FSR 400, Interlink Electronics) and a photo interrupter (SG-105F, Kodenshi) are embedded in the device to close the control loop by acting as limit switches. The force sensor also doubles as a feedback signal for fine-tuning the amount of pressure applied to the fingerpad. The combo allows the device to create not only pressure but measures the applied force as well. The Touch&Fold takes about 92 milliseconds to actuate, which provides low-frequency vibrations on the finger contact points. Using the haptic feedback device lets wearers feel on-body surfaces, a transition between the virtual and physical, and connect with more complex objects.

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