A new VR device developed at
Carnegie Mellon University uses multiple strings attached to the hand and
fingers to simulate the feel of obstacles and heavy objects. By locking the
strings when the user’s hand is near a virtual wall, for instance, the device
simulates the sense of touching the wall. Similarly, the string mechanism
enables people to feel the contours of a virtual sculpture, sense resistance
when they push on a piece of furniture or even give a high five to a virtual
character. Other researchers have used strings to create haptic feedback in
virtual worlds, but typically they use motors to control the strings. Motors
wouldn’t work for the CMU researchers, who envisioned a system both light
enough to be worn by the user and affordable for consumers. Instead of motors,
the team used spring-loaded retractors, similar to those seen in key chains or
ID badges.
They added a ratchet mechanism
that can be rapidly locked with an electrically controlled latch. The springs,
not motors, keep the strings taut. Only a small amount of electrical power is
needed to engage the latch, so the system is energy efficient and can be
operated on battery power. The researchers experimented with a number of
different strings and string placements, eventually concluding that attaching
one string to each fingertip, one to the palm and one to the wrist provided the
best experience. A Leap Motion sensor, which tracks hand and finger motions, is
attached to the VR headset. When it senses that a user’s hand is in proximity
to a virtual wall or other obstacle, the ratchets are engaged in a sequence
suited to those virtual objects. The latches disengage when the person
withdraws their hand.
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