Watch: New 'WristWhirl' smartwatch can be operated with wrist movements

Scientists have developed a new smartwatch that can be operated with wrist movements and gestures, allowing users to control the device even when their hands are not free - such as while carrying groceries or holding a bus handle.

WristWhirl, the smartwatch prototype, uses the wrist wearing the watch as an always-available joystick to perform common touchscreen gestures with one-handed continuous input.

"While other studies have explored the use of one-handed continuous gestures using smartwatches, WristWhirl is the first to explore gestural input," said Xing-Dong Yang, assistant professor at Dartmouth College in the US.

"Technology like ours shows what smartwatches may be able to do in the future, by allowing users to interact with the device using one hand (the one that the watch is worn on) while freeing up the other hand for other tasks," Yang said.

To develop the prototype, researchers studied the biomechanical ability of the wrist by tasking a small group of participants to conduct eight joystick-like gestures while standing and walking.

Participants wore the watch on their left wrist and were asked to use their wrist to make four directional marks similar to flicking a touch screen, and four free-form shapes, such as a triangle.

They were asked to make these gestures with their hand up in front of their body during which they could see the gesture being drawn on the watch's screen, and with their hand down alongside their body.

They were able to make directional marks at an average rate of half a second and free-form shapes at an average rate of about 1.5 seconds.

Visual feedback appeared to slow participants down, as they were slowest at performing the tasks when their hand was out in front of them and fastest when their hand was down alongside their body.

To measure the accuracy of the free-form paths drawn using WristWhirl, researchers used the USD 1 gesture recogniser and found that it was able to recognise the marks with a 93.8 percent accuracy as compared to 85 percent accuracy by three human inspectors.

WristWhirl was built from a 2" TFT display and a plastic watch strap augmented with 12 infrared proximity sensors and a Piezo vibration sensor placed inside the wrist strap, which is connected to an Arduino DUE board, a type of microcontroller board.

Researchers created a gesture shortcuts app which allowed users to access shortcuts by drawing gestures.

They also developed a music player app which allowed users to scroll through songs through wrist-swipes and play a selected song by double tapping the thumb and index fingers.

A map app was implemented for which 2D maps could be panned and zoomed depending on where the watch was held in relation to one's body.

A game input, which often requires continuous input was also tested, for which Tetris was played using a combination of wrist swipes, wrist extension and wrist flexion.