We propose and study a new input modality, WristWhirl, that uses the wrist as an always-available joystick to perform one-handed continuous input on smartwatches. We explore the influence of the wrist’s bio-mechanical properties for performing gestures to interact with a smartwatch, both while standing still and walking. Through a user study, we examine the impact of performing 8 distinct gestures (4 directional marks, and 4 free-form shapes) on the stability of the watch surface. Participants were able to perform directional marks using the wrist as a joystick at an average rate of half a second and free-form shapes at an average rate of approximately 1.5secs. The free-form shapes could be recognized by a $1 gesture recognizer with an accuracy of 93.8% and by three human inspectors with an accuracy of 85%. From these results, we designed and implemented a proof-of-concept device by augmenting the watchband using an array of proximity sensors, which can be used to draw gestures with high quality. Finally, we demonstrate a number of scenarios that benefit from one-handed continuous input on smartwatches using WristWhirl.
Interacting with current smartwatches often necessitates both hands for scrolling or gesturing. However, in many situations, two handed interactions may interrupt our current text. For example, when a user is riding a bike, he has to stop the bike to interact with the watch. There are also some similar situations when the other hand is occupied by daily activities, such as grabbing a handle on a bus, holding an umbrella in a rainy day, etc. Therefore, one-handed interaction with smartwatches can help our users to free one hand, which may be a good alternative in many situations.
This is our proof-of-concept prototype. We augmented 12 infrared proximity sensors along the watch strap. Each is composed of a pair of IR emitter and detectors. The proximity sensor operates at 940nm, distinguished its signal from visible light. We also attached a piezo vibration sensor inside the watch strap. Sensor can detect sound of the finger pinch propagating through the user’s skin so that user can use pinch to indicate start or end of the gesture.
We built four applications to demonstrate the possibilites of WristWhirl.
For more details, please check the application section in our video.
Selected Press Coverage
Wall Street Journal: A Smartwatch That Works With One Hand
Discovery’s Daily Planet: FLICK OF THE WRIST