Scientists have developed a new technology that enables smartwatches to recognise gestures such as taps and flicks as well as identify objects held in the user’s hand, making possible new types of interactions with wearable devices. Researchers at Carnegie Mellon University in the US discovered that a software upgrade that re-purposes the smartwatch’s existing accelerometer enables the device to detect and distinguish a variety of taps, flicks and scratches by the hands and fingers.
This function makes possible new applications that use common gestures to control the smartwatch and other objects connected through the internet of things, researchers said. By monitoring vibrations that occur when people hold objects or use tools, the smartwatch also would be capable of recognising objects and activities. It could even be used to help tune a guitar, with the smartwatch displaying the note transmitted as the guitarist plucks and adjusts each string.
“It’s as if you’re using your hand as a detection device. The hand is what people use to interact with the world,” said Gierad Laput, a PhD student in the Human-Computer Interaction Institute (HCII). The technology, dubbed ViBand, was developed by Laput and Robert Xiao, also PhD student at HCII, along with their adviser Chris Harrison, assistant professor at HCII. Normally, a smartwatch accelerometer is used to detect when a person lifts an arm so the screen can activate, or sometimes to count footsteps. To do so, the accelerometer only needs to take measurements about 100 times a second.
However, when researchers increased the sampling frequency to 4 kilohertz (kHz), they found it acted like a vibrational microphone. Rather than detecting sounds transmitted through the air, it couples with the body to detect bio-acoustic signals. “ViBand is not just a way to control your smartwatch. It enables you to augment your arm. It’s a powerful interface that is always available to you,” Harrison said. A ViBand-enabled watch can tell if someone is tapping on the forearm, the palm of the hand or the back of the hand. It can detect finger flicks, scratches and other motions.
It also can sense if a person is holding various mechanical and electrical tools, such as an electric toothbrush, power drill or handsaw. Each body tap, device or activity has distinctive bio-acoustic signals. To increase the frequency of the accelerometer’s sampling rate, the team developed a custom kernel – the core of the smartwatch’s operating system. That is the only modification required and can be performed as a software update.
The team developed several demonstration apps for ViBand, including the use of hand gestures in the area around then watch to control apps on the watch. Similar gestures may be used to control remote devices, such as lights or a TV or other appliances connected via the internet of things.