WrisText: One-handed Text Entry on Smartwatch using Wrist Gestures

Abstract

We present WrisText - a one-handed text entry technique for smartwatches using the joystick-like motion of the wrist. A user enters text by whirling the wrist of the watch hand, towards six directions which each represent a key in a circular keyboard, and where the letters are distributed in an alphabetical order. The design of WrisText was an iterative process, where we first conducted a study to investigate optimal key size, and found that keys needed to be 55o or wider to achieve over 90% striking accuracy. We then computed an optimal keyboard layout, considering a joint optimization problem of striking accuracy, striking comfort, word disambiguation. We evaluated the performance of WrisText through a five-day study with 10 participants in two text entry scenarios: hand-up and hand- down. On average, participants achieved a text entry speed of 9.9 WPM across all sessions, and were able to type as fast as 15.2 WPM by the end of the last day.

Publication
In Proceedings of the ACM Conference on Human Factors in Computing Systems (CHI’18)
Date

Motivation

Text entry is a common and important task in daily mobile life, comprising of approximately 40% of mobile activity. However, entering text on a smartwatch is challenging because of the small form factor and its wearable context. One of the most commonly observed problems is the need to use one or both hands for a task (e.g. driving or walking while holding an umbrella or shopping bags). This is cumbersome in the context of smartwatches, as a user is required to interrupt their ongoing task to enter text, which reduces the purposefulness of smartwatches, as they are predominantly valuable for accessing information while on-the-go.

How WrisText Works

WrisText is a one-handed text entry technique for smartwatches using the wrist’s joystick-like motion. With it, a user whirls the wrist of the same-side hand to strike directional marks to select keys on a circular keyboard on a smartwatch. To enter “you”, a user selects [YZAB] -> [ONML] -> [TUVWX] by striking the wrist N -> S -> W. The entered text and suggested auto-complete are shown on the screen.

Enter “Y” Enter “O” Enter “U” Select “YOU”

Prototype

Our hardware is similar to the one presented in WristWhirl. The device contains a Ticwatch 2 and a plastic watch strap augmented with 12 infrared proximity sensors (LITON LTE-301 & 302) placed approximately 0.4 cm apart from each other. We connected the sensors to an Arduino DUE microcontroller, which is connected to a laptop reading sensor data at a speed of 9600 Hz. Data is then sent and visualized on the Ticwatch 2 through Bluetooth. Pinch and rub is detected using piezo vibration sensors placed inside the wrist strap.

Prototype Sensors

Selected Press Coverage

EurekAlert: Dartmouth College brings smartwatch innovations to CHI2018

QUARTZ: The newest idea for smartwatch texting looks just like your old flip phone

Weather Science: Smartwatch Enters Text with Wrist Movements

Discovery’s Daily Planet: Replies from the wrist