Gesture Keyboard - User centered design of a unique input device for Indic

Scripts

Ashish Krishna1, Rahul Ajmera1

Sandesh Halarnkar and Prashant Pandit

Human Factors International

HP labs

4th Floor, Chemtex House

24, Salarpuria Arena,

Hiranandani Gardens

Hosur Main Road, Adugodi,

Mumbai – 400 076

Bangalore, India

{ashish.krishna, rahul.ajmera}@hp.com

{sandesh.halarnkar,

1 Currently at HP labs

prashant.pandit}@hp.com

 

Abstract

Indic text input presents a unique challenge in the field of keyboard design because of the number of standalone characters, conjuncts, matras, and symbols. It poses a huge challenge to the HCI practitioners to accommodate the humongous array of Devnagari characters in a keyboard. Solutions for input in Devnagari scripts using a physical keyboard have been around for a while but none of them have emerged as a standard mechanism due to several usability related concerns. In this paper we have described the design of a new gesture based keyboard, which has a dual input mode 1. Gesturing 2. Tapping. The “gesture keyboard” concept is based on partial hand writing recognition as well as touch-typing paradigms. Conceptually, it is a stylus sensitive keypad that supports tapping for getting the base consonants and some symbols, while it also recognizes handwritten matras as per handwriting recognition methods. This paper also reports the findings of the user study, which was carried out to find the optimum sizes of the keys and layouts.

1 Keywords

Devnagari text entry, Gesture Keyboard (GKB), Matras, Modifier, Syllable, IMEs

2 Introduction

Given the well-understood challenges of achieving high accuracy with recognition of natural handwriting and dealing with the great variability in writing styles, a number of alternative schemes (generically called Input Method Environments or IMEs) have been developed for English and some Oriental scripts. Some of these are based on development of simplified gestures (e.g. Uniscript and Graffiti for English), others are based on interactively arriving at the intended character using partial handwriting input or other cues from the user.

This new keyboard introduces a paradigm shift in text inputting methods. We have developed a prototype for Devnagari, which takes best of both worlds; it takes cues from handwriting recognition (matras formation) and touch-typing (base characters). The new design has all the base consonant keys and the user is required to make a Matra (a gesture) on top of it, to make a syllable. Thus significantly reducing the need to hunt and peck and leading to quick learnability, retention and reduced hunting load.

The Gesture Keyboard is not presented as an alternative to the conventional English keyboard but has been proposed as a peripheral input device. The user would have an additional device (GKB) connected to his workstation along with the regular ASCII English keyboard and a mouse as shown in Figure below.