EXTENDING INPUT RANGE THROUGH CLUTCHING : ANALYSIS, DESIGN, EVALUATION AND CASE STUDY

Abstract

Most input devices can only express a limited range of values when users perform a single action. Only few devices, such as the mouse, permit users to extend device input range through clutching. This thesis presents a general systematical analysis and design approach for clutching techniques extending the range of input streams. Firstly, it analyses the nature and cause of clutching, operation stages in clutching and examines their relationships. The analysis showed that the sequential relationship and paired relationship among stages decided the design focus, order and constraints. Secondly, to design clutching, the thesis researches how external factors affect the design of operation stages. We found that system capability and application task work together to narrow down the design options. Thirdly, two digital pen studies exemplifies how our design approach can produce range extension in the pen¿ tilt and pressure input stream. These two studies showed that when design clutching, finding a single winning technique might not be feasible. Designers need to select a few winning candidates for different contexts. Based on all three, we propose a set of clutching design guidelines for a suite of input streams and tasks. Finally, we provide an early validation in a design case study with 8 expert designers showing that our analysis of clutching and design approach can help other designers to understand clutching better and support their clutching design for different input streams.