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Expressive typing: a new way to sense typing pressure and its applications

In this paper, we propose a new way for measuring key typing pressure when using off-the-shelf laptop computers. Accelerometers embedded in laptop computers to protect hard discs from sudden motion are becoming very common. This paper explores the concept of utilizing this accelerometer for sensing non-verbal aspects of key typing, such as key typing pressure. This possibility enables a wide variety of pressure-sensitive user interfaces through the use of software without requiring any additional hardware/sensors. Such software can be distributed easily to a substantial number of potential users. To confirm the feasibility of this idea, we compared typing finger velocities (obtained by high-speed camera images) with sensor data from an accelerometer embedded in a laptop computer. We then confirmed that there is a clear correlation between these two sets of data. We also investigated differences in typing pressure patterns among different users. By combining keystroke speeds and typing pressure, we found it is possible to distinguish among users. This feature can be used for security purposes such as preventing a laptop computer from being used by non-owners. We also present possible application ideas such as rich text expression, new types of user interface elements, and authentication.