TPad Fire: Surface Haptic Tablet (2013)

Touchscreens have been a boon to computer interaction, offering flexibility to the designer and naturalness to the user. Surface haptics has the potential to enhance touchscreen interactions by increasing communication, improving performance, and making the interactions feel more real to the user. The vast majority of research on haptic surfaces has been done with vibrotactile devices. While vibration-based approaches have been successful to the point of being widely commercialized, force-based haptics allows additional interaction possibilities that may enhance realism and strengthen emotional engagement even further. These possibilities include the perception of weight, stiffness, resistance, and shape, and can aid in the performance of tasks such as target acquisition.

Variable friction technology is one method of producing force-based haptics. Our variable friction device (TPad) can control friction between the surface and the user’s fingertip through low amplitude, high frequency (ultrasonic) vibration of the surface. The highest friction state occurs when the vibration amplitude is zero (i.e., native friction of finger on glass), and the friction level steadily decreases as the vibration amplitude grows. Variable friction technology has gone through many iterations of hardware advances. However, the difficulty of building devices and their limited availability in the past has meant that researchers in the field of human-computer interaction have had few opportunities to develop novel applications.

The TPad Fire is the first product of the TPad Tablet Project. It is a variable friction surface integrated with a Kindle Fire™ tablet computer. The intent of the TPad Tablet Project is to spur research and design with force-based surface haptic interactions by creating an affordable, easy to use, and easily available platform.

Citation: Mullenbach, J., Shultz, C., Piper, A.M., Peshkin, M., and Colgate, J.E. 2013. TPad Fire: Surface Haptic Tablet. In Proceedings of the International Workshop on Haptic and Audio Interaction Design (HAID '13)