Vision-based force sensor for touch panel devices using built-in camera

We propose a novel input interface for touch panel devices that employs the built-in camera of the devices to measure multi-axis force information applied by a user. The user attaches the proposed interface, which consists of an elastic body and markers, to the built-in camera. The touch panel device can then detect force information applied by the user to the elastic body based on vision-based force sensor technology called GelForce. We implemented a prototype and confirmed that the proposed interface can measure 3-axis force. We then conducted user studies to verify that the proposed interface is acceptable to users of touch panel devices.