Hand Range Interface: Information Always At Hand With A Body-Centric Mid-Air Input Surface

Most interfaces of our interactive devices such as phones and laptops are flat and are built as external devices in our environment, disconnected from our bodies. Therefore, we need to carry them with us in our pocket or in a bag and accommodate our bodies to their design by sitting at a desk or holding the device in our hand. We propose Hand Range Interface, an input surface that is always at our fingertips. This body-centric interface is a semi-sphere attached to a user's wrist, with a radius the same as the distance from the wrist to the index finger. We prototyped the concept in virtual reality and conducted a user study with a pointing task. The input surface can be designed as rotating with the wrist or fixed relative to the wrist. We evaluated and compared participants' subjective physical comfort level, pointing speed and pointing accuracy on the interface that was divided into 64 regions. We found that the interface whose orientation was fixed had a much better performance, with 41.2% higher average comfort score, 40.6% shorter average pointing time and 34.5% lower average error. Our results revealed interesting insights on user performance and preference of different regions on the interface. We concluded with a set of guidelines for future designers and developers on how to develop this type of new body-centric input surface.