Instead of using a pen or a touch sensitive display, there are other possibilities to operate hand-held devices. We propose the idea of using tilt as the input method.
Sensing rotation of the device is much easier than sensing motions, by using small solid-state angular rate sensors (gyros). We can also use an electric inclinometer or a compass to assist the other sensors. As these types of sensors become used in other devices, we believe that the tilting interface becomes much more practical. Unlike pen interfaces, tilting allows single hand operation (i.e., only one hand is required to hold and operate the device). This feature is particularly useful for very small electronic devices such as pagers.
Tilting pie menu
A map browser using tilting interface
Some other links related to "Tilting UIs" (appeared after our initial publications and patents).