A cost-effective three-in-one personal digital assistant input control

We attach an inexpensive pressure sensor to the side of a personal digital assistant and use it as three input devices at once. Users can squeeze the device to provide near-continuous input to applications. At the same time the drivers interpret a sudden full squeeze as the push of a virtual button. A user’s sudden pressure release while squeezing is detected as the push of a second virtual button. We briefly describe our hardware and signal processing techniques. The remainder of the writing describes an experiment that explores whether users can cope cognitively with the 3-in-1 control. We compare against a three-control setup consisting of a jog wheel and two physical buttons. We show that the three-in-one control enables a 13% faster reaction time over the three-control one, but that the three-in-one control suffers a 4% penalty in the accuracy of users choosing between the two buttons in response to cues from an application. We show that a good choice of application cue is more important for assuring accuracy in the 3-in-1 than in the more traditional set of separate controls. r 2004 Elsevier Ltd. All rights reserved.