A-coord input: coordinating auxiliary input streams for augmenting contextual pen-based interactions.

The human hand can naturally coordinate multiple finger joints, and simultaneously tilt, press and roll a pen to write or draw. For this reason, digital pens are now embedded with auxiliary input sensors to capture these actions. Prior research on auxiliary input channels has mainly investigated them in isolation of one another. In this work, we explore the coordinated use of two auxiliary channels, a class of interaction techniques we refer to as a-coord input. Through two separate experiments, we explore the design space of a-coord input. In the first study we identify if users can successfully coordinate two auxiliary channels. We found a strong degree of coordination between channels. In a second experiment, we evaluate the effectiveness of a-coord input in a task with multiple steps, such as multi-parameter selection and manipulation. We find that a-coord input facilitates coordination even with a complex, aforethought sequential task. Overall our results indicate that users can control at least two auxiliary input channels in conjunction which can facilitate a number of common tasks can on the pen.