Most modern input devices demand a high level of fine-motor skills from its users. This approach we developed during the course of the IAAA project is aimed at minimizing the precondition of fine-motor skills and instead using the shaking of limbs (e.g., an arm) as a way to interact with a computer-based system.
Many common interaction methods presume a user to have strong fine motor skills. In case these skills are not or only with deficits present, interaction may become difficult. These considerations led to our prototypes for pressurebased interaction – we found out in earlier user tests that many people with limited horizontal hand movement could control movement along the vertical axis much better. Additionally, our user tests led to the idea of hand or arm shaking as interaction method, especially for people with only partial remaining hand (or foot) functionality like ALS patients where shaking the hand or waving are often the only movements possible. Both wearable devices used by our prototypes offer sensors that help to discover and analyze shaking movement in general and also allow for distinction between different levels of shaking intensity. Thus, similar to what can be done with pressure-based interaction, different shaking intensities could be used to replace different activities (like e.g., tap and double-tap). However, this interaction method is not usable for people with uncontrollable movement like e.g., spastic patients.