Users with severe motor or cognitive impairments often lack the degree of fine motor control required to use input devices, such as
mice, joysticks or controllers, typically used to control an avatar in a 3D environment. Consequently they have to revert to using input devices, such as an eye tracker or single switch controller that have been specifically designed to accommodate their abilities. Assistive devices are constrained in the amount and types of input that can be provided, for example a single switch may only be able to provide a binary (on/off) input. A larger amount of input (at a slower rate) can be provided through switch access scanning, where users iteratively make a discrete selection from a predefined set of input options. Though existing scanning systems are efficient for linear types of input such as text entry or accessing menus, we found these to be non-optimal for providing non-linear type of inputs. Navigating a 3D avatar is an example of non-linear input as players may hold a particular key for an indeterminate amount of time, as well as hold two keys at the same time to adjust the course of their avatar. Providing these types of input using existing discrete scanning methods is inefficient and erroneous, as they have to be approximated with individual discrete key presses. We developed a new scanning mechanism called hold-and-release that allows switch users to efficiently navigate an avatar in a 3d environment.
How it works
Through the analysis of navigation behavior of Second Life users, a new scanning system was developed based on the frequency of inputs used (FORWARD, BACK, LEFT, RIGHT). Rather than making a discrete selection when the switch is activated, we hold the input until the user releases it using another switch activation. After activating an input the scanner will keep iterating over the remaining inputs so combined inputs can be generated (FORWARD+LEFT).
A number of different variations of our scanning technique were evaluated using simulation, demonstrating that hold-and-release is significantly faster than using discrete scanning techniques.
A switch controller.
Eelke Folmer, Fangzhou Liu, Barrie Ellis. Navigating a 3D Avatar using a Single Switch, In Proceedings of Foundations of Digital Interactive Games (FDG'11). Pages 154-160, Bordeaux France, June 2011. [29% acceptance rate]