Abstract
As the number of personal computers installed in vehicles increases, a touchpad often used in a labtop computer can be used for the control of an in-vehicle information system (IVIS). Using a touchpad to control the system allows the user to select among large amount of information with a single touch of dragging. For safety and convenience of a driver, the touchpad could be placed on a steering wheel. This research is designed to calculate the most efficient Control-Response Ratio (C/R ratio) for the menu interaction of a touchpad on a steering wheel. Since the menu pointer's rate of movement and proper C/R ratio is determined by the amount of selected information, the amount of displayed information and the movement of a menu pointer was chosen to be independent variables. The dependent variables are a user's preference and task completion time. Two factor full factorial within subject design was used 16 subjects. The investigation revealed that the amount of selected information increased with increasing C/R ratio. The movement of the pointer became slower as the amount of information increased. The best C/R ratio was calculated for each amount of information and preference regression of the user's preference was drawn accordingly. Through this research, the automobile interior designer can benefit from the guidelines suggested for the touchpad control.
