Investigating design issues for the use of touchpad technology within vehicles

This paper provides an overview of two studies investigating the human factors design issues for touchpad technology within vehicles. A prototype touchpad system was utilised in which drivers were able to enter characters (e.g. ‘C’ for climate) and gestures (e.g. a right to left line to represent backspace) to interact with climate, audio, navigation and vehicle settings functions. In study 1, an emphasis was placed on the research question: where should a touchpad be located within a vehicle? Sixteen participants (50:50 right/left handed) drove three routes along a motorway in a right-hand drive simulator while following a lead vehicle at a perceived safe distance. At specific points participants were asked to carry out three tasks of varying complexity using the touchpad (e.g. enter a phone number). For each route, the touchpad was positioned in one of three locations in the vehicle: in the centre console (to left of driver); in the door armrest (to right of driver); and in the steering wheel. Results showed clear differences in the performance and preferences of right-handed people versus lefthanded people. Right-handed people preferred the door armrest location and made few glances towards this location while driving. In contrast, left-handed drivers were more positive towards the centre console location. The results for the steering wheel location were mixed. Whilst task times were relatively low for this location, drivers often made a considerable number of glances towards the touchpad within the steering wheel. Study 2 focussed on the question: which tasks are most appropriate for the use of touchpad technology? Eighteen participants drove three routes in the right-hand drive simulator whilst following a lead vehicle. At particular points drivers were requested to carry out tasks of varying complexities and qualities. For each of the routes, drivers carried out the tasks whilst using either: the prototype touchpad system; a touchscreen; or a rotary controller interface. Results indicated that participants were most negative (in terms of preferences) and performed least well (in terms of task time, visual demand and driving performance) with the rotary controller. The results for the touchpad versus the touchscreen interfaces were task dependent. For instance, with the touchpad, subjective opinions and performance were most positive for tasks in which simple commands enabled drivers to bypass the need for complex menu interactions (e.g. changing the interior temperature). In contrast, results for the touchscreen were evidently superior for simple menu selection tasks (e.g. selecting a preset radio station).