Robert Broström

A comparison of two contemporary types of in-car multifunctional interfaces.

A driving simulator study was conducted to investigate the effects of carrying out a variety of tasks using two different types of contemporary in-car multifunctional interfaces: a touch screen interface and an interface manoeuvred by a rotary control. Participants drove on a curved rural road while performing tasks such as list scrolling, radio tuning, alphanumeric input and continuous adjustments. The results indicate that, in terms of task completion time and the number of glances made to the display, the optimal interface is dependent on the task being performed. The touch screen interface was better for alphanumeric input tasks and the interface manoeuvred by a rotary control was better for continuous adjustments and list scrolling. Alphanumeric input seems to be more demanding than other tasks, independent of the interface used. It was apparent in this simulator study that both interfaces affected the lateral control performance, but lateral control performance deteriorated to a greater extent when the touch screen interface was used, probably partially as a result of the lower display position.

Correlation between safety assessments in the driver-car interaction design process

With the functional revolution in modern cars, evaluation methods to be used in all phases of driver-car interaction design have gained importance. It is crucial for car manufacturers to discover and solve safety issues early in the interaction design process. A current problem is thus to find a correlation between the formative methods that are used during development and the summative methods that are used when the product has reached the customer. This paper investigates the correlation between efficiency metrics from summative and formative evaluations, where the results of two studies on sound and navigation system tasks are compared. The first, an analysis of the J.D. Power and Associates APEAL survey, consists of answers given by about two thousand customers. The second, an expert evaluation study, was done by six evaluators who assessed the layouts by task completion time, TLX and Nielsen heuristics. The results show a high degree of correlation between the studies in terms of task efficiency, i.e. between customer ratings and task completion time, and customer ratings and TLX. However, no correlation was observed between Nielsen heuristics and customer ratings, task completion time or TLX. The results of the studies introduce a possibility to develop a usability evaluation framework that includes both formative and summative approaches, as the results show a high degree of consistency between the different methodologies. Hence, combining a quantitative approach with the expert evaluation method, such as task completion time, should be more useful for driver-car interaction design.

Can Haptics Facilitate Interaction with an In-Vehicle Multifunctional Interface?

A driving simulator study was conducted to investigate whether interaction with an in-vehicle multifunctional interface maneuvered by a rotary control can be improved if assisting haptics is provided. Two conditions were compared in the study, one in which neutral haptics was provided through the rotary control and another in which enhanced haptics was provided. Participants drove on a curved rural road while performing tasks such as list scrolling, radio tuning, address and number entry, and sound settings adjustments. When enhanced haptics was provided, the radio tuning was faster and fewer glances to the display were required, and the sound settings adjustments were completed with a reduced duration of the glances. However, improvements are needed for the other tasks. Enhanced haptics seems to facilitate interaction with functions in which the sensations can be incorporated in an intuitive way.

Drivers Quickly Trust Autonomous Cars

Successful introduction of autonomous cars require autonomous technology that users experience as trustful and useful. The aim of the study reported in this paper was to explore if drivers trust a fully autonomous car and if they experience that in-vehicle tasks can be conveniently carried out when in full autonomous mode. The test was conducted on a test track and an autonomous research car was used. The car was capable of handling the test track driving environment with full autonomy. When in full autonomous mode the participants got to engage in individually selected tasks, such as use media display, read, eat, drink and carry out work tasks with their own portable devices. The results show that participant trust the autonomous car and they find it convenient to conduct in-vehicle tasks while in full autonomous mode.

Assessing In-Vehicle Secondary Tasks with the NHTSA Visual-Manual Guidelines Occlusion Method

The NHTSA Visual-Manual Distraction Guidelines propose two methods for evaluating which in-vehicle tasks should be allowed while driving. Of these, previous studies have shown that the Eye Glance measurement using Driving Simulator method (EGDS) has low reliability. This study therefore explored if the other proposed method, Occlusion Testing, provides a better alternative. Occlusion testing did indeed show more robust performance than EGDS. It also was more permissive, i.e., tasks that failed with EGDS passed with Occlusion. Furthermore, results indicate that for many tasks, Occlusion testing can be replaced with a simpler step count method. Two drawbacks were also identified. First, tasks requiring longer system search times are systematically allowed fewer interaction steps for completion. Second, test outcomes are highly dependent on participant instructions. Participants who perceive the evaluation as an individual test use more effort and develop optimization strategies, which means complex tasks that normally would fail will pass.