Abstract
TNO Human Factors and TNO Automotive are investigating relationships between subjective and objective measures in the area of vehicle handling. This paper presents a driving simulator study and a field experiment in which these relationships were investigated. First, in the driving simulator experiment, the characteristics of the steering system of the simulated vehicle were manipulated. With various steering systems, subjects drove on a 2 km normal straight lane, as well as through short and narrow tracks marked with cones. Questionnaires were used to obtain subjective ratings and workload measures. Results of the driving simulator experiment led to the test method that was used for the field experiment.
In the second phase, actual vehicle tests were performed. The scope of these field experiments was to test the hypothesis that the subjective assessment correlates with driver workload. Using a single vehicle in this type of research is essential: Only then will the assessment not be biased by factors that are not under test such as (amongst others) seating comfort and driveline behaviour. Therefore, a single vehicle was used ,which has been equipped with a steer-by-wire system to enable on-line modification of steering parameters. This allows testing a large number of steering settings or even control principles in a short stretch of time. Three steering parameters were varied in the test car. Twelve experienced drivers assessed the on-centre handling behaviour of various settings on two test tracks; a straight road section and a short manoeuvre marked with cones.
The results of both experiments are discussed as well as the usability of the methodology for the development and HMI-assessment of new steering concepts.