On-centre handling : a driving simulator experiment. Carried out within the project “Automotive Comfort and Handling Identification and Estimation through Virtual Evaluation” (ACHIEVE), partially sponsored by the TNO Board of Directors.

TNO Human Factors and TNO Automotive are investigating relationships between subjective and objective measures in the areas of vehicle handling. This report presents the general approach to be followed in the project, and a driving simulator study that was carried out to refine the methodology. The project is sponsored by the TNO institutes involved and by the TNO Board for Directors. In the driving simulator experiment, the characteristics of the steering system of the simulator 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. In addition to the normal driving condition, occlusion and the Peripheral Detection Task were applied as candidate dependent measures. Questionnaires were used to obtain subjective ratings and workload measures. Most of the measures based on the steering wheel signal yielded effects of the steering system parameters variations. The only exception is the proportion of high-frequent steering (High-Frequency Area, or HFA): since the shape of the frequency spectrum was not altered, the HFA remained unchanged. Dependent on the gap size used, the Steering Reversal Rate can yield an effect in one direction, no effects at all, or an effect in the other direction. Most dependent variables that incorporate vehicle motion (standard deviations of lateral position, lateral speed, and lateral acceleration) yielded no significant effects. The Time-to-Line Crossing measure was more sensitive: this measure did produce significant effects of the steering system variations. In the questionnaires, only a few effects of system settings were found. Conclusions: To find differences among steering system conditions, straight lane driving on a normal lane is more suitable than driving through short, narrow tracks marked with cones. From the latter group, a curve with constant radius is to be preferred with respect to a straight lane with narrower and offset sections. In terms of workload, measures based on the driver’s steering activity distinguished among conditions, whereas questionnaires, occlusion and the Peripheral Detection Task did not. The questionnaires used to obtain driver judgements about the steering characteristics have to be refined. (Author/publisher)