Automobile manufacturers manage a big effort to ensure driving safety of their cars by testing them in all relevant driving manoeuvres and on different surfaces. Extensive measurement equipment is used to describe the driving behaviour in those tests by objective characteristic values. In straight-line braking and braking while cornering, the measurable yaw rate deviation is a well known and proven characteristic value to describe the driving safety of a car in these tests. The goal of this study was to analyze the objective and measurable lane keeping ability of normal drivers in straight-line braking and braking while cornering with respect to selectively varied yaw rate deviations. In a representative experiment, including 100 normal drivers, the yaw rate deviation of a fully instrumented vehicle was varied by use of a rear wheel steering up to 16 °/s fixed control value. The driver's task was to follow a given lane, marked with cones, as exactly as possible after braking. Based on accurately captured path deviations by a Differential GPS-System, a progressive loss of lane keeping ability with increasing values of yaw rate deviation could be observed. As one result, the mean lateral displacement increases progressively with increasing yaw rate deviation, whereas the mean controllability-disturbance rating of the drivers increases linear. This correlation was confirmed at straight-line braking from 80 / 120 km/h and braking in a turn from 80 km/h. Furthermore, maximum values of yaw rate deviation, lateral acceleration or side slip angle in open-loop tests were rather suitable to explain the observed values of subjective rating and steering effort than fixed time values. Especially the maximum yaw rate deviation within one second after brake initial in open-loop tests confirmed to be a proper value to explain the driving safety characteristics in closed-loop tests. In detailed analysis of dependencies, no significant differences in subjective controllability rating between straight-line braking and braking in a turn were detected, while the mean maximum path deviation depended on the braking manoeuvre. In braking while cornering, the presumption of increased path deviation without any yaw rate deviation was confirmed and an increased need for lane width was verified only above 10 °/s yaw rate deviation. Summarized, the maximum path deviation seems to be a proper value to describe the lane keeping ability of non-professional drivers. In particular, the clearly increasing value of mean lateral displacement indicates the expected loss of lane keeping ability by normal drivers due to high values of yaw rate deviation. According to the introduction, task fulfilment - staying inside the driving lane - is a necessary condition for driving safety. In this study, task fulfilment in 96 % of all cases resulted in noncritical subjective ratings and even no driver rated the vehicle's driving behaviour as critical, when all drivers were able to stay inside the lane. In contrast, lane violations, despite noticeable cone accidents, did not obligatory result in critical subjective ratings (only in 53 % of all cases). Hence, to prevent a potential loss of lane keeping ability of customers by determining a safe open-loop driving behaviour, these observed relations between noncritical subjective ratings and lane violations point out, that it seems more appropriate to assess path deviations and lane violations in closed-loop tests than a sole use of subjective rating.


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    Titel :

    Lane keeping ability of normal drivers depending on selectively varied yaw rate deviation in braking manoeuvres


    Beteiligte:


    Erscheinungsdatum :

    2011


    Format / Umfang :

    11 Seiten, 6 Bilder, 2 Tabellen, 23 Quellen


    Anmerkungen:

    (nicht paginiert)



    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Datenträger


    Sprache :

    Englisch





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