2022 JSAE Award The Outstanding Technical Paper Award1. IntroductionTechnical Awardsvariations can be reduced by adding a certain amount of pitch motion to the steering angle in order to reduce variations. This hypothesis was verifi ed using a driving simulator, and the quantitative effect of the variation reduction was extracted. Following our previous work, which clarifi ed the vehicle characteristics that enable drivers to drive accurately, on average, along a target driving line, this research focused on the vehicle characteristics that enable accurate driving with little variations between trials.To explain this research, an outline of our previous work and the variation in the line trace deviations, which is the subject of the present study, is fi rst provided. Next, the driver steering mechanism, which is considered to cause variations in the minute steering angle range and also defi ned as a hypothesis in the previous work, will be described; the reasons for choosing the pitch as the vehicle behavior to be added to reduce variations are also explained. Subsequently, the quantitative pitch characteristics that can reduce the variation in the line trace deviations based on the driver sensitivity characteristics (related to the pitch motion obtained from experiments) are hypothesized, and the results of the experimental verifi cation are reported.In this study, two experiments were conducted with 25 male drivers in their 20s and 50s who drove their cars on a daily basis. The tests were examined and approved by the Experimentation Ethics Committee of Nissan Motor Co., Ltd., and informed consent was obtained from the test participants.In our previous study, an evaluation course was established, consisting of an R1200 curve and its 2. Outline of and issues in our previous study*Nissan Research Center Mobility & AI Laboratory **Powertrain and EV Performance Engineering Department ***Customer Performance and Test Engineering Methodology Innovation Department ****Vehicle Performance Engineering DepartmentAbstract When driving along a straight roadway, a driver regularly makes minute steering adjustments in order to maintain the vehicleʼs position within the driving lane. In the research of the previous report, the quantitative relationship of several steering characteristics in this scenario was clarifi ed for accurate line tracing. However, it was found that the deviation of the tracing line by trials was not small at the same time. This paper clarifi es one of the factors of the deviation and its improvement by adding minute pitching motion to the vehicle in proportion to the steering angle. For the daily driving scenarios encountered by typical drivers, most driving is performed along straight trajectories, including operations performed for fi ne adjustments in the travel path with small steering angles. According to our survey conducted in Europe and Japan, steering with angles of 5° or less, which is considered as minute steering, accounts for more than half (51.1%) of all steering across all vehicle speed ranges and approximately 80% (79.6%) in zones with higher speed limits of 80 km/h or more, which is supported by some data. The traceability of a target driving line with such small steering angles is an important aspect of performance that is frequently encountered by many drivers; however, its mechanism has not been fully clarifi ed thus far. Therefore, at actual development sites, there are many cases where the development of this ability relies on tuning an actual vehicle.With regard to this issue, our previous paper 1) clarifi ed the quantitative relationships between the steering force and yaw characteristics with respect to line traceability; this was achieved by quantitatively determining the dead zone of the driver in the minute steering angle range and the dead band of the yaw characteristics of the vehicle and then analyzing the relationship between the evaluated line traceability defi ned in the study and the two dead zones. However, a new issue was also observed: the line trace deviations of the drivers varied considerably between trials.In this study, considering that one of the causes of this variation in the line tracing deviations originates from the steering mechanism of the driver within the minute steering angle range, it was hypothesized that the NISSAN TECHNICAL REVIEW No.88 (2022)88101A Study on Pitch Characteristic to Reduce Line Trace Mitsunori Tao* Naoya Machida** Yutaka Hayashi*** Ken Nagasao****Deviation in Small Steering Angle
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