IEDC-2010 Conference Proceedings (Download ... - NED University

PSD((m/s 2 ) 2 /Hz)
behavior of the sampling interval. The sampling intervals were set to the 3 patterns: 0.25m x 0.10m,
0.50m x 0.20m, and 1.00m x 0.40m, the vehicle parameters were those for the medium vehicle shown in
Table 1, and the traveling speed was 40km/h. Figure 3 shows an example of a comparison of the PSD
results for vertical acceleration.
10 -3
10 -4
10 -2 0.25m×0.10m
0.50m×0.20m
1.00m×0.40m
10 -5
10 -6
10 -7
10 -8
10 -9
10 -10
10 -11
0.01 0.1 1 10
Frequency(Hz)
Figure 3. Comparison of vertical accelerations for different sampling intervals
From the results in Figure 3, it can be seen that although in the frequency band lower than 2Hz, the PSD
for the 3 sampling intervals show virtually the same trends, in the frequency band higher than 2Hz there
are differences in the PSD trends due to changes in the sampling interval. Also, from the comparison of
the PSDs for the lateral acceleration due to differences in sampling interval, similar trends to those of the
vertical acceleration were found.
Based on these results, it was decided to use the two-dimensional profile data with the minimum sampling
interval of 0.25m x 0.10m that is capable of being acquired by the road surface measurement vehicle used
in this research for subsequent comparison investigations. However, it is considered that if in the future it
becomes possible to acquire two-dimensional profile data at sampling intervals finer than 0.25m x 0.10m,
it will be necessary to again investigate the effect on vehicle behavior of the difference in sampling
interval.
3.3 Effect of differences in vehicle type on the vehicle behavior
The vehicle parameters were varied and vehicle behavior simulation was carried out with the objective of
confirming the effect of differences in vehicle type on the vehicle behavior. The vehicle parameters were
the 3 patterns shown in Table 1, namely the large vehicle, the medium vehicle, and the small vehicle, and
the traveling speed was 40km/h. Figure 4 shows a comparison of the PSDs for the vertical acceleration
and the lateral acceleration.
From the results in Figure 4, it can be seen that although for both the vertical acceleration and the lateral
acceleration, the overall trends of increasing and decreasing in the PSDs were similar for each vehicle
type, there was a certain amount of variation. In particular, in the case of the vertical acceleration, in the
frequency band 3Hz to 5Hz, the large vehicle displays a different trend from those of the medium and
small vehicles.
From these results, it was found that if the vehicle type is changed, there are differences in vehicle
behavior. The reasons for this are the wheelbase and the threads are different in each vehicle type, so the
trajectory traveled on the road surface is different, and because vehicle characteristics such as vehicle
Proceedings of IEDC 2010, 1-3 July, 2010
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IEDC-143-022