Page - 76 - in Integration of Advanced Driver Assistance Systems on Full-Vehicle Level - Parametrization of an Adaptive Cruise Control System Based on Test Drives

6. Upper Level Controller Parameter Identification x0 y0 STO P Ego 1P yv ys xs,xv FOV OTF Figure 6.5.: Example of an incorrectly identified standstill situation 6.2.1. Standstill Situation As already mentioned, the conditions for the standstill situation are that the ego vehicle and the OTF velocities equal zero, vvx = 0, and svOTF = 0. There may be situations when all these conditions are satisfied, but the ego vehicle is not actually following the OTF.Figure6.5 showssuchanexample. Here, theegovehicle is followingtheOTF.The ego vehicle stops at a cross-walk because a pedestrian P1 crosses the road, and the OTF stops at a stop sign at a bigger inter-vehicle distance. With the conditions mentioned above, this situation is defined as a standstill situation, which is not true. Therefore, another condition has to be introduced, which is described by Kreyszig in [Kre99]. He defined that the samplex is an outlier if one of the conditions x<IQR−1.5ql or x>IQR+1.5qu (6.10) is satisfied, whereby ql is the lower quartile, qu is the upper quartile, and IQR is the interquartile range reading IQR= qu−ql for the data set of x. Figure 6.6 shows the histogram for the unfiltered s0 and the filtered s0 according to eq. (6.10). There, it can be seen that inter-vehicle distances up to 35m may occur. Situations with such large distances are similar to fig. 6.5. The filtering reduces the number of standstill situations from 533 to 441. For further investigations, the filtered data set for s0 is used with its mean value of s¯0 = 1.978m, which correlates very well with the values mentioned in literature. In [MY08], Moon et al. identified a clearance at zero speed of 1.98m. Both values nearly meet the requirements out of standard [Tec09], which stipulates that the inter-vehicle distance should not fall below 2m. 6.2.2. Constant Following Scenario For the constant following scenario, the ego vehicle velocity must fulfil vvx≥ 1.5m/s, and the inverse of the Time to Collision (TTC) must be less than a certain limit of 76