Page - 68 - in Integration of Advanced Driver Assistance Systems on Full-Vehicle Level - Parametrization of an Adaptive Cruise Control System Based on Test Drives

5. Selection of the Object to Follow x0 y0 0b fl,ju fr,ju rr,ju rl,ju path predicted ,5js boundary left path boundary right path (a) [m]s 0 20 40 60 80 100 0 1 2 3 (b) Figure 5.6.: (a) Special case of eq. (5.39) and (b) non-constant path width b as function of s, as described in eq. (5.41) 5.3.2. Priority Algorithm The Priority Algorithm is another possible way to select the OTF. As described in eq. (5.37), every object is represented as a list of four points. In the special case where eq. (5.39) is fulfilled, a fifth point is added to the list, as described in eq. (5.40). Each of these points has a corresponding priorityP, which is calculated using the equation P (s,u) = ( b1s 2 +b2s+b3 ) e−c(s)u n , (5.43) where the coefficients b1 to b3 and c(s) are determined using the boundary conditions P (0,0) =P0, P (L,0) =PL, ∂P ∂s ∣∣∣∣ s=0 u=0 = 0 and (5.44) P ( s,±b(s) 2 ) =Pb. This results in a polynomial of second order in the longitudinal directionsof the natural coordinate system. In the lateral direction u, the function is described by a Gaussian Bell Curve if the parameter n= 2. If n is increased (e.g. n= 4,6,· ··), the shape of the function becomes increasingly rectangular. The parameter c(s) is a function of the longitudinal coordinate, if the path width is a function of s. If the path width is set to a constant value of b0, then c is constant for all s. Figure 5.7 showsP (s,u) of eq. (5.43) for the two cases n= 2 and n= 8. For the path width, the function and parameters given in chapter 5.3.1.2 are used. 68