An example to show the collision avoidance difficulty. In this case, the subject vehicle (red) is following a leading vehicle (white, 50 m ahead, vn = 8.33 m/s) with a higher velocity (vs = 16.67 m/s). Equation (18) and (19) define the safe velocity set V as the blue area, e.g., if the current subject velocity is any one of the elements in V (e.g., v 1 and v 2 ), the neighbouring vehicle (white) is not looming. Namely, the collision avoidance difficulty is zero. In this example, since the subject vehicle is driving faster than the leading vehicle, the current subject velocity vs / ∈ V , indicating that the neighbouring is looming regarding the subject vehicle. The distance from the subject velocity vs to the safe velocity set V (the safety boundary) is vg (the red arrow), the length of which is the defined collision avoidance difficulty.

Context in source publication

Context 1

... equal sign stands when v s is at the boundary of velocity set V . We define the collision avoidance difficulty ||v g || as the 2D distance from the current subject velocity v s to the boundary of the safe velocity set V (Equation (21)) (See Figure 5 for illustration). If the current subject velocity v s is within the set V , the velocity gap is zero, which means the collision avoidance difficulty is zero. ...