where \( \alpha_{bv}\) is the estimated aggressiveness of the obstacle vehicle. \(\sigma\) defines the shape of the aggressiveness field. The velocity in the numerator is to eliminate the variated distance created by the subject vehicle itself. In order to accurately measure the parameters, we first assume \(A_f(\Delta v, \Delta\varphi)\), \(\sigma_{X}(v_{sv})\), \(\sigma_{Y}(\Delta\varphi_{sv})\) are linear as below.