Considering the kinematics of the vehicle moving in the horizontal plane with fixed coordinates [9] on it as shown in Figure 1, the acceleration of the vehicle can be obtained from Equation 1. When γ is a yaw angular velocity of vehicle or yaw rate. From Figure 1, the angle between the vehicle traveling direction (t-direction) and longitudinal direction (x-direction), β, is determined by tan^(-1)(v/u). This angle is called side slip angle of the vehicle center of gravity (β). When side slip angle is small the magnitude of longitudinal velocity (u) is almost same as vehicle velocity (V). While magnitude of lateral velocity (v) can be obtained from multiplication between vehicle velocity (V) and side slip angle (β) as shown in Eq. 2. By taking the derivative to equation 2 and substituting into Equation 1, acceleration of vehicle (R ̈) can be written as equation 3