Independent Design of Yaw Rate Gain and Phase Characteristics in SBW Vehicle

This article proposes a method to independently control the gain and the phase characteristics of the vehicle frequency response. In steer-by-wire vehicle, it is possible to design the characteristics of vehicle dynamics like the yaw response. However, the gain and phase of the frequency response of linear systems are coupled which limits the tunability. Therefore, when one characteristic is changed, the other is changed too. To deal with this issue, we propose a control method for enabling independent gain and phase characteristics of the yaw rate dynamics on a steer-by-wire system. The construction of a NARX model with a neural network enables generating the nonlinear characteristics. Furthermore, a LQR controller calculates the front wheel angle to track the nonlinear target yaw rate. The proposed control is validated on a steer-by-wire equipped vehicle. The control strategy is described and experimental data demonstrate the improvement on maneuverability and stability.