A Novel Coordinated Algorithm for Vehicle Stability Based on Optimal Guaranteed Cost Control Theory

Nowadays, with the great advancement of automobile intellectualization, vehicle integrated dynamic control is increasingly becoming a hot research field. For vehicle stability, this article focuses on the coordinated control of Direct Yaw-moment Control (DYC) and Active Front Steering (AFS). First of all, the nominal control variables (yaw rate and sideslip angle) are designed based on the linear two Degrees of Freedom (2 DOF) vehicle model, in which the phase difference between the actual and nominal variables has been pointed out due to the approximate substitution with first-order time-delay transfer function. Secondly, considering the uncertainty of cornering stiffness per axle, and increasing robustness of the system, the Optimal Guaranteed Cost Control (OGCC) theory is adopted to design the coordinated controller. To solve the problem of control delay caused by phase difference, a novel algorithm including a feedback part and a Feed Forward part is proposed properly, where the Feed Forward control is aimed to compensate for the delay problem. Besides, the approach of offline computation and online look-up is used to improve the real-time performance of the system. Finally, the Hardware-In-the-Loop (HIL) platform is built and the hierarchical control strategy is established. After the HIL tests on the condition of Sine with Dwell Waveform and Double-Lane Change, the results prove that the new algorithm proposed has better performance than that without Feed Forward part on vehicle stability control.