A long standing problem with heavy vehicle stability has been rollover. With the higher center of gravity, heavier loads, and narrower tracks (as compared to passenger vehicles), they have a lower rollover stability threshold. In this paper, a rollover stability control algorithm based on a two-degrees-of-freedom (DOF) and a three-DOF vehicle model for a two-axle truck was developed. First, the 3DOF model was used to predict the future Lateral load Transfer Rate (LTR). Using this LTR value, the dynamic rollover propensity was estimated. Then, a robust output feedback gain control rollover stability control algorithm based on the combination of active yaw control and active front steering control was developed. A H₂/H∞/poles placement multi-objective control strategy was developed based on the 2DOF reference model. After the control objectives were determined, the Linear Matrix Inequality (LMI) technique was utilized to solve the restrictions and to carry out the output feedback gain for the multi-input multi-output (MIMO) system. Finally, utilizing the commercial software TruckSim, the rollover stability control was evaluated using fishhook and step steering maneuvers. The simulation results show that the LMI robust controller could effectively improve the vehicle rollover stability.
