基于LMI方法的车辆侧倾运动安全主动悬架H2控制器设计

为提高车辆转向-侧倾运动工况的安全性,基于线性矩阵不等式(LMI)方法设计侧倾运动安全主动悬架H2控制器,直接控制横向载荷转移率(LTR)。首先,建立车辆转向-侧倾运动动力学模型,选择LTR、侧倾角和侧倾角加速度构造车辆侧倾运动安全综合性能评价指标。其次,为避免现有LQG控制器设计方法无法处理综合性能指标中包含干扰项(前轮转向角)和控制加权矩阵为0导致控制向量无法求取的难题,基于LMI方法设计主动悬架H2控制器。然后,结合层次分析法和归一法,以鱼钩工况为典型转向工况仿真获取车辆转向-侧倾运动统计数据,进而确定了H2控制器的控制加权系数。最后,通过多工况数值仿真验证了侧倾运动安全主动悬架H2控制器的工作效果。结果显示:与被动悬架相比,在鱼钩工况、蛇形穿桩和双移线工况下,该H2控制器在不改变车辆转向运动状态的情况下使车辆侧倾运动安全综合性能评价指标分别降低39.05%、36.51%和42.31%,使LTR的均方根值分别降低15.87%、15.62%和14.86%。说明设计的主动悬架H2控制器具有良好的车辆侧倾运动安全控制效果。

LMI Method Based H_2 Controller Design of Active Suspensi on System for Vehicle Roll Motion Safety

To improve safety during vehicle steering-roll motion,a H2 controller of active suspension system based on linear matrix inequality(LMI)approach is developed to reduce lateral-load transfer ratio(LTR).Firstly,a dynamic model depicting vehicle steering-roll motion was established.LTR,roll angle and its acceleration were chosen to construct the comprehensive performance evaluating index of roll motion safety.Secondly,a design approach of H2 controller based on the LMI approach was proposed to overcome drawback that the common LQG approach not only cannot function when the determinant of the control weighting matrix is 0 matrix,but also cannot track the disturbance which is the front wheel steered angle in this research.Thirdly,control weightings of the H2 controller were determined by using analytic hierarchy process and normalization methods based on vehicle motion statistics under fish-hook maneuver as the typical steering condition.Finally,performance comparisons were implemented between the active suspension and the passive one under fish-hook,slalom and double-lane change maneuvers.Results showed that the newly developed H2 controller did not disturb vehicle steering motion,but decreased the comprehensive performance evaluating index of roll motion safety by 40.34%,36.59%and 42.31%,respectively.Specially,the root-mean-square of LTR,the most important evaluating index of roll motion safety,were decreased by 15.87%,15.62%and 14.86%,respectively.It is shown that the proposed H2 controller of active suspension system can achieve a good control effect on vehicle roll motion safety.