摘要：
To relieve the adverse impact of time delay on working effect of the magneto-rheological semi-active suspension system,a LQG-Pade approximation rhythmic (LQGPAR) control is presented which does not implement control prediction to compensate time delay.Firstly,a time delayed magneto-rheological semi-active suspension based on a 2-degree-of-freedom quarter-car model is built,for which a LQG controller is designed to obtain the ideal active force signal.Secondly,Pade approximation is added on the ideal active control force signal to obtain the delayed active control force signal which is used to calculate the control current of the magneto-rheological absorber with the suspension motion velocity.This arrangement is implemented to eliminate mismatching between the suspension motion velocity and the actual semi-active control force.Finally,compared with LQG controller without time delay control measures,ideal LQG controller (without time delay),Smith PredictorLQG (SPLQG) controller and the passive suspension,comparisons and analyses on suspension performance are conducted.Results show that time delay has a great effect on the high-frequency vibrations of suspension systems,and especially dynamic load of vehicle wheel is influenced most obviously because its vibration encrgy focuses on the high frequency band.With time delay increase,the suppression effect of high-frequency vibration deteriorates,specially for the LQG controller without time delay control measures.Compared with the passive suspension,the SPLQG controller can respectively improve suspension comprehensive performance by 18.69％ and 8.75％,and the proposed LQGPAR controller can respectively improve suspension comprehensive performance by 32.24％ and 29.28％,when time delay equals 25ms and 30ms respectively.%为降低时滞对磁流变半主动悬架工作效果的负面影响,提出一种有别于常规控制量预测时滞补偿的LQG-Pade逼近合拍(LQG-Pade approximation rhythmic,LQGPAR)时滞控制方法.首先,建立考虑时滞的1/4车2自由度的磁流变半主动悬架模型,并基于此模型设计LQG控制器求得理想主动力信号.其次,通过对理想主动力信号进行Pade逼近操作获取考虑时滞的滞后主动力信号,并根据该信号和悬架相对运动速度求取磁流变减振器的控制电流,进而使磁流变减振器的实际响应和悬架相对运动速度合拍.最后,以无时滞控制措施的LQG(无措施LQG)控制器、理想LQG控制器(无时滞)、史密斯预估-LQG(Smith Predictor-LQG,SPLQG)时滞补偿控制器及被动悬架为比较对象,进行悬架性能对比与分析.结果显示:时滞对悬架系统高频振动影响比较明显,尤其是对振动能量集中在高频段内的车轮动载荷的影响最为明显,时滞越大,悬架系统高频振动的抑制效果越差,其中无措施LQG控制器所受影响最为明显;与被动悬架相比,时滞分别为25ms和30ms时,SPLQG控制器能使悬架综合性能分别改善18.69％和8.75％,而LQGPAR控制器可使悬架综合性能分别改善32.24％及29.28％.
