考虑主动时滞的汽车悬架系统控制特性研究

Research on control characteristics of vehicle suspension system with intentional time delay

以汽车悬架系统为研究对象,采用理论和试验相结合的方法对考虑主动时滞的悬架系统控制特性进行分析。首先建立含时滞悬架系统动力学模型,分析系统的控制稳定性。理论和仿真结果均表明,采用传统二次型最优控制律不能保证含时滞系统的稳定性。系统时滞量存在稳定区间,时滞超出稳定区间时系统将失稳发散;为了保证控制系统的稳定性,采用状态变换法设计了含时滞系统的主动控制律,计算表明,该控制律可以保证系统稳定性。研究还发现,时滞量的变化会使系统振动幅值产生较大改变,为此在控制系统中引入主动时滞,研究主动时滞对系统振动特性的影响,计算表明,合理的主动时滞可以降低系统振动幅值;为验证结果的正确性,搭建了悬架时滞主动控制试验平台,通过对相同工况下仿真结果与试验结果进行对比,发现两者具有较好的一致性;而由于悬架受到的路面激励具有随机性,采用含时滞系统的主动控制律对路面随机激励下的悬架系统进行控制分析,发现当主动时滞为0.04 s时,车身加速度均方根值比无主动时滞降低了39.4%,说明主动时滞对悬架控制的有效性。本文研究对时滞主动控制的理论研究具有重要的促进作用。

A vehicle suspension system with time delay is taken as the research object.The active control characteristics of the system with intentional time delay are studied by combining theory with experiment.Firstly,the dynamics equation is established,and the stability characteristics of the system are analyzed.The theoretical and simulation results show that under the classical second order optimal control law,the system is stable when the time lag is in the stable interval;otherwise the system becomes unstable with divergence.Therefore,the time-delayed active control law is designed based on state transformation.The simulation results show that the law can guarantee the stability of the system.It is also found that the change of the time lag will make the vibration amplitude of the system greatly change.Therefore,the intentional time delay is introduced in the control system,and the influence of the intentional time delay on the vibration characteristics of the system is studied.The calculation shows that the reasonable active time delay can reduce the vibration amplitude of the system.In order to verify the correctness of the results,a time delay active control suspension experimental system is set up.And it is verified through the simulation results compared with the experimental results under the same working conditions.The results show that adding reasonable intentional time delay in control can produce a better damping effect.Experimental results and simulation results have good agreement.Therefore,the research shows that it has high credibility.Due to the randomness of road excitation,finally,the suspension time-delayed optimal active control are analyzed under random excitation,the results show that when the active delay time is 0.04 s,the acceleration of the sprung mass RMS value is 39.4%lower than that without active time delay.It indicates that time-delayed active control has important engineering application value and plays a significant role in promoting the theoretical research of vehicle active suspension system with time delay.