基于功能分配的汽车悬架/转向系统可拓控制及稳定性分析

Function Allocation Based Vehicle Suspension/Steering System Extension Control and Stability Analysis

考虑汽车悬架与转向系统耦合动力学关系,建立整车集成系统动力学模型。选取偏差与偏差微分作为特征量,建立关于特征量的可拓集合。根据关联函数,划分经典域、可拓域、非域三种测度模式。在不同可拓集合范围内对控制功能进行分配,分别设计对应功能控制算法,构建基于功能分配的可拓控制器,以尽可能改善集成系统控制性能。对由最优控制和基于功能分配的可拓控制器构成的闭环控制系统,进行仿真和试验研究,结果表明基于功能分配的可拓控制可进一步全面提高悬架和转向集成系统的控制性能,可拓控制具有获得更佳地控制效果的能力。在不同控制方法下,以悬架、转向系统参数作为变量,对集成控制系统的稳定性进行分析。结果表明,采用可拓控制,控制系统稳定性更佳;增大悬架阻尼、车速、前轮转向角至一定值时,汽车时域响应不稳定程度增加;改变可拓控制器偏差控制系数,对集成控制系统性能均有不同程度的影响;不断增加可拓控制器功能控制系数,系统各项控制性能会发生突变而失去稳定性。

Considering coupled dynamics between vehicle suspension and steering systems, the dynamic model for full-vehicle integrated system is built. The deviation and deviation derivative are chosen as the characteristic quantities, and the extension set is established. The three measure modes of the classical domain, extension domain and non-domain are divided according to the correlation function. The control functions are allocated in different extension sets, and the corresponding control algorithms are separately designed to form the function allocation based extension controller（FAEC）, in order to improve integrated system control performance as far as possible. The closed-loop control systems are constituted by the optimal controller and FAEC, and the simulation and test is carried out. The results demonstrate that the FAEC can further improve the control performance of the integrated system, which has the ability of obtaining better control effects than the optimal control. The integrated control system stability is analyzed when utilizing the suspension and steering system parameters as the variables by different control methods. The analysis results show that adopting the FAEC, the control system is with better stability. When increasing suspension damping, vehicle velocity and the front-wheel steering angle to certain values, vehicle time-domain responses＇ instability degree increases. And when changing the FAEC error weighted coefficients, it brings different degrees of influences to the integrated control system performance. If increasing the extension controller function control coefficient constantly, it leads the vehicle control system to instability.