双离合器自动变速器换挡过程的内模控制

为提高双离合变速器的换挡过程平顺性,提出内模控制方法,提高离合器转速差的跟踪精度。设计转矩干扰补偿器来减小发动机端与负载端转矩扰动的影响,并基于平滑可微的参考转速差设计超前校正控制器。即使存在模型不确定与干扰,内模控制系统能维持稳定。仿真与台架实验结果表明,在不同参考输入与模型参数情况下,所提出的控制器均能达到较小的跟踪误差和平顺的换挡效果。     

Stability Analysis of a Force-Aided Lever Actuation System for Dry Clutches with Negative Stiffness Element

A force-aided lever with a preload spring is not only force-saving but also energy-saving. Therefore, it has great potential to be applied to dry clutch actuations. However, the negative stiffness of the clutch diaphragm spring introduces unstable dynamics which becomes more intensive due to the preload spring. In order to explore the intensified unstability, this paper builds dynamic models for the rotating lever coupling a negative stiffness diaphragm spring and a preload spring. The stability analysis using the Routh-Huiwitz criterion shows that the open-loop system can never be stable due to the negative stiffness. Even if the diaphragm spring stiffness is positive, the system is still unstable when the preload of the spring exceeds an upper limit. A proportionalintegral- derivative (PID) closed-loop scheme addressing this problem is designed to stabilize the system. The stability analysis for the closed-loop system shows that stable region emerges in spite of the negative stiffness; the more the negative stiffness is, the less the allowed preload is. Further, the influences of the dimensions and PID parameters on the stability condition are investigated. Finally, the transient dynamic responses of the system subjected to disturbance are compared between the unstable open-loop and stabilized closed-loop systems.