【作者】 孙国春；

【导师】 田彦涛；

【作者基本信息】 吉林大学 ， 控制理论与控制工程， 2007， 博士

【摘要】 本文深入研究了动力总成主动隔振系统中涉及的作动器、主动悬置结构设计、控制系统建模和主动控制方法等关键技术。分别采用压电作动器和动线圈式电磁作动器设计了两种主动悬置结构,建立了它们的动力学模型,讨论了在不同控制方式下新型压电式主动悬置的隔振性能;设计了动力总成隔振试验台架,建立了系统十自由度动力学模型,并分析了在开环结构和采用线性二次型最优控制下系统的隔振性能。为降低实际车辆上控制系统的复杂性和减少控制成本,建立了动力总成隔振系统的五自由度简化模型;分别采用前馈控制和反馈控制两种方法对动力总成主动隔振系统进行了设计。由于与动力总成干扰信号相关性好的参考信号可以通过采集发动机转速来得到,前馈控制是一个较好的选择,采用滤波x-LMS自适应前馈控制方法收到了很好的控制效果。因为动力总成主动隔振可看作是干扰抑制问题,而H_∞最优控制的控制指标是使干扰对系统的输出影响最小,因而设计了基于H_∞控制器的输出反馈控制系统,控制器采用线性矩阵不等式的方法求解。为提高怠速工况和启动停车过程中的隔振效果,在性能加权函数的选取时,重点考虑了1～50Hz频率段的控制性能。仿真实验表明,基于H_∞控制器的输出反馈控制方法能较好地抑制动力总成干扰对车身的影响。为消除压电作动器的迟滞非线性特性,采取了基于逆补偿原理的自适应逆控制方法。在分析和比较各种迟滞模型的基础上,采用了Prandtl-Ishlinskii迟滞模型,推导出基于梯度法的在线参数估计自适应律。证明了采用Prandtl-Ishlinskii模型时,如果间隙模型算子采用对称结构,且各间隙模型的间隙和斜率都成比例时,迟滞非线性的补偿效果与斜率参数无关,斜率参数只会影响参考输入与实际输出之间的比例关系,因此在线估计参数可简化为一个。更多还原

【Abstract】 Automobile power-train is the dominant source of noise and vibration in automobiles, and the vibration isolation of automobile power-train is crucial to the improvement of NVH (Noise, Vibration and Harshness) characteristics.In order to reduce the power-train vibration’s impact on the passenger-comfort, the main methods have been disturbance attenuation, anti-resonance and vibration isolation. The vibration isolation system is the flexible connection device between the power-train and chassis. A sound system of vibration isolation can reduce the vibration of automobiles, vibration power from the power-train to the chassis and the noise induced. As a result, durability and passenger-comfort of automobiles are improved.At present, the power-train vibration isolation systems in most cars are rubber mounts and hydraulic damping mounts, which perform the function of vibration isolation and reducing noise to a great extent. Because of the problems of energy and environment protection, cars are being designed to be even lighter in weight. With the wide application of former driving motors, most cars use four-cylinder engines with poor performance in balancing, which make the problem of vibration in power-trains more obvious.Research indicates that the feature of ideal dynamical force in the mount system is that the system has a high static stiffness to hold weight of power-train and the output torque. When in low frequency, it should have a high stiffness with large damping to reduce large-amplitude vibrations caused by torque variations of engines when starting, braking, shifting and quick accelerating and decelerating. When in high frequency, it should have a low stiffness with small damping to reduce the transmitting of vibrations and improve the effect on reducing the noise. Ideal stiffness and damping of mount system should vary with the frequencies and amplitude of vibrations, which is hard to realize in real project. Although hydraulic damping mounts performed much better than the rubber mounts did in vibration isolation, there still exist some shortcomings, such as the stiffness not being big enough in low frequency and a phenomenon of hardening in high frequency.Active mounts system of power-train is an efficient way for vibration isolation of the automobile power-train. Active control technique should be applied to the vibration isolation system in the power-train with active mount system and proper control strategies. In this way vibration amplitude of chassis will be reduced greatly. This paper focuses on the key techniques of actuator selection, structure design of active mount, modeling of the control system and selection of control strategy. Content of the paper is as follows:Literatures about the research of active mount system are systematically reviwed, including both domestic and foreign development. Some foreign active and semi-active mount systems are mainly introduced. Different sensors and control algorithms for active control of vibration are summarized. Previous techniques in active control of vibration in automobile power-train are analyzed, and the problems in each situation are pointed out.According to the requirements for mount performance of the automobile power-train, two conditions which should be considered for design of active mount are proposed. Two active mount structures based on piezo-actuator and electromagnetic actuator are respectively designed. Dynamical models of the two active mounts are established. Performance of vibration-isolation with the piezo-actuator is discussed under different control schemes, which provides theoretical foundation for the design of active mount in power-train.Experimental platform of active mount in power-train is designed and the mathematical model with 10 DOF (degree of freedom) is established, which will facilitate the research. Performances of vibration isolation without control and with a linear quadratic regulator are analyzed by simulation experiments. The results indicated that performance of vibration isolation with active control scheme was better than passive control. A simplified mathematical model of active mount in power-train system with 5 DOF is built to reduce the cost of control and the complexity of actual control system in automobiles. Simulation results showed that the simplified model could capture dynamics of the complicated 10 DOF model well.Active vibration isolation system of power-train is designed by means of feedforward control and feedback control schemes respectively. As signals correlated with disturbance could be obtained by rotation speed of engines, feedforward control with adaptive x-LMS filter could eliminate vibration better than feedback control. In addition, the essence of active vibration in power-train is the problem of noise attenuation. The target of H∞optimal robust control is to minimize disturbance’s influence to system output. Considering the conclusions above, H∞output feedback control system is designed with LMI method. In order to improve the performance of vibration isolation in low-speed section, starting and stopping section, frequency between 1Hz and 50Hz is taken into consideration in the selection of weighting function. The results of experiment in simulation indicate that H∞output feedback control scheme can better restrain the influence caused by power-train to the body of the car.Adaptive inverse compensation is adopted to eliminate the hysteresis nonlinearity of piezo-actuator in active control system. The adaptive control law based on grads method is obtained with Prandtl-Ishlinskii model. It is proved that when Prandtl-Ishlinskii model is used, results of compensation have no contact with slopes under the assumption that backlash model has a symmetry structure and backlashes as well as slopes are all proportional with each other. As only proportion of reference input and output is related with slopes, the estimated parameters are reduced to only one. The results of simulation indicated that compensation effect of adaptive inverse control to hysteresis nonlinearity was much better when signal frequency was low ( less than 25Hz). The technology of active vibration isolation on power-train in China is still in the earlier phase of development. There are only few relevant reports abroad. The problem of the key technologies that are involved in active vibration isolation on power-train are not solved properly, which restricts the development of active vibration isolation in power-train. The study of this paper is helpful for the research and design of power-train vibration control system. It can also provide valuable reference for engineering design related with active vibration control system.更多还原