【作者】 刘显贵；

【导师】 陈无畏；

【作者基本信息】 合肥工业大学 ， 车辆工程， 2010， 博士

【摘要】 随着人们对汽车使用性能要求越来越高,通过控制汽车的侧向运动、垂向运动和纵向运动来提高汽车的操纵性、乘坐舒适性和制动性能的汽车主动控制技术成为汽车工程领域的研究热点。主动悬架系统(ASS)能根据路面状况调整悬架的阻尼或弹簧刚度从而提高汽车的平顺性;电动助力转向系统(EPS)根据不同车速提供不同助力力矩改善汽车的操纵性能;防抱死制动系统(ABS)通过防止汽车车轮在制动过程中抱死改善汽车的制动性能。然而,在研究这些主动控制系统时大多数文献只是注重其控制特性,而对控制系统本身的稳定性问题涉及甚少。在实际的EPS、ASS和ABS等汽车主动控制系统中,由于系统的非线性、外部环境的复杂性造成的不确定性以及系统本身时滞等因素,常常导致控制系统不稳定而影响系统的实际功能,因此在研究汽车主动控制系统的特性的同时,保证设计的控制系统的稳定应引起足够重视。同时,在设计单个主动控制系统时,往往是按照各自不同的性能指标进行设计的,而不同系统间往往存在的动力学耦合关系造成整车系统并不一定具有良好的综合性能。因此本文为了进一步提高汽车的综合性能,在研究控制子系统稳定性的基础上,基于改善各控制子系统性能,提高整车综合性能,进行底盘系统集成控制研究显然也是十分必要的。本文从汽车动力学系统理论分析角度出发,结合现代控制理论,对底盘关键子系统及其集成控制系统的控制特性、子系统的时滞稳定性进行了研究,将CAN总线技术应用到集成控制系统中,保证了良好的通讯性能和系统抗干扰性能。具体主要包括以下内容:(1)首先回顾了底盘主动控制三大关键子系统(EPS、ABS和ASS)的研究现状。随后对控制系统稳定性问题的必要性和研究现状作了介绍,并分析了底盘集成控制的研究背景、研究现状等问题,最后给出了本文的主要研究内容和创新点。(2)以半车为研究对象,对EPS、ABS、ASS分别建模的基础上,采用不同控制算法,进行各子控制系统设计并在MATLAB/SIMULINK平台进行仿真计算和控制特性分析。(3)针对控制子系统中普遍存在的时滞对系统稳定性的影响,本文采用参数依赖的自由权矩阵的方法和LMI方法导出了时滞系统一个新的鲁棒稳定的充分条件,并通过该稳定性条件对主动悬架控制系统和电动助力转向系统进行了基于时滞分析的系统稳定性评价,由于该稳定性条件和传统的稳定性准则相比具有更小的保守性,使控制子系统的鲁棒稳定性得到更好的保证。(4)为改善整车动力学特性,提高汽车的综合性能,对底盘两系统集成控制就进行了仿真研究。首先在建立整车系统动力学模型的基础上,确定全局控制指标,设计了H∞鲁棒控制器,对EPS系统与ASS系统进行了集中式集成控制;然后针对集中式集成控制存在的问题,在控制体系结构上作了进一步改进,在分析ABS、EPS子系统运动耦合关系的基础上,设计出各子系统控制器和集成系统控制器,对ABS与EPS系统进行分层集散控制。结果表明:汽车综合性能得到改善,而且集散控制相比集中式集成控制,具有建模简单,控制器设计的复杂程度低,集成控制系统稳定性高,具有开放性等优点。(5)基于LabVIEW平台进行了ABS与EPS系统硬件在环试验。通过设计ABS、EPS系统及集成控制器LabVIEW程序,采用PXI硬件系统进行了ABS与EPS两系统的硬件在环试验,进一步验证集成控制策略的有效性。(6)在设计CAN通讯系统的基础上,基于ARM7平台,进行了ABS和EPS集成控制器的开发,并进行实车道路试验。试验结果表明:基于CAN通讯的集成系统工作稳定,抗干扰能力强,集成控制策略正确有效,汽车底盘综合性能获得提高。(7)总结了全文的研究内容,对下一步的研究提出一些建议。更多还原

【Abstract】 In order to further enhance the overall performance of vehicle, active control technology of vehicle chassis through controlling lateral movement, vertical movement, and vertical movement of the vehicle to improve vehicle handling, ride comfort and braking performance is a research focus of vehicle dynamics in recent years. Suspension damping or spring stiffness are adjusted in active suspension system (ASS) according to road conditions to improve vehicle ride comfort; It provide different torque in electric power steering system (EPS) depending on different vehicle speed to improve handling performance; It prevent wheel car lock in anti-lock braking system (ABS) during braking to improve the vehicle braking performance; However, most of the literature focus only on the control characteristics of the active chassis control systems while the stability of the control system itself involves little. In fact, because of nonlinearity or uncertainties caused by the complexity of external environment and time delay of the system itself in EPS, ASS, and ABS, it lead to the control system instability and affect the normal function of the system. Therefore, it should be paid close attention ensuring the stability of the control system while studying the control characteristics of active control systems. Meanwhile, it often meet its different performance indicators in the designing of a single active chassis control system, but in integrated control system the vehicle does not necessarily have good overall performance because of dynamics coupling between systems. Therefore in order to further improve the overall performance of vehicles, it necessary to study integrated control of chassis systems in order to improve chassis dynamics coupling on the basis of studying stability of vehicle chassis control subsystems.In this paper, based on vehicle dynamics theory combined with modern robust control theory vehicle chassis control systems and it’s integrated control system has been studied. To ensure a good communication performance and system performance controller area network is carried out to integrated control system. It includes the following specifically:Firstly, in this paper mathematical model is established for electric power steering system (EPS)、anti-lock braking system(ABS) and active suspension system(ASS) based on semi-car model respectively, different control methods were adopted for controller design of subsystems, the simulation research was carried out.Secondly, It has been shown that the parameter-dependent stability condition is of less conservativeness than quadratic stability condition which requires a common Lyapunov function for the entire uncertain domain. the control system robust performance was evaluated and conservatism was analyzed for active suspension system. The results show that robustness of vehicle active suspension system was better guaranteed with a smaller conservatism.Thirdly, an integrated chassis control system was designed in two different control structure respectively: (ⅰ) The mathematical model of vehicle systems was established, then a global optimal control targets is determined, EPS and ASS were centralized to integrate control. (ⅱ) Take controllers designed for subsystems(EPS\ABS)as bottom controllers, upper coordinated controller was designed based on deeply analyzing the influences among EPS and ABS, upper controller was a decision-making controller, sensor signals were transmitted to upper controller through CAN bus; Simulation results show that vehicle synthesis performance is improved.Finally, Hard in Loop experiment was carried out based on LabVIEW development platform for integrated control system and real vehicle test was carried out based on integrated controllers’development of ABS and EPS using ARM7 and protel software. The result of real vehicle test and HIL(Hard-in-Loop) experiment proves that the integrated control logic we put forward is correct and feasible. It could not only apparently improve the performance of braking stability, but making steering portable as well.更多还原