【作者】 杨慰；

【导师】 钟绍华； 严利群；

【作者基本信息】 武汉理工大学 ， 车辆工程， 2011， 硕士

【摘要】 汽车电动助力转向系统是近年来发展起来的一种新型助力转向系统,该系统是由电子控制单元根据传感器采集到的信号来控制助力电动机的运转,从而实现电动助力转向的功能和良好特性。EPS除了具备液压助力转向系统的转向轻便等优点外,还具有转向平稳、节能、环保等一系列特点,因此EPS取代液压助力转向系统是转向系统发展的必然趋势。控制策略是EPS的核心技术之一,因而对该内容进行研究与探讨具有重要的理论和实际意义。论文介绍了转向系统的发展过程、EPS的工作原理及主要特点,阐述了国内外在该领域的研究与应用现状。针对当前在EPS控制策略研究方面所存在的一些问题,确立了本文的总体研究内容和研究方法。在现有的文献资料基础上总结出EPS在操纵性能和路感方面的评价方法与评价指标。对EPS的结构进行适当简化,分析EPS工作时的受力情况,建立助力转向系统及各子系统的动力学模型。论文通过分析汽车和驾驶员对转向控制的要求与特点,确定了助力特性的基本要求。介绍了在电动助力转向控制中采用的助力控制、补偿控制、回正控制和阻尼控制等控制策略。在助力控制的研究中,分析并比较了直线助力、折线助力和曲线助力三种助力特性曲线的特性与优缺点,利用模糊控制方法确定了本文所应用的助力特性。论文总结了当前可被应用于EPS的几种控制策略,确定了本文中EPS的基本助力控制算法,在Matlab/Simulink中分别采用模糊控制和PID控制方法建立起电动助力转向整体系统和各子系统的控制策略仿真模型,并对其进行仿真分析,研究在各种信号输入下控制器的不同参数对系统响应的影响。结果表明,所采用的控制策略可反映和满足助力特性的要求。本文的研究内容为控制策略在EPS上的应用研究提供了理论基础和设计方法,具有实际指导意义。更多还原

【Abstract】 Electric Power Steering (EPS) system is a new developing technology of power steering system in automotive. The principle of EPS is that the assistant motor works according to the measured torque and vehicle signals so that power steering can be modified and the performance of steering can be perfect. Besides EPS has the light steering torque like Hydraulic Power Steering (HPS) system, it has many other advantages such as steering placidly, low energy consuming, environment protecting and so on. Therefore it is an absolute tendency that HPS is taken place by EPS. Control strategy is one of the most essential technologies of EPS, and it is significant in both academy and practice to take much research and development in this area.The thesis introduces the development of steering technology and the features of EPS including function, types and advantages, and summarizes the research status about the EPS control logic. The research content is confirmed based on the particular defects of the EPS control logic. Moreover, the method to evaluate the road feeling and handing stability is summarized based on the available materials. After kinematical analyses of the automotive steering system the torque and angel dynamic models are built and kinematical character of the automobile steer can be learned through the simulation, and then an EPS simulation model is finally built with the kinematical analysis.According to the need of the vehicle and the driver on steering control, the basic assist characteristic is confirmed. The assist control, the compensation control, the damp control and the return control are all adopted in the EPS model. In the research of the assist control, three kinds of assist control models are compared, and the basic assist control strategy is selected. The assist characteristic curve is designed by fuzzy control theory.Several control strategies that can be adopted in EPS are listed and compared. The algorithm of basic assist characteristic in this thesis is confirmed. The simulation model of control strategy is built respectively based on fuzzy control theory and PID control theory via the Matlab/Simulink software, and then the model is simulated in order to find out the factors and influences of outputs based on different inputs. The simulation infers that the control strategy of EPS built in the thesis can greatly inflect and meet the need of assist characteristic.Research of this thesis provides important theoretic foundations and design methods for development of EPS system. Such a study will be of significance in practice guiding.更多还原