【作者】 范长胜；

【导师】 郭艳玲；

【作者基本信息】 东北林业大学 ， 机械设计及理论， 2013， 博士

【摘要】 电动助力转向系统(EPS)是近年来兴起的一种新型动力转向装置,与液压转向助力装置相比较,由于其具有环保、节能及安装、调试、维修、维护方便等特点,在车辆领域应用越来越广泛。目前在国内电动助力转向系统已经在中、低端等级轿车车型中得到应用,但是电动助力转向系统在全地形车上的应用却很少见到相关文献报道。全地形车在各行各业中应用也越来越广泛,因为全地形车行驶的路面往往比较复杂,沙滩、草地、坑洼等路面都使得转向变得十分困难,因此全地形车电动助力转向系统的研究与开发对于提高驾驶的安全性及舒适性等方而具有一定的理论意义和工程应用价值。为实现全地形车转向系统电动助力功能,需要研究一种适用于全地形乍的电动转向助力控制系统,并需解决相关技术问题。本文重点解决三个问题,即助力特性曲线问题、硬件设计问题、软件设计问题。通过对全地形车电动助力转向系统结构特性分析、动力学分析,进行数学模型建立。其建模分析包括建立线性二自由度整车转向系统模型、助力电机模型和电动助力转向系统模型。并应用Matlab/Simulink软件进行了仿真验证,尤其对全地形车电动转向助力过程中的关键设计步骤进行了更为细致的仿真测试及模型验证,验证结果的分析研究可为后继全地形车电动助力转向的软件及硬件设计提供理论基础和数据参考。为了研究全地形车电动助力转向特性,对常见的直线型、折线型和曲线型三种助力曲线进行分析研究,并通过建立手力输出、车速和电机助力电流三者之间的三维曲线图,比较三者的优劣性能及在电动助力转向控制过程中三者之间的变化关系。经过分析研究,本文建立了复合型的电动转向助力曲线,其特点是既能达到直线型助力的快速响应要求,又能达到曲线型助力平顺性的要求,研究表明,复合型全地形车电动助力转向助力曲线设计更加合理。硬件设计是全地形车电动助力转向控制系统软件设计的平台,硬件设计的目的是为了开发出适合全地形车电动助力转向控制系统的硬件电路。在设计控制芯片选取均能达到-40℃-+125℃温度范围的设计要求,符合汽车级电子产品的温度范围要求。从吸收电流的性能分析中可知,所设计开发的全地形车电动助力转向控制系统的硬件电路从电源吸收的电流数值小,工作效率高,发热量少。硬件设计在为软件设计提供平台的同时,对全形车电动助力转向系统的开发与应用具有重要的实用价值。软件设计过程中对全地形车电动助力转向系统的控制策略、程序流程及故障诊断等进行了研究。控制策略是保证转向助力过程平顺、轻盈,在本文采用的控制策略为模糊自适应PID控制,设计了全地形车模糊自适应PID控制器,模糊控制的目的是使P、I、D参数能够随着输入量的变化进行在线修正,研究结果表明,在全地形车电动助力转向控制方面模糊自适应PID控制较传统PID控制具有更优的性能,使转向控制更加平稳、可靠。在确定控制策略后,依据复合型助力曲线并结合硬件设计,对本文所研究的内容进行软件程序设计,并通过程序流程的方式体现全地形车电动助力转向控制系统软件设计思想,在软件设计中给出了全地形车的故障诊断树及故障诊断表。软件设计对全形车电动助力转向系统的开发与应用同样具有重要的实用价值。本文设计研发的全地形车电动助力转向控制器,在国内相关电动助力转向系统检测机构进行了检测,从本文第六章可知各项指标均已达到行业检测标准。从检测结果(检测曲线或检测数据)分析可知,本文设计研究的全地形车电动助力转向控制系统助力曲线平滑,抖动小,检测数据结果较为理想。从助力曲线中也可知,助力上限电流达到了50A。通过助力电流结果分析及吸收电流结果分析,所研究开发的全地形车电动助力转向控制器发热量小,响应速度及跟随性较好,控制性能较为优越。本文在全地形车电动助力转向控制系统方面进行的理论分析、计算机仿真以及实验台架、实车测试结果吻合良妤,对于全地形车电动助力转向控制系统的基础研究、设计研发及其应用具有重要的理论意义和现实意义。更多还原

【Abstract】 Electric power steering system (EPS) is a new power steering device in recent years. Compared with hydraulic power steering deveice, it has the advantages of environmental protection, energy saving and installation, commissioning, repair, maintenance conmenience. More and more widely applied to the field of vehicle. At present EPS has been applied in low grade sedan in domestic. But the reports are rarely seen that the EPS is applied in the all terrain vehicle (ATV). ATV is more and more widely used in all walks of life. Because ATV traveling road surface are often more complicated. Beach, grassland, potholes all make the steering become very difficult. Therefore. ATV EPS research and development to improve the safety and comfort of driving have certain realistic and long-term significance.In order to realize electric assisted steering power function of ATV, need to study electric assisted steering power system to ATV and need to solve the key technical problems. This paper focus on three issues, namely, assist characteristic curve problem, hardware design problem and software design problems.Through the analyzed of system structure characteristics and dynamics, established mathematical model. The established model includes the linear two degrees of freedom vehicle steering system model, motor model and electric power steering. And using MATLAB/Simulink software to simulation and verification, Especially for ATV electric power steering key design steps in the assist process. The results can provide the theoretical basi reference data for the design of software and hardware.For the study of ATV electric power steering system, analyzed and researched three kinds of power curve on linear type, broken line and curve type. By established3D graph of the force output, speed and motor current to compare their performances and change relationship in the power steering control process.Through analysis and study, established the electric power steering composite type curves in the paper have the characteristics that rapid response like the linear power and steering smooth lile the curve type. Research shows that composite type assist curve design of ATV electric power steering is more reasonable.The hardware design is the software design plaform of ATV electric power steeing control system. The hardware design is intended to develop the hardware circuit which Applies to the ATV electric power steering control system. The control chip are selected to reach-40℃to+125℃temperature range in the design to meet the temperature range requirements of automotive electronic products. From the performance analysis of the absorption curent, the design of ATV steering control system hardware circuit is absorption current value small, work efficiency high and heat less. The hardware design not only provides a platform for software design, but also has important practical value for development and application of ATV eletric power steering system.The research of software design includes the control strategy, the program flow and fault diagnosis of ATV EPS. The control strategy ensures the steering process is smooth and light. Adopted control strategy is the fuzzy adaptive PID control in the paper and designed the fuzzy adaptive PID controller of ATV. Fuzzy cntrol is designed to make P I D parameters online correction changing with the input. Results shows that fuzzy adaptive PID control is better performance than traditional PID control of ATV electric power steering control system, it makes the steering control more stable and more reliable. Determined the control strategy, based the composite power curve and combined hardware design to design the software of ATV steering control system. Through the way of program flow to reflect the software design thought of ATV electric power steering control system. The fault tree and fault diagnosis chart are given in the software design. Software design has important practical value for the ATV electric power steering system development and application.The AVT electric power steering system controller that has been researched and developted was detected in the domestic relevant EPS detection mechanism. From the sixth chapter of this thesis, the indicators have reached the industry standards. From the test results (detection curve or data) analysis that power curve is smooth, jitter is small and test results are satisfactory. Also known from the power curve, that power limit current can up to50A. Through the results analysis of power current and absorption current, the heat is small, response speed and following is better, control performance is superior of the ATV electric power steering system controllemvhich researched and developted in the paper.The control system of theoretical analysis, computer simulation and experimental bench, real vehicle test results are in good agreement to the ATV electric power steering. It has important theoretical and practical significance for the based research, design and application to ATV electric power steering control system.更多还原