【作者】 王元；

【导师】 宋小文； 胡树根； 王耘；

【作者基本信息】 浙江大学 ， 机械设计及理论， 2008， 硕士

【摘要】 机油冷却器是内燃机润滑系统中重要的部件,其质量的好坏直接影响发动机的运行效果。机油冷却器的疲劳试验是其质量检测中重要的试验之一,随着生产厂家对试验控制精度要求的提高,本文结合电液比例技术与模糊PID控制策略,设计出了一套适用于疲劳性能脉冲试验台的控制系统,改善了控制效果,提高了系统的稳定性。论文主要工作内容如下:(1)介绍了机油冷却器和疲劳性能脉冲试验的基本原理,概述了电液比例技术的发展与特点,总结了目前电液比例控制策略的种类。(2)系统介绍了PID控制、模糊控制以及模糊PID控制的基本原理,详细叙述了模糊控制器的设计过程并结合实际分析了设计过程中关键问题的解决策略。(3)根据疲劳性能脉冲试验台的特点,建立了系统的数学模型。完成了适用于本套系统的模糊PID控制器的具体设计,详细介绍了模糊推理的数学过程并给出了计算的中间数据,为不同的模糊推理规则和清晰化方法提供了比较依据。(4)按照DCS的设计思想,设计了系统硬件的总体结构,完成了对控制系统硬件设备的选型和对中间控制电路的设计,并分析了其控制原理和各个部分的主要功能。(5)根据试验台的控制要求设计了系统上下位机的软件流程,实现了模糊PID控制参数调整的上位机程序和下位机控制算法程序。完成了上下位机以及下位机与温控器的通讯协议的制定。(6)在MATLAB/Simulink中,利用fuzzy logic toolbox设计了模糊PID控制器并搭建了系统的仿真模型,分别对PID控制和模糊PID控制的阶跃响应、传感器干扰以及正弦波响应进行了仿真,通过比较分析模糊PID控制器控制效果在超调量、稳定时间和抗干扰能力方面都优于传统的PID控制器,提高了疲劳脉冲试验系统的跟随能力和稳定性,并且在系统特性参数发生一定改变的情况下,模糊PID控制器仍可以保持较好的控制效果。更多还原

【Abstract】 Oil cooler is a key component in the lubrication system of I.C. engine, and its quality plays a great role in the engine’s performances. Fatigue property test is one of the quality tests for oil coolers. In order to meet the increasing demand on controlling accuracy during tests, a new control system for fatigue property pulsation test-bed is developed by combining electro hydraulic proportional technology and fuzzy PID control, which improves controlling effects, as well as the stability of the whole system.Main contents of this paper are as following:(1) The basic principles of oil cooler and fatigue property pulsation test were introduced, the developments and features of electro hydraulic proportional technology in general was discussed, and the presently different kinds of controlling strategy in electro hydraulic technology was summarized.(2) A group of fundamental principles including PID, fuzzy and fuzzy-PID were introduced comprehensively. The design process of fuzzy controller was presented in detail, and with facts the solving strategies to the vital problems bubbling up during the process were analyzed.(3) Mathematic model of the system was built up, according to the features of fatigue property pulsation bench. The design process of fuzzy-PID controller for the system was accomplished. Bring up the mathematic process of fuzzy deduction, and data during the calculation was proposed, which provides comparison with other fuzzy deductive rules.(4) The structure of the whole system was developed, according to the concept of DCS, and the selection for controlling hardware devices and design for the inner controlling circuits was completed, moreover, their controlling theories and functions of each part was analyzed.(5) In order to meet the controlling requirements, software flow process for upper and lower computer were designed, and programs based on the controlling parameter adjustments by fuzzy PID for them was accomplished. A communication agreement between up and down machines was made up, as well as down machine and temperature controllers.(6) Fuzzy PID controller was designed and simulation model of the system was built up by fuzzy logic toolbox in Matlab/Simulink, and the simulation of step response was performed, sensor interference and sine wave response under two separate controllers: PID and fuzzy PID, and effects of the two controllers were analyzed during the process. Based on the analysis, the control performance of Fuzzy-PID Controller is better than PID Controller’s in the aspect of reducing overshoot, shorten the dynamic regulating time. The system got a better following performance and stability, and in the situation of changing some performance parameters of the system, Fuzzy-PID Controller can still remain a better control effect.更多还原