【作者】 张超；

【导师】 朱思洪；

【作者基本信息】 南京农业大学 ， 机械设计及理论， 2008， 硕士

【摘要】 CAN总线是目前流行的总线技术之一,是一种基于微控制器的网络。CAN总线具有多主工作方式、传输速度快、距离远、自动解决总线竞争、自动重发功能、纠错能力强等特点,并已被广泛应用到汽车工业、自动控制、航空航天、过程控制、机械工业、纺织机械、机器人、数控机床、农用机械、医疗器械等领域。通过广泛查阅国内外拖拉机电液悬挂系统发展文献,以及CAN总线在农业机械上应用现状的资料,本文针对拖拉机液压悬挂系统部分的特性,提出了基于CAN总线的拖拉机电液悬挂控制系统。文中首先介绍了拖拉机悬挂系统和CAN总线的发展情况,说明了本课题的研究内容及其意义。接着针对CAN总线的特点,重点研究分析了CAN协议的分层结构、技术规范、报文发送、帧结构、物理层以及CAN总线的错误处理等。然后是对拖拉机电液悬挂控制系统进行了分析,推导出了拖拉机电液悬挂液压控制系统的数学模型,并利用MATLAB仿真工具分析了采用PID控制策略对该被控系统的校正。最后以PIC16F877A单片机为核心,设计开发了电液悬挂系统的单片机控制器。其中在主控制器上主要实现采样、PID控制、CAN通讯、PWM信号和开关信号的输出控制等的功能;操作显示面板则实现采样、CAN通讯、四位LED显示、键盘扫描和处理功能。在单片机控制系统的设计开发过程中,硬件部分是利用PROTEL99SE软件设计出了电路原理和PCB板。软件部分借助于MPLAB集成开发环境软件包进行编程和离线仿真。本控制系统在试验室进行了部分试验,通过试验结果表明,本文设计的控制系统达到了一定的控制要求,具有较好的应用前景和推广价值。更多还原

【Abstract】 CAN(Controller Area Network) is one of the most popular field bus, the net built on the microcontroller, which has so many advantages as multi-master mode, high transmission speed, long distance, automatic solving bus competition, automatic retransmission, strong correcting ability and so on. It has already been put in wide use in fields like automobile industry, automatic control, aeronautics and astronautics, process control, machine industry, textile machinery, robot, agricultural machinery, medical equipment.This article advances a tractor electronic hydraulic hitch system based on the CAN bus on the ground of the characteristics of the hitch system, in reference to the latest literature of theory and application.Firstly, this treatise illustrates the content and significance of this topic by a brief introduction of a tractor electronic hydraulic hitch system and CAN bus. Furthermore, focuses on the technology criterion, message transmission, frame structure, physical layer and error handling.Moreover, the reasonability of substituting the electronic hydraulic hitch system for the traditional is looked through and a mathematical model is developed to simulate PID by MATLAB.Finally, with the core of PIC16F877A single-chip, single-chip controller of electronic hydraulic hitch system is established, in which the primary control board acts as sampling, PID controlling, CAN communication, PWM and switch signal outputting, while operating screen board works as sampling, CAN communication, 4-digit LED screening, scanning key-board and processing. Within this system, the hardware is designed in accordance with the electrical circuit principle of PROTEL 99SE and PCB board; the software is, by means of the integrated development environment MPLAB software assembling program and off-circuit simulation can be made. The controlling system has been tested partially in the lab, and the result implies that the system can meet the requirements and can be prosperous in practice.更多还原