【作者】 王磊；

【导师】 蹇兴东； 朱思洪；

【作者基本信息】 南京农业大学 ， 机械设计及理论， 2004， 硕士

【摘要】 空气悬架以其优良的减振性能，在汽车振动控制中得到越来越广泛的应用。本文建立了空气悬架两自由度振动控制模型，分析了空气弹簧刚度调节原理和控制特性，研制了空气弹簧刚度可调的电子控制单元。 本文讨论了以调节空气弹簧刚度的方式，改善汽车的行驶平顺性。在硬件系统研制过程中，应用EDA软件完成电路原理图的设计，分析了硬件系统的各个组成部分及其功能，选用ATMEL公司的AT89C51单片机作为微处理器，设计了滤波放大电路、采样／保持电路、A／D转换电路、看门狗电路、输出控制电路以及电源电路。在系统软件开发中，根据可靠与实用的原则，基于汽车振动控制系统的复杂非线性，采用结构化和模块化方法，设计了一种不依赖于精确数学模型的变参数模糊PID控制算法，应用模糊控制理论，在线调整增量式PID算法中的控制参数，改变空气弹簧的空气压力，进而调节空气弹簧的刚度。 本控制单元以空气弹簧的刚度作为控制量，把车身的垂直加速度信号作为目标量。控制单元将加速度传感器送入的加速度电信号进行一定的处理，并与设定的目标值相比较，得到空气弹簧刚度的调节趋势，通过控制电磁阀的通、断电，改变空气弹簧内的空气压力，实现无级调节空气弹簧刚度参数。通过单频激振实验验证，此空气弹簧电子控制单元可根据检测到的垂直加速度信号，及时改变空气弹簧内的空气压力，有效调节空气弹簧刚度，提高汽车的行驶平顺性。该电子控制单元具有响应速度快、抗干扰能力强、工作稳定可靠、体积小、价格低等优点。更多还原

【Abstract】 More and more application of air suspension are presented in automotive suspension system due to their performances. In the paper, two-degree-of-freedom vibration model of air suspension is built and stiffness adjustment theory and control characteristic of air suspension are discussed. On the basis, electronic control unit for air spring is developed.This paper discussed that the driving smoothness may be improved by altering stiffness of air spring. In the course of developing the hardware system, the circuits diagram is finished by the mean of EDA software. On the basis of analyzing function of hardware circuit, choose the AT89C51 as single chip microprocessor. Filter and amplifier circuit, sample and hold circuit, Analog-to-Digital conversion circuit, watchdog circuit, out port control circuit and power supply circuit were designed. In the course of software development, structure and modular design method is adopted in the principle of reliability and practice. With complex nonlinear of vehicle control system, variable parameter fuzzy-PID control algorithm was designed without mathematical precise model. Applying fuzzy control theory, it adjust parameters of increment PID algorithm on-line for efficiently controlling stiffness of air spring by altering ah" pressure in the air spring.This control unit take stiffness parameter of air spring as control value and acceleration in vertical vibration is looked as aim value. The control unit can processes electrical signal of acceleration measured by accelerometer in order to obtain altering trend of stiffness parameter of air spring. Air pressure can be changed by switching on and off valve so that stiffness parameter can may be continuously altered. Single frequency excitation experiments show that the control unit for air spring can efficiently alter stiffness parameter according to connected acceleration signal in vertical vibration and the driving smoothness is improved. It has some advantages, such as ability of anti-interference, fast response, high stability and reliability ,small size, low price.更多还原