【作者】 陈林；

【导师】 贺建军；

【作者基本信息】 中南大学 ， 控制科学与工程， 2013， 硕士

【摘要】 大型立式淬火炉是为航空航天等领域生产高强度铝合金锻件的重要热处理装备。其体积庞大、结构复杂、多种传热方式并存,建立分布参数系统模型非常困难,本文研究采用机理-参数辨识建模方法,建立大型立式淬火炉分布参数系统动态模型,为控制策略的研究奠定基础。主要研究成果如下：(1)基于热平衡原理,分析炉内传热过程,在柱面坐标系下,利用微元法建立炉内温度场数学模型,确定了大型立式淬火炉分布参数系统动态模型结构。(2)根据模型特点,提出了基于Haar小波逼近变换的大型立式淬火炉分布参数系统辨识算法。把Haar小波作为正交基函数,利用微分运算矩阵及其运算性质,将描述的分布参数系统偏微分方程模型转化为矩阵代数方程,利用在线递推最小二乘方法实时辨识模型参数。该算法推导过程中不需要考虑模型的初始条件与边界条件,免去了对偏微分方程进行多重积分运算的繁琐,降低了时间复杂度。(3)借助于Matlab仿真平台,对基于Haar小波变换的分布参数系统辨识算法进行验证,分析时间步长与空间步长对辨识精度的影响,仿真结果表明,该算法具有逼近度高、计算量小且能抑制噪音的特点。选用m=8的Haar小波,利用辨识算法,获得了模型参数,完成了对大型立式淬火炉温度分布参数系统的建模。更多还原

【Abstract】 Large-scale vertical quench furnace is a kind of critical equipment for thermal treatment of high-strength aluminum alloy forgings widely used in aerospace industry. It is very difficult to establish an accurately temperature field model because the structure of large-scale vertical quenching furnace is complex; many different types of heat transfer are combined; temperature distribution was distributed parameter characteristically. This paper used mechaismsim-parameters modeling method to establish a mathematical model of temperature filed and a distributed parameter systems dynamic model of large-scale vertical quench for the study of its control methods. The main research results of this paper are as follows:(1) It established a distributed parameter systems model of temperature fields and determined the system dynamic model structure by analysising the furnace heat transfer process and in accordance with the principles of the heat balance in the cylindrical coordinate system.(2) It proposed an identification algorithm based on Haar wavelets approximation transform. The detail method was:choosing Haar orthogonal wavelets as basic function and using its differential operational matrix and its properties, transferring the partial differential equation describing distributed parameter system control model to matrix algebra equation. On this basis the parameter on-line identification algorithm for temperature distributed parameter systems of large-scale vertical quench furnace was deduced according to method of Least Square. The proposed method doesn’t need to consider the initial conditions and boundary conditions and it was much simpler than other methods which made use of the integrated operational matrix.(3) Simulation experiments were carried on by MATLAB. Through analyzing simulation results, characteristic of influence on parameter identification precision from space and time step was obtained. The simulation result indicated that this parameter estimation algorithm was effective, easy to compute and could undermine the characteristics of the nosise.It could get the model paramenters.by using that identification algorithm. It got the model parameters by choosing the Haar wavelet of8-order and using the identification algorithm, and finished establishing the distributed parameter systems model.更多还原