基于模糊自适应模型的热镀锌锌层厚度控制

Thickness control of hot dip galvanizing coating based on fuzzy adaptive model

针对锌层厚度控制过程中存在时变大滞后、非线性和多变量干扰而难以实现精确控制的问题,提出基于模糊自适应模型的前馈控制方法.通过分析锌厚与气刀压力、气刀距带钢距离和带钢速度的关系,提出具有预设控制功能的控制方法,能够快速响应过程参数(如线速度和目标锌厚)的变化.模糊自适应模型能够精确描述对象的非线性特征,而且在长期运行过程中,可以通过自适应调整模型参数来保持模型的精确性.从实际应用结果可以看出,与传统PID控制方法相比,提出的控制策略能稳定地减少锌层厚度偏差,提高镀层均匀性,满足提高产品表面质量和节省锌原料的实际需求.

In order to solve the problem that the accurate control is difficult to be realized because of large time-varying delay,nonlinearity and multivariable disturbance in the thickness control process of galvanizing coating,a feedforward control method based on fuzzy adaptive model was proposed.Through analyzing the relationships between thickness of galvanizing coating,pressure of air knife,distance of air knife to strip steel and speed of strip steel,a control method with presupposed control function was proposed.The proposed control method can quickly respond the change of such process parameters as the line speed and the objective thickness of galvanizing coating.The fuzzy adaptive model can accurately describe the nonlinear characteristics of the object.In addition,the accuracy of the model can be maintained through adaptively adjusting the parameters of the model in long-time running process.It can be noted from the pratical application results that compared with the traditional PID control method,the proposed control strategy can steadily reduce the deviation in the thickness of galvanizing coating,improve the uniformity of the coating,and meet the pratical demands in enhancing the surface quality of products and saving the usage amount of zinc.