基于改进分形预测的板厚优化控制

Optimal control of strip thickness based on improved fractal prediction

中文关键词  分形预测,时滞评估,板厚控制,动态矩阵控制,混沌优化

英文关键词  fractal  prediction, time  delay estimation, strip  thickness control, dynamic  matrix

中文摘要

      针对热连轧机监控厚度自动控制(automatic gauge control, AGC)系统存在时滞、参数失配问题导致出口板 厚控制精度低和超调震荡问题, 首先, 提出基于综合小波互相关度的时滞评估方法来确定滞后步长; 然后, 引入分形 外推插值算法给出了考虑时滞的预测模型, 并利用混沌优化算法确定分形外推插值算法中的垂直尺度因子; 最后, 利用阶梯式动态矩阵控制(dynamic matrix control, DMC)优化PID控制器参数, 使得PID控制器参数能够根据不同工 况变化自适应调整. 仿真结果表明, 与传统监控AGC, Smith–AGC和IFEIP–AGC(改进分形外推插值预测, IFEIP)相 比, 本文方法有效地缓解了由时滞引起的出口板厚控制超调和震荡现象, 并且在有外部干扰及系统时滞参数失配情 况下, 具有较好的动静态特性.

英文摘要

      Aiming at low control accuracy and overshoot oscillation problem of the monitor automatic gauge control (AGC) in hot tandem mill due to time-delay and parameter mismatch problem, firstly, the method of time delay estimation based on the wavelet cross-correlation is proposed to determine the delay step; then, the fractal extrapolation interpolation algorithm is used to give the prediction model considering the time delay, and the vertical scale factor is deduced by using the chaos optimization algorithm; finally, PID controller parameters are optimized by using the ladder type dynamic matrix control (DMC) in order that they are adaptively adjusted according to the different working conditions. Compared with the traditional AGC, Smith–AGC and IFEIP–AGC (improved fracted expolotion prediction, IFEIP), the simulation results show that the proposed method can effectively alleviate control overshoot and oscillation phenomenon of exit strip thickness caused by time delay, and the improved system has better dynamic and static characteristics under the condition of external disturbance and system parameter mismatch.