【作者】 姚有领；

【导师】 费敏锐；

【作者基本信息】 上海大学 ， 控制理论与控制工程， 2008， 博士

【摘要】 板形和板厚是现代板带生产中两个非常重要的质量控制指标,板形、板厚质量控制水平的高低直接关系到板带钢制成品质量的优劣和板带钢市场销售的好坏,因此,板厚和板形控制功能是板带轧机自动控制系统中两个最主要的功能。板形、板厚两者之间相互关联、相互交叉、耦合程度严重。因此,两者构成了一个多变量、强耦合复杂控制系统。本文通过分析这一系统各变量之间耦合关系和各个变量的变化规律,研究了影响板形板厚两个重要质量指标的主要因素,建立了板形板厚综合控制系统控制模型,并针对山东莱钢1500mm热连轧带钢精轧六机架板形板厚控制要求,研究、设计了三种控制方法。根据板形板厚综合控制系统的特点:难以进行精确计算、难以建立精确数学模型、控制变量多、强耦合等,本文将基于遗传算法和神经网络的智能控制方法应用于板形板厚综合控制系统中,提高了板形板厚控制精度,主要所作的研究工作有:(1)通过对多变量神经网络控制器结构研究,在不变性原理的基础上提出了多变量串联补偿神经网络解耦控制方法。通过采用神经网络解耦补偿控制,在不影响系统控制功能和性能的前提下,实现了多变量之间的解耦,优化了控制系统的性能指标。(2)通过对标准遗传算法(Standard Genetic Algorithm简称SGA)的原理、控制参数的选择、遗传操作、编码方式等方面的分析、研究,针对SGA存在的易陷入局部最优、早熟以及多值参数优化中存在的二进制编码串过长等影响遗传算法的计算精度和运行效率的缺陷,对遗传算法进行改进,提出了基于实数编码的自适应竞争遗传算法(Adaptive Compete Genetic Algorithm简称ACGA)。采用ACGA、自适应遗传算法(Adaptive Genetic Algorithm简称AGA)和SGA对几个标准测试函数作了优化仿真,结果表明ACGA的性能要优于SGA和AGA的性能。同时,采用ACGA优化所设计的几种控制器的仿真和实际应用也表明ACGA能够较好地消除SGA所存在的缺陷,其学习效率、收敛速度等明显优于SGA和AGA。(3)针对广义预测控制的特点及实际应用情况,在总结原参考轨线的基础上,根据原参考轨线柔化系数不易精确确定、轨线参考性因人而异、准确度有待提高等不足,提出了一种新的参考轨线算法—自适应参考轨线,使得参考轨线跟踪系统输入输出的差值,提高了参考轨线精度。同时进一步研究了基于神经网络的预测控制算法,将神经网络与预测控制的融合,设计了一种神经网络预测控制器,改进了对多变量、非线性控制系统的预测控制性能,提高了1500mm热连轧精轧六机架板形板厚控制的实时性精度,增强了系统稳定性。(4)针对常规PID控制算法易于实现,但对系统参数变化适应性差的特点,将ACGA应用到PID控制器的参数在线优化中。通过仿真验证表明,本文所研究的智能控制方法对PID控制性能改进效果明显,不仅实现了PID参数的在线自整定,而且提高了系统的控制精度和响应速度。通过在精轧机上实际应用,表明基于ACGA的PID控制方法的性能明显优于传统PID控制效果。最后,将所研究的智能控制方法应用于山东莱钢集团1500mm热连轧带钢项目精轧六机架板形板厚综合控制系统中,通过对板形板厚实际控制效果比较情况看,基于ACGA多变量神经网络自适应解耦预测控制方法实时性和控制精度更好,而且控制系统设计不依赖于对象精确的数学模型,控制方法简单易行,易于实现,能够很好地满足当今板形板厚质量综合控制目标的要求。更多还原

【Abstract】 Strip Flatness and Gauge are two very important quality control indices in the modern strip production line. The quality control level will directly influence the quality of finished products as well as the sale markets. Therefore, the most important function of automatic control system of strip rolling mill consists of the control of the flatness and the gauge.The flatness and the gauge control, with the interlocking, intercrossing and strong coupling relation, constitute a complex multivariable strong coupling control system. By analyzing coupling relationship and variation law among all the variations in the system, the main factors of affecting the flatness and the gauge are analyzed, then the control model for strip quality integrated control system is established, and finally the three control methods are designed according to the flatness and the gauge control requirements of finishing mill 6 stand for Shan Dong Laiwu Steel 1500mm hot strip.The strip quality integrated control system has several features such as difficult to calculate exactly and to establish the accurate mathematical model, many control variations and strong coupling, etc. According to all these features, the neural network adaptive decoupling control theory is employed to the quality integrated control system, and several neural network decoupling controllers are designed as follows:(1) Through studying on the structural of the multivariable neural network controller, this paper presents a new multivariable tandem connection compensation neural network decoupling control method based on the invariance principle. Through adapting the neural network decoupling compensation control, the couple among the multivariations can be decoupled successfully and the performance indices are optimized under the conditions of maintaining the system intrinsic control function and intrinsic performance.(2) Special analysis and study is made on the standard genetic algorithm (SGA) for its principle, control parameters setting, genetic operation and coding method. Due to the standard GA with some deficiencies such as tendency to get into local optimization, prematurity, low calculation precision and operation efficiency owing to the existence of the too long binary character string in multi-valued parameter optimization process, etc, an improved real-code GA, namely Adaptive Competitive Genetic Algorithm (ACGA), is proposed. Comparing with the standard GA and the adaptive genetic algorithm (AGA), the simulation results demonstrate that ACGA have better performance. The several developed controllers are optimized by ACGA, the simulation results further show that ACGA not only overcomes the deficiencies of standard GA but also have better convergence rate and learning efficiency than standard GA and and AGA.(3) Due to difficult to determine softness factor and the poor adaptability of reference trajectory in prediction control, a new reference trajectory, namely adaptive reference trajectory algorithm, is presented. The prediction control algorithm based on neural network is described, which can be employed to the multivariable nonlinear objects due to the integration between neural network and prediction control. By adjusting the step, optimizing the weight and improving reference trajectory algorithm of Prediction control, the real time and control precision of the control system are improved, and the stability of the system is enhanced.(4) Although the conventional PID control algorithm is easy to achieve and good control performance, the adaptability for the variation of system parameters is weak. Therefore, the ACGA is applied to the online optimization for the parameters of the PID controller, and the simulation results show that the proposed algorithm not only achieves the online self-tune of PID parameters, but also improves the control precision and response speed. Moreover, the validity of proposed algorithm is further demonstrated by the application to the real finishing mill.Finally, the proposed intelligent control methods have been applied to the flatness and the gauge integrated control system of finishing mill 6 stand for Shan Dong Laiwu Steel 1500mm hot strip project, and the results show that the multivariable neural network adaptive decoupling predictive controller has the advantages of better adaptability for parameter variety, stronger interference rejection, better tracing input, and higher calculation and control precision. Furthermore, the controller can be easily design due to not relying on precise mathematic model and simple control algorithm, and can also fulfill strip quality integrated control requirements very well.更多还原