Research On The Adaptive Control System Of Flatness For Tandem Cold Mill

Flatness is an important target for quality of the strip steel. And the flatness control is the key technology of modern rolling mills with high precision of flatness. Taking the adaptive flatness control system of tandem cold rolling mill as the research object, the thesis has done a lot of theoretical research and simulation analysis on the flatness pattern recognition, control strategy of executing machine as well as the adaptive flatness control system.The flatness pattern recognition is the key to the flatness control. For the problems of the traditional methods and the methods of fuzzy and neural network for flatness recognition, the thesis established the RBF model for flatness pattern recognition using Legendre multinomials as basic patterns, with only3input and3output signals based on Euclidean distances. And each internal layer of the network has a definite physics meaning. The flatness pattern recognition model designed above has a quick recognition speed and high precision, and it also has strong generalization capability. It is a simple and useful method for the flatness pattern recognition.Because of the non-linear character, time-variability and the severe interference of the flatness executing machine, firstly, the thesis established mechanism model of the flatness executing machine, and the high order model was reduced by the Routh order reduction method. It is hard to get a good control effect using the classical control method and modern control method based on the empirical model, so the thesis designed an STC (Self-tuning control) strategy based on BP neural network, it can overcomes the disadvantage influence brought in by nonlinearity in use of neural networks. Due to join the adaptive mechanism, it can effectively solve the model change and the negative influence of environmental disturbance. Consequently, the dynamic performance of the control system of the executing machine is improved.The thesis designed the flatness controller module and flatness calculating module based on the evaluation function of flatness executing machine. And based on the intelligent recognition method of flatness and the adaptive control strategy of flatness executing machine, the thesis has founded the adaptive flatness control system of the tandem cold mill. And the simulation analysis was done under the simulink environment in MATLAB. The result of the simulation shows that the adaptive flatness control system has the good features of quick response and small overshoot. It has strong self-learning and adaptive ability to the changes of system model and interference of the environment. And the precision of flatness can be controlled in the range of±3I. It meets the requirement of the rapidity and stable state precision. In a word, it is an effective control method for the flatness of tandem cold mill.