The System Design And Experiment Research Of Strip’s Center Position Controller Based On Single-chip Microcomputer

The strip-offline may occur in cold rolling mill process because of the differences between supplied coil, the different roughness of roller surface, inaccurate process of roller, unparallel axial direction of transfer roller and tension fluctuation of strip steel. Therefore, it is significant to design a strip center position controller with high precision and high real-time performance. This paper is based on the project of Reforming Shan Haiguan Tong Ye Strip 650 Reversible Cold Rolling Mill. Controlled object is decoiler and actuator is hydraulic device. Displacement sensor is used in the inner loop and photoelectric sensor is used in the outer loop. A strip steel center position controller is designed from hardware to software.8 bit PIC single-chip PIC18F6620 is used as the main control chip. This single-chip with high antijamming capability is suitable for the rolling status which has many interference sources and bad environment. Digital input and output interface circuits, analog input and output interface circuits and human machine interface circuits are designed based on the center position system’s process requirement. Hardware antijamming measures are emphasized in this thesis.Interface program is accomplished based on MPLAB software and interface program is testified to be correct. Man-machine interactive function is accomplished and operating people can select center position pattern, set parameters, diagnose, etc. Control algorithm is Fuzzy PID and we use simulation software to compare Fuzzy PID and PID algorithm. Then the main flow chart is built. Dual closed-loop is accomplished in the interrupt program. Meanwhile, Fuzzy PID algorithm was programmed into the controller and the control period is 10 ms.Finally, the experiment of open-loop controlling, stamping, inner-loop controlling and dual closed-loop controlling is conducted on the simulative decoiler test-bed. Through the experiment results, the control accuracy is ±0.5mm with dual closed-loop controlling and settling time is 0.35 s. The performance of the strip steel center position controller meets the need of the project.