The role of the controller series is mainly to achieve synchronization between rollers, uniform control of winding and unwinding. Its working principle can be divided into open loop, closed loop or free loop control system according to the loop; According to the monitoring method of different coils, it can be divided into ultrasonic type, floating roller type, tracking arm type and other control systems. The entire system consists mainly of controllers, detectors, brakes and clutches. The system is divided into direct control and indirect control. The control mode is manual control, semi-automatic mode, fully automatic and so on.