In the process of steel annealing, after the end of the heating stage, it enters the constant temperature stage, and the annealing process parameters are adjusted according to the process control curve of the constant temperature period. At this time, the fuzzy PID controller is used to control the constant temperature process parameters (by controlling the gas and air flow, i.e. the valve opening). According to the feedback signal obtained from the site, the values of the three control parameters of the PID controller are adjusted in real time to realize the on-line tuning of the PID controller parameters. The following will take the system parameters of continuous annealing furnace as the background, and take the process control of annealing constant temperature period under the given temperature mode as an example, the design method and steps of fuzzy PID controller for continuous annealing furnace are given.

PID control algorithm has good control effect and adaptability for most annealing furnace process, and it is still widely used. However, the manual adjustment of PID parameters not only requires skilled skills, but also takes a lot of time. At the same time, even if the PID parameters are well adjusted and the same set of fixed PID parameters are used to adapt to the whole process of the system, when the parameters of the control object change, the performance of the system will inevitably be affected. The fuzzy PID controller is used to monitor the waveform of output response on-line, and the index of control performance is obtained. The inference rule if ~ then model is established by using the adjustment experience knowledge. The fuzzy logic reasoning is used to adjust the PID parameters in real time, so that the PID controller can adapt to the change of controlled object and obtain good control performance.