Research On Strip Steel Guide Control Method Based On Sliding Mode Variable Structure

In the production line of the cold rolled strip, the strip steel guide control is extremely important. A good control on the strip steel guide can guarantee the continuous production of strip steel products. Therefore, researching on the strip steel guide control methods has practical significance.This thesis takes the cold rolling production line of a stainless steel mill as the background, and analyzes the strip steel guide phenomenon from the perspective of dynamic and sums up the reason of the off-tracking phenomenon. Then it introduces the principle of the strip steel guide and the function of the proportional effect correcting roller, integral effect rectifying roller and proportional integral effect correcting roller which are commonly used in the cold rolled strip steel industrial field. In addition, the thesis also figures out that the servo valve control hydraulic cylinder driving the steering-roll action is the most widely used and the most effective method undertaken for strip steel guide. At the same time, the thesis summaries the four key factors which can influence the guide ability of the guiding control system.Through analyzing the actuating mechanism of strip steel position servo-control system, three equations are obtained, which are electro hydraulic servo valve flow continuity equation, hydraulic cylinder flow continuity equation and external load force equation. After consolidation, the final mathematical model of the steel strip steel guide system is determined. As there are unfavorable factors in the servo valve of the controlled object and the hydraulic cylinder such as parameter perturbation, load disturbance and dead zone nonlinear, the thesis tries to adopt the sliding mode variable structure control method which has a strong robustness characteristic based on the exponential approach law.Finally, the thesis analyzes the control performance of the strip guide control system under the sliding mode variable structure through the simulation. The simulation results prove that compared to the conventional PID system, the system designed in this paper not only has better tracking settings and the anti-disturbance performance, but also can better adapt to the change in the controlled object parameters. In the end, it realizes the effective control of the complex strip steel position.