Research On The Speed Control Of The Walking Beam Based On The Model-free Adaptive Control

At present, the walking beam furnace is widely used in the domestic hot-rolledproduction. With respect to the fixed beam, walking beam step up, forward, downand back, and transports the billet by the horizontal movement of translationmechanism and the vertical movement of the lift mechanism. Because the speed ofwalking beam changes complexly in the course of the campaign, the control of thespeed directly affects the heating effect of the billet, and the impact will cause thedeviation of the billet and the damages of the walking beams and fixed beams andother mechanical equipment. Therefore, improving the accuracy of the speedcontrol in the walking beam is very important.With the development of the technology of hydraulic, electro-hydraulicproportional control system is widely applied to the walking beam speed controlsystem, which has the excellent characteristics such as fast response, largepower-to-weight ratio and stiffness to anti-load. At present, there are already manyways to the electro-hydraulic proportional speed control system, such as PIDcontrol, adaptive control, fuzzy control and neural network control. However, theactual system is generally nonlinear time-varying system, it is difficult to establishthe precise mathematical model, but only the simplified system model can becreated, thus seriously affecting the accuracy of the control. Thus, the control effectof the conventional controllers is very undesirable by the affect of the imprecisesystem model in applications. Model-free control method is proposed for nonlinearproblems, and the method is simple for it is designed only using the input andoutput data of the controlled object, so the model-free controller has beensuccessfully applied to the light industry, environmental protection, electric powerand chemical industry, and has received a good control effect.In this paper, the walking beam furnace in Shandong steel mills is the researchobject. First, the nonlinear model of the hydraulic system of the walking beamfurnace is established, and the practicality of this model is verified compared withthe linear model. Then, the model-free adaptive control is applied to the walkingbeam speed control system, and in the Matlab/Simulink platform, the model-freeadaptive controller is developed, and the simulation shows the model-free adaptivecontrol system can control the speed changes of the walking beam well. Finally, based on the model-free adaptive control, the control algorithm is improved, thesimulation results show that the system has faster response after adopting theimproved control algorithm.