Research On The Control Method Of MDF Thickness Continuous Flat Press

At present Medium Density Fiberboard (MDF) is a particle of recombinant composite board with domestic and overseas an extensive production and application, which has played a huge role on conservation of forest resources and meeting the needs of people’s lives. In the process of MDF production the hot pressing process is one of the main processes, the thickness or rectification for slab is completed in this process. Continuous flat press is its main production equipment and its ability to work and technical performance of the hot pressing process plays a decisive role. There are many hydraulic cylinders on the hot pressing board which is the key component of heat and pressure transfer. To enhance the capacity of precision controlling and target tracking of the hydraulic cylinder is one of the difficulties of continuous flat press control and also the key to ensure the quality of MDF.Aiming at the control problem of the single terminal displacement system, this thesis completed the mechanism of the backstepping control of adaptive sliding mode of hydraulic cylinder, and mainly completed the following innovation work:The thesis puts forward and establishs the mathematical model of single actuator hydraulic cylinder in hydraulic cylinder array and bases on this model, considering the factors that the viscoelastic of slab have obvious uncertainty and external disturbance force changes and other parameters to design the sliding mode backstepping controller. It uses the adaptive method to solve the weak vibration problem in sliding mode control of output to further improve the stability of the system. The controller has little dependence on the system mathematical model, it gets the control law expression by the backstepping control parameters of the adaptive sliding mode of the controller. It selects the appropriate Lyapunov function to prove that the position tracking error of the designed closed-loop system is convergent and the whole system is asymptotically stable. The thesis has respectively carried on the simulation to the traditional PID、adaptive fuzzy PID and adaptive sliding mode backstepping controller, The result shows:the method of adaptive sliding mode backstepping control can achieve the process requirements of continuous flat press in hot pressing and that the output of single hydraulic cylinder is stable and no overshoot, the method is applied to the field which MDF continuous flat press must strictly avoid output overshoot.