Slab Thickness Deviation Rectification Of MDF Continuous Press Based On Adaptive Sliding Back Stepping

In the process of medium density fiberboard (MDF) continuous production process, the hot pressing technology is the key link, which directly determines the quality of MDF products. The continuous flat press is a main equipment of the hot pressing process, ability and technical performance of the continuous flat press plays a decisive role to complete hot pressing process. multi row and multi column hydraulic cylinder are distributed on the hot pressing board as a key component of the heat transfer and pressure transmission, due to individual differences and different disturbances in the work process, the stable process that they achieves can appear synchronous phenomenon, which cause uneven thickness of MDF. This dissertation aimed at the hydraulic cylinder array motion control problem, researched the control method of hydraulic cylinder array from the individual to the perspective of the overall control, formed plate thickness deviation sliding mode adaptive backstepping control mechanism for MDF continuous flat pressing.Aiming at the tracking control problem of single terminal displacement control system, the mathematical model of hydraulic cylinder servo control system is established, considering slab viscoelastic and other parameters those have obvious uncertainties, and the sliding mode backstepping controller is designed. The adaptive method solves weak chattering problem of sliding mode control output, and further improve the system stability. The design of adaptive sliding mode backstepping control parameters of displacement control system, get the expression of control law. The simulation results shows that adaptive sliding mode back stepping control method realizes stable and without overshoot displacement output of single terminal displacement control system, is suitable for MDF continuous flat press process.For the synchronous output control problem of multiple actors (multiple hydraulic cylinder array), the mathematical models of multi power terminal displacement control system, and hydraulic cylinder array are proposed. According to synchronization output problem of the hydraulic cylinder array, adaptive sliding mode backstepping controller is designed for multi actuator hydraulic cylinder, the controller has less dependence on bounded disturbance whether or not known, can eliminate synchronization error which is caused by disturbance signal and single terminal displacement control system parameters there are differences, can achieve consistent of multi terminal synchronous output control objectives within the shot time. Selecting the Lyapunov function proved that the position tracking error of closed-loop system is convergent, so the whole system is asymptotically stable. The simulation result shows that adaptive sliding mode backstepping controller can not only eliminate the weak chattering phenomenon, and can achieve without overshoot smoothly control, synchronous output realization of each actuator, output error being within the allowable range.Grating displacement sensors are regarded as detecting component of MDF thickness. Moreover, according to the detection system requirements, S 7-400 CPU412 PLC is selected as the main control unit of testing system, to complete the hardware system design of the MDF thickness detection system. MDF continuous flat pressing plate thickness deviation adaptive control mechanism are put forward. The method can realize the automatic correction of MDF thickness. Furthermore, according to the that based on the experiment of slab thickness deviation test, and the hydraulic cylinder array overall output has good consistency, and it also has a certain reference value for the MDF continuous flat plate thickness control research.