Sliding-mode dynamic surface control for MDF continuous hot pressing hydraulic system

In order to realize position tracking for Medium Density Fiberboard (MDF) continuous hot pressing electro-hydraulic servo system at the fixing thickness stage, a sliding-mode dynamic surface control strategy is proposed. Compared with backstepping method, dynamic surface control (DSC) introduces the first low-pass filters into the procedure to calculate derivatives of synthetic inputs, which simplifies the design. Owing to parameter variations and external load disturbances in the system, a sliding-mode surface is applied in the third subsystem to improve robustness. The appropriate Lyapunov function is constructed to prove that all signals of the closed-loop system are semi-globally uniformly ultimately bounded and the tracking error converges to zero asymptotically. The simulation results show that the proposed strategy can ensure the MDF thickness precision.