This paper is concerned for tracking control of displacement control system of continuous casting mold (CCM) driven by servo motor with time-varying load disturbance and parameter perturbation. To improve tracking performance of CCM system, a nonlinear tracking controller based on feedforward and feedback control strategy is presented. Firstly, the system model is established by analyzing the non-sinusoidal vibration device. Then, an extended state observer (ESO) based on fractional power function (FPF) is introduced to estimate the disturbances of the system, which mainly include the parameter uncertainties and time-varying load torque. Subsequently, a composite controller, which includes a feedforward controller based on ESO and a feedback controller based on sliding mode control (SMC), is derived for addressing the tracking issues. Finally, numerical results show that the proposed control strategy is more effective than a feedback controller based on SMC.
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