Injection Velocity Control in Injection Molding by Iterative Learning Control with Zero-phase Filtering

A feedforward and feedback control method based on iterative learning control(ILC) with zero-phase filtering is designed for injection velocity control.In this control method,ILC is used as the feedforward part to realize accurate trajectory tracking with information of the previous cycle,and proportional control is used as the feedback part to avoid disturbances appearing in the current cycle.In order to overcome bad learning transients in ILC,the convergence condition in frequency domain is derived,and then the implementation method for monotonic decreasing learning transients is described with zero-phase filtering.The experiments prove that the proposed method provides the ILC with a monotonic decreasing learning transient curve and meets the actual needs of injection velocity control.