Learning-enhanced PI control of ram velocity in injection molding machines
This paper presents the development of a new learning enhanced PI control method for cyclical control of the ram velocity in injection molding machines. The overall structure of the control consists of a feedback and a feedforward component. The PI feedback control stabilizes the system, and the feedforward component incorporates an iterative learning control (ILC) algorithm to compensate for nonlinear/unknown dynamics and disturbances, thereby enhancing the performance achievable with feedback control alone. A simple and effective tuning method is further developed for the composite control structure which yields both the PI and ILC gains given only a first-order model. A nonlinear physical model derived for the process serves as the basis for the simulation study of the proposed control scheme. A comparison of the performance achieved with an optimally tuned PI control is also provided to highlight the advantages of the proposed control scheme.
pi control injection molding iterative learning control tracking control nonlinear systems