Adaptive control of ram velocity for the injection moulding machine

This paper presents the design of an adaptive controller for the control of the ram velocity of an injection moulding machine, based on a physical nonlinear model which describes the filling phase in detail. Polynomial series are first used to simplify the mathematical model such that the system parameters and states are essentially separated. The errors arising from the approximation are reduced with the introduction of certain robustification terms into the control law representative of the residual effects. A sliding surface is subsequently defined and a self-tuning robust controller capable of achieving tight set-point regulation is proposed in which the control gains are tuned by an adaptive algorithm. The convergence property of the adaptive controller is proved. Finally, simulations are provided to evaluate the performance of the proposed control system.