Robust motion control of a clamp-cylinder for energy-saving injection moulding machines

This paper deals with the issue of robust motion control of a clamp-cylinder for injection moulding machines driven by a pair of speed-controlled fixed displacement pumps. As a fundamental step prior to tracking controller design, a feedback control system is suggested by implementing a position control loop in parallel with a system pressure control loop. A discrete-time sliding mode control scheme is developed for enhancing the tracking performance under inherent nonlinearities. Consequently, a significant reduction in tracking error is achieved for both position and pressure control applications.