Virtual design of a motor-toggle servomechanism with sliding mode-combined PID control

This paper deals with the issue of virtual design of a motor-toggle servomechanism for injection-molding machines. Based on the 3D CAD of multi-body system, a five-point-type toggle mechanism has been developed with clamping force build-up. Prior to controller design, open-loop responses are obtained to derive a transfer function. In order to accommodate mismatches between the real plant and the linear model used, a discrete-time sliding function is defined and combined with PID control. The uncertainty in the mass of moving platen and the Coulomb friction at pin joints are considered for robust motion control applications. Through the use of proposed control scheme, not only significant reduction in position error at moving platen but also clamping force build-up is achieved appropriately.