A generation step to develop steel rolling machine performance using an electro-hydraulic actuator and an online tuning modified-grey fuzzy PID controller

This paper presents an application of an electro-hydraulic actuator (EHA) and a novel control method - online tuning modified-Grey fuzzy PID controller (OTMGFPID) to a steel rolling machine (SRM) in POSCO Corp. in order to improve its working performance. In this SRM, the center position of the roller, which affects directly the rolling quality, is controlled by the EHA system instead of using a conventional servo hydraulic actuator (SHA). To enhance the center position control (CPC) performance, the OTMGFPID which is a combination of a main control unit, online tuning fuzzy PID controller (OTFPID), and an online tuning modified-Grey predictor (OTMGP) is designed for the EHA. The OTMGP with self tuning ability of its predictor step size based on fuzzy technique (called FPSS) is used to estimate the actual system output and to create a compensating control signal corresponding to the system perturbations, consequently, improving the control quality. The ability of using the EHA and OTMGFPID controller for the SRM with CPC is verified by simulated force control target of a press machine using EHA. Simulation results prove that the EHA as well as the proposed controller has strong potential to be applied for CPC of the SRM.