Controller design of a steel billet mould oscillation system with iterative feedback tuning

In the continuous casting of steel billets, mould oscillation is a key process. The mould driven by a hydraulic cylinder is a big inertia system. Its trajectory is required to track a specific oscillation rule, but the tracking performance will be influenced by the molten steel weight. In this paper, dynamic pressure feedback (DPF) is proposed as compensation for the PID controller, to eliminate the adverse effect caused by the variation of the molten steel weight. The iterative feedback tuning (IFT) method is applied to tune the PID controller parameters and the DPF coefficient. In contrast to common IFT tuning structure, this paper designs a new scheme to estimate the cost function gradient with respect to the controller parameters. Numerical simulations and experimental results show the effectiveness of the DPF compensation strategy and the proposed parameter tuning method.