Non-interactive looper and strip tension control for hot finishing mill using nonlinear disturbance observer

Abstract

In this paper, we propose a non-interactive looper and strip tension control method for a hot finishing mill based on the nonlinear dynamic model. Using the NDOB (nonlinear disturbance observer), the nonlinear looper-tension dynamic system is decoupled into two independent SISO (single-input, single-output) subsystems, and moreover, the model uncertainties and the external disturbances generated from forward slip, strip thickness variation and outgoing strip speed are compensated. A modified TSM (terminal sliding mode) controller is utilized to control the looper angle while the output-feedback controller regulates the strip tension by adjusting the incoming roll speed. Hardware experiment with the 2-stand hardware looper simulator was performed to verify the effectiveness of the proposed approach.