Friction compensation in the interstand looper of hot strip mills: a sliding mode control approach

Abstract In the paper, the problem of designing an innovative control scheme for the interstand looper in hot strip finishing mills is considered. Specifically, the proposed scheme enhances the performances of the standard Pi-based tension controllers in the presence of the unavoidable friction phenomena that strongly affect the mode of behavior of the looper mechanisms. Due to the highly nonlinear nature of the disturbances caused by friction, a control scheme is designed basing on sliding modes concepts. This solution has been considered owing to the well known robustness and simplicity characteristics of these nonlinear schemes. Extensive simulation results are provided showing the effectiveness of the proposed architecture in comparison with the standard one in a typical hot strip finishing mill.