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.KEY WORDS: hot finishing mill; looper tension control; nonlinear disturbance observer; non-interactive control.

Control of Strip Tension in a Rolling Mill Based on Loopers and Impedance Control

“…The last line of Table 1 contains results for the triangular approximation that is used in many looper models (cf. Cheng et al, 2006;Noh et al, 2012;Price, 1973;Zhong and Wang, 2011). With this approximation, the strip is represented by two straight lines, which yields…”

“…Nonlinear control concepts based on backstepping and sliding mode control were reported by Hesketh et al (1998). Decoupling concepts for strip tension and looper dynamics were developed by Zhong and Wang (2011) based on feedback linearization and by Noh et al (2012) based on a nonlinear disturbance observer.…”

Parametric Robust Control of the Multivariable 2 × 2 Looper System in Steel Hot Rolling: A Comparison between Multivariable QFT and H∞

“…Although the present work is concerned with those techniques using a fixed linear robust controller in the frequency domain, it is worth mentioning that model based predictive controllers (MPC) [20][21][22][23] as well as non-linear techniques [24,25] have been applied to the looper system.…”

Looper-gauge Integrated Control in Hot Strip Finishing Mill Using Inverse Linear Quadratic Theory

“…Noh et al proposed a non-interactive looper angle and strip tension decoupling control method through nonlinear disturbance observer. 7) Based on feedback linearization, the looper angle and strip tension almost disturbance decoupling control scheme was proposed by Zhong and Wang. 8) Combining with a minimal-order disturbance observer and an on-line subspace identifier based on state space model for the looper system, Park and Hwang constructed the adaptive receding horizon controller.…”