Robust Control Techniques Applied to the Hot-Dip Galvanizing Process

Abstract

This paper presents new results to compute the time-delay margin of the hot-dip galvanizing control system. Compared to previous works on this issue, this paper considers a mathematical model of the plant with two inputs and one output. The inputs are used to regulate the output, which represents the Zinc mass coating of steel strip. To achieve this objective, a multivariable PI controller is used, this controller is tuned applying the well known Ziegler and Nichols method, and then the maximum time-delay is computed in order to guarantee the stability property of the close loop control system. The work bases its results on a transformation of the time-delay operator and it is performed in order to get a two variable polynomial; after this, to obtain the robust stability property, a result based on the Hurwitz matrix is applied.

New Algorithm Based on Sign Decomposition to Verify the Robust Stability Property for a Class of Linear Time-Delay Systems

“…For example, in [4][5][6] an analysis of robust stability for time-delay dynamical systems with parametric uncertainty in the mathematical model and in the time-delay is shown; in addition, the value set concept and the zero exclusion condition are used to verify the robust stability property of interval plants; see also [7,8]. In [9,10] the robust stabilization problem for a class of time-delay systems is considered where they involve parametric affine perturbations; in [11], new results to compute the time-delay of the hot-dip galvanizing control system are considered. In [12,13] the authors present a robust model predictive control for systems represented by Takagi-Sugeno models and this technique was applied to the continuous stirred tank reactor (CSTR).…”