JPS6448102A - Control method for industrial process - Google Patents

Abstract

PURPOSE:To quickly control a variable (p) with a high precision by immediately performing switching between the control due to final control element A and that due to the other in case of the process change. CONSTITUTION:An industrial process 1 is provided with a final control element A which controls two control variables (p) and (q) and a final control element B which controls only the control variable (p). A first regulator 2 outputs a controlled variable (px) for the control variable (p) and a second regulator 3 outputs a controlled variable qx for the control variable (q), and a comparing and computing element 4 compares the controlled variable px and the controlled variable (qx) with each other and outputs the smaller controlled variable (px) or (qx) as the controlled variable for the final control element A. For example, if the output (px) of the first regulator becomes lower than an operation end switching level (po) when the final control element A controls the controlled variable (q) and the final control element B controls the controlled variable (p), the controlled variable (px) is forcibly changed to a value smaller than the controlled variable (px) across a gap area C. Thus, the controlled variable (p) is immediately controlled by the final control element A without a lag.