Abstract: | The constraints on the PID gains, which are derived from the H∞ norm performance index by discretization of the frequency, are convex or concave depending on frequencies. This problem is a non‐convex problem, and a new method of approximating these constraints as adequate linear inequalities is proposed. Then, the optimal solution can be efficiently and successfully searched for by applying linear programming iteratively. This method is compared with methods based on barrier function and linear matrix inequality. Copyright © 2000 John Wiley & Sons, Ltd. |