Multiloop PI/PID control system improvement via adjusting the dominant pole or the peak amplitude ratio

Multiloop control systems designed by simple methods such as the biggest log-modulus tuning may be too sluggish or too oscillatory. Sluggish responses are due to dominant poles near the origin, and oscillatory responses are due to dominant poles with large imaginary parts or large peak amplitude ratios in the closed-loop systems. A method that adjusts such dominant poles and amplitude ratios through the continuation method is proposed. Several examples show that the improved multiloop control system can be obtained without resorting to complicated design methods.