Consider IMC tuning to improve controller performance

The IMC-PID tuning rules reduce the tuning process to the selection of one tuning parameter as opposed to three. In addition, the single parameter is directly related to the closed-loop speed of response and robustness. Process models can be developed directly from open-loop tests or combinations of tests and first-principle equations. Disturbance rejection can be significantly improved for long time-constant-to-deadtime processes by assuming they are deadtime-plus-integrator forms. Finally, the rules are being successfully applied to industrial processes. The first example given illustrated how the application of the rules quickly led to high-quality tuning parameters for a troublesome level control loop. The second illustrated how the rules were applied to obtain very responsive tuning for control of composition for a high-purity distillation column.