Simple PID tuning using relay perturbation with error switching

A simple yet practical method of PID tuning using information acquired from open-loop relay switching operation was presented. The application was supported by an error switching block that limits the magnitude of error to match the one during the tuning procedure. The improvement of the proposed method was evaluated experimentally by comparing the same controller setting, one with the error switching and the other without. Error switching produced a much faster and accurate response during steady-state even with the presence of external disturbance. Without the error switching, the output was uncontrolled since error magnitude was large and unbounded.