LAUSR

This study presents online-tuning approach using the moth flame optimization (MFO) algorithm to optimize the parameters of PID and modified PID (I-PD) controllers used in the split-range scheme to control the temperature of the mixing process. The performance of these controllers is investigated for the individual temperature setpoints in terms of settling time and compared with performances obtained using offline-tuning approach with the MFO algorithm. The simulation results show a significant improvement with online-tuning approach as compared to offline approach. To further improve the performance, this study proposes modifications in the original MFO algorithm in three phases: by changing the spiral path, by changing the initial population based on the opposition theory, and by a change in the selection of the flames for the updating mechanism. A new version of MFO algorithm is obtained by combining the above-mentioned modifications and used to tune the PID and I-PD controllers in both offline and online modes. Further, the new algorithm is tested for both the controllers with respect to the effect of system dynamics and the effect of process disturbance. The results obtained after validation show that the use of the new version of the MFO algorithm further improves the online tuning of both the controllers. The simulation results also clearly establish the superior performance of the modified PID (I-PD) controller over the PID controller under all conditions.