PI Controller using Ziegler Nichols Tuning

The results of the experiments carried out for the self tuning PI controller using Ziegler Nichols method are shown. The upper plot shows the variations of the set point temperature (the black line) and the actual temperature (the green line) in the SBHS. The second plot shows the control effort and the third shows the fan input.

Figure 9.32: Results for Fan Input change from 50 to 100 given to Self Tuning PI Controller designed using Ziegler Nichols method

Even on encountering the fan input change, the temperature remains close to the set point. Notice the change in the controller behaviour on encountering the fan input change. Here, result for the fan input going from 100 to 50 is also shown.

Figure 9.33: Results for fan input change from 100 to 50 given to self tuning PI controller designed using Ziegler Nichols method

Here, a change in the control effort can be noticed. This change has been brought by the PI Controller to keept the temperature close to the set point.
From the above two results, it is clear that the self tuning controller designed with direct syntheis has successfully rejected the disturbance.
For comparison, corresponding results are also shown for conventional PI controllers designed using Ziegler Nichols tuning.

Figure 9.34: Results for the fan input change from 50 to 100 to conventional PI controller designed using Ziegler Nichols tuning

Figure 9.35: Results for the fan input change from 100 to 50 to conventional PI controller designed using Ziegler Nichols tuning