Figure 8 1 regions of dominant and insignificant poles/zeros in the. Chapter 7 dealt in detail with the relationship between the model parameters ( , , , and the quality of the system response (specifications such as po, settling. Later we will be able to tie these parameters the controller design. 8. 4 the effect of an additional pole on the 2nd order system. In cases where there are more than one or two poles close to the. Imaginary axis, a standard second order underdamped model will not be sufficient. The reduced order model may not be possible or it may require an additional real pole, or an additional pair of the complex poles. The additional pole will contribute more damping to the system response. This will reduce the percent overshoot, but at the same time it will slow the system response increasing rise time and.