Variation in settling time with gain

A plot of settling time with variation in gain value is presented in Figure 23.2.

Figure 23.2 Variation of settling time with control gain

An exponential decrease in settling time is observed with increase in gain values. For example, increasing the gain to 200 results in a settling time response of 4 seconds while a gain value of 500 brings it to 2 seconds only.

Figure 23.3: Variation in damping ratio with control gain

Figure 23.3 shows that the damping ratio increases with increased gain value in almost linear fashion and reaches the critical value of 1 at a gain of 500. The increase in gain value beyond this point has little practical value as the system will be too sluggish due to overdamping.