Figure 9 9 shows a basic closed loop configuration with proportional. Figure 9 9 basic unit feedback closed loop system under p control. We looked at the operation of the closed loop system under proportional. Control before, and you are also familiar with the proportional control. Mode from lab 1, so this is just a recap. Consider an example where the process transfer function is as follows: The closed loop system transfer function is then calculated as: The critical gain can be calculated from routh hurwitz criterion as 10 and the resulting frequency of marginal oscillations is calculated as 1. 41 rad/sec. Working with high gain values is not satisfactory as well because of real life effects such as possible controller output saturation which makes the control less effective as the system is no longer linear. Figure 9 10 closed loop step response of the example system under p only.