Undamped oscillations are oured by:

Undamped oscillations are oured by a high gain and a long dead time. The high gain makes it likely that the response may overshoot the desired level. The long dead time allows the overshoot to reach a considerable value before the overshoot is corrected by the negative feedback mechanism. Thus, the oscillations continue. A good example of undamped oscillations is Cheyne - Stokes' breathing. SERVOMECHANISM: In some control systems, the set point is not a fixed entity. If the set point changes from time to time, the system is called a servomechanism. The stretch reflex which regulates muscle length is an example of a servo mechanism. The stretch reflex has a variable gain. The initial high gain increases the speed with which most of the response is completed. The low gain later reduces the oscillations in the response.