State the main objectives of a control system. Discuss the terms - steady state regulation and transient regulation.
Answers
control system analysis and design it is important to consider the complete system response and to design controllers such that a satisfactory response is obtained for all time instants t
≥ to. Where-to stands for the initial time.
The study of a control system in time domain
essentially involves the evaluation of transient and
steady-state response of the system. The nature of transient response of a linear control system is revealed by any of the standard test signals – impulse
,step, ramp, parabola as this nature is depend upon
system poles only and not on the type of the input. It
is therefore sufficient to analyses the transient response to one of the standard test signals; a step is generally used for this purpose. However, if the system is unstable, the transient response will increase very quickly (exponentially) in time, and in the most cases the system will be practically unusable or even destroyed during the unstable transient response
In a control system, the input signal may contain spurious signals in addition to the true signal input, or there may be sources of noise within the closed loop system. This noise is generally in a band of frequencies above the dominant frequency band of the signals. Thus in order to reproduce the true signal and attenuate the noise, feedback control system is designed to have a moderate bandwidth. This impose a limit on reducing rise time & increasing Wn. Large Wn has a large bandwidth & will therefore allow the high frequency noise signal to affect the performance.
Steady-state response depends on both the
system and the type of input .from the steady-state
point of view the easiest input is generally a step.
Since it requires only maintaining the output at a
constant value once the transient is over. The system is asymptotically stable, and then the system response in the long run is determined by its steady state component only.