3. Accuracy of servo systems

Consider the system shown in figure 36 , where e (t ) is the input and P (t ) is a disturbance.

The choice of components for this system must meet specifications for accuracy in response to the applied signals e (t ) and P (t ).

In servo system synthesis problems, error specifications are most often presented in one of the following forms:

• bounded static error (steady-state) ;

• zero static error with respect to a canonical input, e.g. step or ramp;

• bounded dynamic error for a class of inputs with given temporal characteristics.

Alternatively, one of the full criteria defined in paragraph