Lecture 10c: Steady-state System Tracking and System Stability Steady-state Tracking and System Type

In general, we would like to investigate the steady-state performance of a feedback system to disturbances and/or reference inputs that are not only constants, but can be expressed as arbitrary polynomials in time. Assuming that the system under consideration is stable, we classify such systems into system types depending to the polynomial degree for which the tracking error is constant. System types can be defined with respect to the reference input or disturbance. Let us consider the system with block diagram representation given by Figure 1. This block diagram can be simplified as shown in Figure 2, where we have ignored the disturbance signal. So, we will first concentrate on the steady-state tracking performance of the system to reference inputs, r(t). Now, let’s consider the following reference input