Module 4 : Time Response of discrete time systems

Lecture 1 : Time Response of discrete time systems

1.2.3 Type-2 system and acceleration error constant

Systems having a finite nonzero steady state error with a second order polynomial input (parabolic input) are called Type-2 systems. The acceleration error constant for a system is defined for a parabolic input.


where $ \displaystyle K_a=\lim_{z\rightarrow 1}\frac{(z-1)^{2}}{T^{2}}GH(z)$ is known as the acceleration error constant.

Table1 shows the steady state errors for different types of systems for different inputs.

Example 1: Calculate the steady state errors for unit step, unit ramp and unit parabolic inputs for the system shown in Figure 4.

Figure 4: Block Diagram for Example 1
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