28-11-2012, 06:14 PM
Sampled-Data/Discrete-Time Systems
Z-Transform.ppt (Size: 911.5 KB / Downloads: 24)
. Introduction
A system that contains one or more components that accept inputs only at discrete time intervals and/or changes its output only at discrete time instants, is a discrete-time system.
Such systems may arise
Naturally, e.g., Economic systems, Population studies.
By necessity, as a component may inherently be in discrete-time (although the plant is continuous), e.g., a radar-antenna systems.
By choice, as in a computer-controlled systems.
Advantages of digital control over analog control:
More reliable; less susceptible to aging and environmental variations.
Less sensitive to noise.
Digital processors are compact and light-weight. Single chip Microprocessors and/or DSPs may be used.
Implementation of controller in software provides great flexibility.
Disadvantages:
Limitations in computing speed causes delay that may lead to instability.
Finite word length may translate into loss of resolution and even in stability.
Initial cost may be higher.