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Control System Design - Index | Book Contents |
Chapter 1
| Section 1.5
1. The Excitement of Control Engineering
1.5.6 Computing
In modern control systems, the connection between sensors and
actuators is invariably made via a computer of some sort. Thus,
computer issues are necessarily part of the overall design.
Current control systems use a variety of computational devices
including DCS's (Distributed Control Systems), PLC's (Programmable
Logic Controllers), and PC's (Personal Computers). In some cases,
these computer elements are rather limited with respect to the
facilities they offer. As with communication delays, computational
delays can be crucial to success or failure in the operation of
control systems. Determinism in timing is important, so a
multi-tasking real-time operating system may be required.
Another aspect of computing is that of numerical precision. We
know of several control systems that failed to meet the desired
performance specifications simply because of inadequate attention
to numerical issues. For this reason, we will devote some
attention to this issue in the sequel.
A final computer-based question in control concerns the ease of
design and implementation. Modern computer-aided tools for rapid
prototyping of control systems provide integrated environments for
control-system modeling, design, simulation and implementation.
These pictures to real-time code facilities have allowed
development times for advanced control algorithms to be reduced
from many months to periods on the order of days or, in some
cases, hours.
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