Topic: digital simulation of analog

topics > engineering > Group: process control

analog processor
analog/digital conversion
digital measurement
discrete vs. continuous
PID control loop


Most control systems still use analog control methods because of their speed, known technology, low cost, and continuous values. But the wide spread development of microcomputers is encouraging digital control. Typically a digital computer will simulate an analog controller, sampling input values, doing computation and providing a new output value. The non-continuous nature of digital control causes some difficulties in situations requiring rapid response time. Digital simulation is very new to a field that is well defined. It does not improve performance of most control loops. Reliability requirements often force analog backup control. (cbb 5/80)
Subtopic: history up

QuoteRef: controleng ;;1/76 note: Control Eng. control products review has no software entry as of Jan/76.
QuoteRef: controleng ;;1/77 note: digital systems section started 1/77
Quote: in 1978, most control systems continue to be analog; either electronic or pneumatic [»instrumentcontrol]

Subtopic: digital controller up

Quote: direct digital control generally model conventional analog, proportional, PID controllers [»controleng]
Quote: a digital controller repeats sufficiently often to model a continuous-acting analog controller [»fishJ10_1978]
Quote: if data sampling is less than twice the highest frequency, can get periodic, false beat notes [»instrumentcontrol]
QuoteRef: controleng ;;1/77 24 Bristol EH: "Available DDC algorithms are frequently worse than the analog controller. Due to long sampling time and poor design
QuoteRef: controleng ;;1/77 24 Bristol eh: presents a direct control (DDC) algorithm equivalent to analog controllers.

Related Topics up

Topic: analog processor (5 items)
Topic: analog/digital conversion (3 items)
Topic: digital measurement (1 item)
Topic: discrete vs. continuous (47 items)
Topic: PID control loop
(5 items)

Updated barberCB 4/04
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