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Group: process control

topic root > Group: engineering


--related--
engineering
parallel processing
robots
-
analog processor
automation
real time systems
distributed process control
hard real time systems
laboratory computers
monitored variable
process control languages
self-regulating systems
servo programming
user maintenance

--referenced--
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topics n-r

Summary

Most controlled processes are very simple, requiring just a little logic to keep them working smoothly, but they do have critical conditions which can be both dangerous and destructive. Control is usually closed loop PI or PID control with fixed set points, but open loop table-driven control may be applicable. Noise, long feedback delays, and insufficient information can make control more difficult. There is a large literature on control mathematics for predicting future effects given the current condition and past control history. Control may be self-corrective allowing adaptation to process changes. Control is complicated by hardware modifications and partial shut downs for scheduled maintenance. (cbb 5/80)

Group members up

Topic: analog/digital conversion
Topic: alarm reporting
Topic: data acquisition
Topic: digital measurement
Topic: digital simulation of analog
Topic: graphs in process control
Topic: ladder diagram
Topic: logging data and events
Topic: PID control loop
Topic: process control systems
Topic: programmable controller
Topic: safety critical systems
Topic: supervisory process control
Subtopic: simulator up

Quote: solver-dependent, operational semantics for Simulink; includes numeric methods, continuous blocks, discrete-time blocks, variable step-size methods, and zero-crossing localization [bouiO6_2012]

Subtopic: time vs. measurement up

Quote: the standard approach for control engineering is to forecast the time evolution of the system and solve for the forecast; better to measure the desired condition; e.g., soft-boiled-egg vs. wait 3 minutes [tursWM9_1988]

Subtopic: simple controllers up

Quote: in most process plants, 80% of loops use simple PI analog controllers; most of these are never adjusted after tuning [instrumentcontrol]
Quote: example of sequencing a quenching bath; very simple logic [controleng]

Subtopic: controllers based on model up

Quote: if temperature and pressure are stable, an open loop with a look up table is as accurate as a closed loop [instrumentcontrol]
Quote: model reference control calculates the proper control action based on current control error and control effects; for long process lags [instrumentcontrol]

Subtopic: discrete control theory up

Quote: use discrete control theory (DCT) to automatically repair deadlocks; compute control logic offline; prevent deadlocks with lightweight, online safety checks [kellT12_2009]

Subtopic: feedforward control up

Quote: feedforward control predicts and compensates errors before they occur; needed for long process lags or response times [instrumentcontrol]

Subtopic: hierarchical control up

Quote: cascade control uses a hierarchy of control loops [instrumentcontrol]

Subtopic: tuning up

Quote: adaptive tuning automatically adjusts control parameters according to current process conditions [instrumentcontrol]

Related up

Group: parallel processing
Group: robots
-
Topic: analog processor
Topic: automation
Topic: real time systems
Topic: distributed process control
Topic: hard real time systems
Topic: laboratory computers
Topic: monitored variable
Topic: process control languages
Topic: self-regulating systems
Topic: servo programming
Topic: user maintenance

Subtopics up

controllers based on model
discrete control theory
feedforward control
hierarchical control
simple controllers
simulator
time vs. measurement
tuning

Updated barberCB 11/04
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