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Group: process control
topics >
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
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
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)
Subtopic: controllers based on model
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: feedforward control
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: hierarchical control
Quote: feedforward control predicts and compensates errors before they occur; needed for long process lags or response times [»instrumentcontrol]
Subtopic: tuning
Quote: cascade control uses a hierarchy of control loops [»instrumentcontrol]
Quote: adaptive tuning automatically adjusts control parameters according to current process conditions [»instrumentcontrol]
Topic: analog/digital conversion (3 items)
Topic: alarm reporting (4 items)
Topic: data acquisition (8 items)
Topic: digital measurement (1 item)
Topic: digital simulation of analog (8 items)
Topic: graphs in process control (3 items)
Topic: ladder diagram (5 items)
Topic: logging data and events (17 items)
Topic: PID control loop (5 items)
Topic: process control systems (3 items)
Topic: programmable controller (9 items)
Topic: safety critical systems (32 items)
Topic: supervisory process control
(1 item)
Group: parallel processing (41 topics, 1125 quotes)
Group: robots (16 topics, 147 quotes)Topic: analog processor (5 items)
Topic: automation (15 items)
Topic: real time systems (14 items)
Topic: distributed process control (6 items)
Topic: hard real time systems (64 items)
Topic: laboratory computers (2 items)
Topic: monitored variable (28 items)
Topic: process control languages (2 items)
Topic: self-regulating systems (23 items)
Topic: servo programming (6 items)
Topic: user maintenance
(13 items)