Industrial Control Concepts
Process control, PID tuning, and automation strategies
A
3 terms
Adaptive Control
Control system automatically adjusting parameters based on changing process dynamics.
Anti-Windup
Technique preventing integral term accumulation when output saturates.
Auto-Tuning
Automatic determination of PID parameters through system identification tests.
B
2 terms
C
5 terms
Cascade Control
Control strategy where output of primary controller becomes setpoint for secondary controller.
Characterization
Modifying control valve response to linearize process behavior.
Closed Loop Control
Feedback control system measuring output and adjusting input to maintain setpoint.
Control Philosophy
Document defining overall control strategy and operational requirements.
Control Variable
CV
Controller output signal sent to final control element like valve or drive.
D
5 terms
Dead Time
Delay between control action and observable process response.
Deadband
Range where no control action occurs, preventing oscillation around setpoint.
Decoupling
Compensating for interactions between multiple control loops.
Derivative Time
Td
Time advance provided by derivative action predicting future error.
Disturbance Variable
DV
Uncontrolled factor affecting process that controller must compensate for.
F
2 terms
G
1 term
I
2 terms
M
2 terms
O
4 terms
Open Loop Control
Control without feedback where output doesn't influence control action.
Optimal Control
Control strategy minimizing cost function while meeting constraints.
Override Control
Selective control choosing between multiple controller outputs.
Overshoot
Maximum amount process variable exceeds setpoint during transient response.
P
3 terms
PID Control
PID
A control loop mechanism that continuously calculates an error value and applies correction based on proportional, integral, and derivative terms.
Process Variable
PV
Measured value being controlled such as temperature, pressure, or flow rate.
Proportional Band
PB
Range of error producing full controller output change, inverse of proportional gain.
R
3 terms
Ratio Control
Maintains constant ratio between two process variables like fuel and air flow.
Rise Time
Time for process variable to go from 10% to 90% of setpoint change.
Robust Control
Control maintaining performance despite model uncertainties.
S
7 terms
Setpoint
SP
Desired target value for the process variable in a control loop.
Settling Time
Time for process variable to reach and stay within specified band of setpoint.
Sliding Mode Control
Nonlinear control forcing system to slide along defined surface.
Smith Predictor
Control strategy compensating for dead time in process using internal model.
Split Range Control
Single controller output operating multiple valves in sequence for extended control range.
State Space Control
Modern control using mathematical model of system dynamics.
Steady State Error
Difference between setpoint and process variable after transients decay.