1.8 Summary
You should now be able to formulate a control problem in terms of the following:
Control objective
Inputs (manipulated or disturbance)
Outputs (measured or unmeasured)
Constraints (hard or soft)
Operating characteristics (continuous, batch, semibatch)
Safety, environmental, and economic issues
Control structure (feedback, feedforward)
You should also be able to sketch control and instrumentation diagrams and control block diagrams. In addition, you should be able to recommend whether a control valve should be fail-open or fail-closed.
The following terms were introduced in this chapter:
Actuator
Air-to-close
Air-to-open
Algorithm
Control block diagram
Control valve
Controller
Digital
Fail-closed
Fail-open
Gain
Integrating process
Model
Process and instrumentation diagram
Process gain
Sensor
Setpoint
The abstract notions of states, inputs, outputs, and parameters were introduced and are covered in more detail in Chapter 2.