The master engineer knows when to apply gain scheduling (batch) versus cascade control (continuous). But the foundation remains:
Instead of modulating a valve continuously, you cycle a valve on/off. The ratio of on-time to off-time (duty cycle) determines the average energy input. Common for electric heaters in batch jacketed reactors. control loop foundation batch and continuous processes pdf
A disturbance is measured before it affects the PV. For example, measuring a change in inlet flow to a heat exchanger and pre-adjusting the steam valve. Combining feedback + feedforward is the gold standard for continuous processes. The master engineer knows when to apply gain