Feedforward control concept: A feedforward controller primarily compensates for which class of changes acting on a process?

Introduction / Context:
In control strategy design, feedforward is a proactive approach: disturbances are measured upstream and counteracted before they affect the controlled variable. This contrasts with feedback, which reacts to errors after they occur.

Given Data / Assumptions:

• Process has measurable disturbance inputs (e.g., inlet composition, flow, temperature).
• Model (exact or approximate) relating disturbance to output exists.
• Controller can implement a compensating action based on disturbance measurement.

Concept / Approach:
Feedforward targets load disturbances. When the load changes, the controller injects a compensating move so the output barely deviates, ideally eliminating the need for corrective feedback. Set-point tracking is typically handled by the feedback loop; feedforward may be combined with feedback for robustness.

Step-by-Step Solution:

Verification / Alternative check:
In heat exchangers, measuring inlet temperature and adjusting steam flow preemptively is a classic feedforward application that reduces outlet temperature deviations.

Why Other Options Are Wrong:

• Set-point changes: Primarily a feedback duty, though model-based controllers can do both.
• Both equally: The defining purpose of feedforward is disturbance rejection.
• Neither / Sensor bias: Not the principal intent of feedforward architecture.

Common Pitfalls:
Relying on feedforward without feedback; model mismatch and unmeasured disturbances still require a feedback loop for correction.

Final Answer:
Load disturbances