A feedforward controller can be used only if:
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- the disturbance variable can be measured
- the disturbance variable can be manipulated
- the disturbance variable can be ignored
- regulatory control is not required
The Correct Option is A
Solution and Explanation
Step 1: Understand feedforward control.
It is a proactive control strategy that requires real-time measurement of the disturbance variable. Without knowing the disturbance value, the controller cannot compute the compensatory action.
Step 2: Evaluate options.
- (A) Correct — feedforward requires measurable disturbances.
- (B) Manipulating the disturbance is not part of feedforward strategy.
- (C) Ignoring disturbances defeats the purpose of feedforward control.
- (D) Regulatory control is often still required; feedforward is used in combination with feedback.
Conclusion: Only option (A) captures the requirement for feedforward control.
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