Which condition can cause a closed-loop system to oscillate?

• A. Over-correction of errors
• B. Under-correction
• C. High ambient temperature
• D. Absence of feedback

Answer: (A)

Oscillation in a closed-loop system happens when the response to an error is too strong. If the controller over-corrects, it pushes the output beyond the setpoint. The resulting error switches sign, prompting another large correction in the opposite direction, and this back-and-forth repeats. With high loop gain or very aggressive tuning, damping is reduced and sustained swings occur instead of a smooth settle.

Under-correction slows the response and leaves some steady error but doesn’t typically cause ongoing oscillations. High ambient temperature can affect sensors or actuators but doesn’t define the feedback dynamics that produce oscillations. Absence of feedback removes the loop entirely, so there’s no corrective action based on error and thus no controlled oscillation.