ITPEC FE Morning October 2019 Question 4
ITPEC FE Morning October 2019 — Question 4 of 80
Line-following robot control — determine motor speed adjustments based on sensor feedback.
The vehicle follows a black circle using two photo-reflective sensors (L, R):
- •More black under sensor → sensor value decreases
- •More white under sensor → sensor value increases
When Sensor L > Sensor R:
- L sees more white, R sees more black → line is closer to R side
- Vehicle drifted left of the line
- Correction: turn right → Motor L: Increase, Motor R: Decrease
When Sensor L < Sensor R:
- L sees more black, R sees more white → line is closer to L side
- Vehicle drifted right of the line
- Correction: turn left → Motor L: Decrease, Motor R: Increase
Answer: (b)
Why not others:
- (a) — same response for both cases (always increase L, decrease R), cannot correct in both directions
- (c) — reverses the correction logic (turns away from the line instead of toward it)
- (d) — same response for both cases (always decrease L, increase R), cannot correct in both directions
Key rule: To turn in a direction, slow down the motor on that side and speed up the opposite motor. The correction must be opposite for each sensor condition.
AI-generated — may contain errors
The original exam layout is preserved in the image so diagrams, formulas, tables, and code remain accurate.
This question comes from an official ITPEC past paper. ITPEC Practice is an independent study tool and is not affiliated with ITPEC. See the official FE past-paper collection or Report an issue.