# Viva questions for a line follower robot

> Common viva questions for a line follower robot project with what a good answer must cover: sensors, PID, motor driver and testing.

Canonical: https://roboticsengineering.in/free-library/viva-questions-line-follower-robot/ | Published: 2026-11-03 | Updated: 2026-11-03

**For a line follower, examiners focus on the sensors, the control method and your tests.** Prepare answers from your own robot.

## Sensors

- **How does an IR sensor detect a line?** It sends infrared light and measures what returns; dark surfaces reflect less.
- **How did you set the threshold?** From raw readings over the line and over the floor.
- **How many sensors did you use and why?** More sensors give finer position information at the cost of pins.

## Control

- **What is the control method?** On-off, proportional or PID. Explain what error you compute.
- **What do P, I and D do?** P reacts to the present error, I removes steady offset, D damps the change. See [PID for a line follower](https://roboticsengineering.in/pid-control-line-follower-explained/).
- **How did you tune it?** Start with P, then add D, then I only if needed, with notes of each trial.

## Hardware

- **Why this motor driver?** Cover current, voltage drop and heat. See [L298N vs TB6612FNG](https://roboticsengineering.in/l298n-vs-tb6612fng/).
- **How did you choose the battery?** Use the [battery runtime calculator](https://roboticsengineering.in/robot-battery-runtime-calculator/).
- **What limits the speed of your robot?** Sensor update rate, motor speed and grip.

## Testing

- **What is the best lap time or success rate you measured?** Give numbers from your own tests only.
- **What failed and how did you fix it?** See [line follower sensors not detecting the line](https://roboticsengineering.in/fix/line-follower-sensors-not-detecting-the-line/).

## Related

[Free Library](https://roboticsengineering.in/free-library/), [Report template](https://roboticsengineering.in/free-library/robotics-project-report-template/), [Viva questions](https://roboticsengineering.in/free-library/viva-questions-for-robotics-projects/), [More viva questions](https://roboticsengineering.in/robotics-project-viva-questions/).

Last reviewed: November 2026. Free to copy and adapt for your own college work. Follow your department format first; its rules override this page.