Linefollowing

Linefollowing is the capability of a mobile device, usually a small robot, to detect a marked line on the floor and to follow it. The line is typically a high-contrast track, such as black on a light surface or white on a dark surface, and it provides a simple guide path for navigation.

Sensing methods rely on optical detectors that measure surface reflectivity. Infrared reflectance sensors use LEDs and photodiodes to sense the difference between line and background. Color or grayscale sensors and cameras can also be used, with image processing to identify the line and estimate its lateral position relative to the vehicle.

Control strategies interpret the line position as an error signal and generate motor commands to minimize deviation. Simple approaches include bang-bang (on/off) steering; more precise methods use proportional control or PID control, often with a small sensor array (left, center, right) to compute a continuous error and adjust wheel speeds.

Implementation typically involves a microcontroller or single-board computer, motor drivers, actuators, and the line-sensing hardware. Systems can operate with either two-wheel differential drive or tracked configurations. Lighting conditions and floor texture affect performance, and calibration may be required to maintain reliable line detection.

Applications include educational robotics, hobby projects, and line-guided transport in research or industry. Linefollowing also serves as a stepping stone for autonomous navigation concepts, such as map-based routing and obstacle avoidance, when combined with additional sensors.