Line Following

Line following is a method of autonomous movement in which the robot or UGV follows a line on the ground. The line layout can be a simple linear path between two points or scale up to a complex network of forks and waypoints. The line/tape must be placed beforehand (and maintained) and the robot’s autonomous movement is restricted to the predetermined fixed paths defined by the lines. With the lines placed:

• The positioning system only needs to track where the robot is on the line network instead of worrying about the entire space. Simple applications may not need a positioning system at all.
• Mapping is taken care of from the start and navigation between two points in the line network can be easily executed.
• The robot's path can be constructed in a way that avoids problems in advance (such as obstacles, stairs, and heavily trafficked areas). This simplifies or even eliminates the obstacle detection system, reducing sensor and software costs.
• Failsafes can kick in and stop the robot if it leaves the line.

The above points mean that line following is far easier and cheaper to develop than allowing the robot to freely roam in space.

Common approaches for detecting the line include optical sensors which detect the line color or magnetic sensors ([##ITEM2295## RoboteQ MGS1600GY Magnetic Guide Sensor]) which detect magnetic tape ([##ITEM2102 Magnetic Tape - Adhesive Backed 1 x 0.045 inch x 150 ft Roll). The robot drives forward at a fixed speed while using feedback control to turn left and right to keep itself centered on the line. The robot may incorporate a manual drive mode that allows it to move freely without the lines when driven by an operator.

Example Robots

The robot in this video is a customized IG32 Mecanum line follower that uses the RoboteQ MGS1600GY Magnetic Guide Sensor to follow magnetic tape on the ground. The robot demonstrates stopping at waypoints and selecting routes at forks.