The line follower is one of the self operating robot that follows a line that drawn on the floor. The basic operations of the line following are as follows:
- Capture line position with optical sensors mounted at front end of the robot. Most use several number of photo-reflectors, and some leading use an image sensor for image processing. The line sensing procss requires high resolution and high robustness.
- Stear robot to track the line with any stearing mechanism. This is just a servo operation.
- Control speed according to the lane condition. Running speed is limited during passing a curve due to friction of the tire and the floor.
There are two line styles, white line on the black floor and black line on the white floor. Most adopting the first one in line width of between 15 and 25 mm.
- Mechanics
Right image shows bottom view and side view of the built line following robot. All mechanical and electrical parts are mounted on a proto board, and it also constitutes the chasis.
The line following robot is upheld in three points of two driving wheels and a free wheel. The driving wheels are made with a 7 mm dia ball bearing and a rubber tire. The free wheel is a 5 mm dia ball bearing attached loosely. To drive driving wheels, two tiny motors that are used for mobile phones, pager or any mobile equipment are used. Its shaft is pressed onto the tire with a spring plate, the output torque is transferred to the wheels.
The stearing mechanism is realized in differential drive that stear the robot by difference in rotation speed between the left wheel and the right wheel. It does not require any additional actuator, only controling the wheel speed will do.
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