Stop the robot after the third line
Introduction
How to stop the robot after passing the third (or nth) line? This problem is very often encountered in FIRST Lego League (FLL) or in Rescue competitions. The problem is that the sensor reads continous data, and simple solution wont work.
This page gives to different solutions: (i) using timer or rotation angle to pass the lines and (ii) using flip-flop algorithm to count the black lines.
Robot
Almost any robot will do. We use Asimov 2/ Verne robot.
Sensors
One color sensor is needed.
Example Videos
Theory
Readings of the color sensor
The calibrated color sensor reads about 100 at white, and while passing the black line it reads about 0.
Using the timer/ rotation angle
By using the timer we can drive past the black line, and again look for the next black line. After finding the third one, we stop. This can be done in a loop, also. Usually, if you need to repeat the code, use a loop.
Using flip flop circuit
Example Code
Using the timer
Using flip flop circuit
Exercises
This course is supported by Meet and Code. The course is made in collaboration with Robotiikka- ja tiedekasvatus ry.
