Motors can be placed in opposite directions... opposite .. directions. Robo-builders might have difficulties imagining it so we have build one. One of the motors facing forward, the other backward. It is interesting how this robot turns.
Let's implement a more advanced program for this robot to learn how to use with motors in opposite directions - and this is to implement the Proportional Line Following algorithm.
We would look at the rules of the competition over our small model and we would start solving the field.
The robot works on the field and decodes the different colours that represent the rows and the columns.
We would continue from the previous program where we used variables and we would change this to arrays.
We list the number of decisions that the robot is making while following the line. Then, we group them and decide on the number of sensors to be used.
It's inevitable. While following this gapped line we would reach a gap. The robot must somehow understand that there is a gap and must make a decision on what to do. For detecting the gap we use the Rotation Sensor. Not the most popular, but very convenient in many cases. Check out the video.
We've detected the gap. It's time to move over it. This is difficult because we have to detect where the line is after the 0.1 meters gap on the line following field.
Next important state is Turn Right with our robot. This happens when we detect a line on the right.
We can Turn Right. We can Turn Left. How do we decide which way to go if there are lines both to the left and to the right. Check out the video.
All worked as expected, up until know because the robot got lost. This happens when we turn right and the line does not continue to the right. Now the robot must somehow understand that it is "lost" and escape.
The final video from the course. The robot escapes the state where it is lost. This happens if it can not continue in any direction.
We extract the Proportional Line Following algorithm into a new block with parameters. This allows us to experiment with the Threshold, Constant Speed and Relaxation Coefficient. You can now easily use the block in you other programs without having to implement it.
In this video we look at the robotics mechanism for dropping the different blocks into the different region on the World Robotics Olympiad 2013 field.
After we have introduced a menu in the previous video, this video focuses on storing the values in an array. It presents a basic use of arrays.