How do you detect a cross-section and move from following the main line to following the crossing line. In this series of video tutorials we are starting with a very simple solution that could work in most of the cases. It is especially useful for the FIRST LEGO League Trash Trek competition where there is such a section.
This second part continues with importing two previously developed in Episode 53 blocks into our program. With them we can for align to lines. We program the robot to align to the cross line and start following it.
(LEGO humans of course, not real humans :) ). Working on World Robotics Olympiad 2014 elementary challenge. Collecting modules, bringing them together and lifting them. A very funny and interesting competition that we would explore in this and the next video tutorials from the series
Collect the humans and clear them from the rocket launching region. This is rather straightforward as a task, but it requires a little bit of thinking if you want to do it without manipulators.
Showing the same run, but from a different angle. This allows you to see more of the way we sensors work and how exactly the robot positions itself.
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.