Gapped & Crossed Line Following. Part 9. Crossed Sections
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.
- #212
- 09 Mar 2016
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.
We would continue from the previous program where we used variables and we would change this to arrays.
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 tutorial we take a next step in programming reliable and consistent robots and this is to learn how to stop at a second intersection. We need this because most of the time when we want to reach a mission model on a robotics competition field, the model will be located away from us and we must use all kind of technique to reach it. In this tutorial - we stop at a second intersection.
The reason why you would want to watch this tutorial is because it demonstrates one of the most reliable ways to know where you are on the field and to accomplish missions successfully and this is aligning to a line. In the tutorial you will also see how a parallel program is developed and who parallel programs could be used in a meaningful way.
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.
The robot works on the field and decodes the different colours that represent the rows and the columns.
Instead of aligning forward as in the previous tutorial we felt there is a need to demonstrate how we could align backward when moving with the robot. This is not a rare case. The attachments of the robot are generally at the front of the robot and especially during FIRST LEGO League competitions the robot must move backward very often. It is helpful to have in your toolbox the ability to align backward with the robot.
In this video tutorial we demonstrate a really important concept for FIRST LEGO League competitions - you position the robot on the field with depending on timers and rotations. The issue with moving the robot for 10 seconds and then stopping is that every time it is in a different location. Same for rotations. The wheels will slip, the battery will change, something will happen and the robot will not be in the same place every time. This is not consistent and reliable.
On of the most precise ways to position on the FIRST LEGO League and other competition fields is to follow and align and in this tutorial we demonstrate exactly this - how consistent and reliable this method is to reach specific mission models. In this way you know that every time you will be at the right place, which is great.
In this 10 out of 10 tutorials we do 10 runs that demonstrated how consistent and reliable it is to stop at the second intersection. This is useful as it is one of the main ways to figure out how to position yourself on the field.
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.
We would look at the rules of the competition over our small model and we would start solving the field.
Continuing with the Proportional algorithm for following lines. Smooth and stable this is the first part of the PID.
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.