Video tutorials -

• LEGO MINDSTORMS EV3

In this first part we stop at an algorithm that is the base for following lines and explains the basic idea for the proportion. A must watch if you want to understand the robot at its behaviour. At the end the program still wont work so check out Part 2 and Part 3 for the final steps.  

In this tutorial we present a way to align your robot to a black line. Go through common difficulties, that the teams face, when they need to align their robot, and provide a solution for them.

Continuing with the Proportional algorithm for following lines. Smooth and stable this is the first part of the PID.

Last part of the series. The final touch of the program makes sure that it works and is following the line with the LEGO Mindstorms EV3 Color Sensor in a smooth and fast way. 

This video lesson is a revised version of Episode #1. Matt Gipson requested it in a comment. Using the EV3-G software we have developed a very simple program for following a line with two LEGO MINDSTORMS color/light sensors.

In this tutorial we introduce the basic algorithm for following a line with one sensor and review the algorithm for quickly followwing a black line with one sensor, implementing both with the Mindstorms EV3 robotics kit.

We start a course for following a line with crosses and gaps. This is a challenge that one of the users at FLLCasts.com was trying to accomplish and asked us for advice. We present the whole challenge to you step-by-step. But first, let's also see the whole run of the line following algorithm. With this course, we also do an introduction of using State Machine as a programming pattern.

Very simple and basic introduction to the color sensor in the LEGO Mindstorms EV3 set. The first program is to stop at a line. Then we can move from stoping at line to counting lines and even more complex tasks.

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 a competition environment like the FIRST LEGO League (FLL) or World Robotics Olympiad (WRO) the color sensor is more than useful. It makes positioning on the field quite easy and precise. 

Looking at the field we must first think of a strategy of solving this line following problem. There are rules that the robot must follow and these rules should be programmed in the robot. 

Use the color sensor to count the lines and stop on the third line. We do not use the wait block for this.

Counting lines and stopping on the third is the subject of this video. It is important to know how to do this in order to conduct more than one experiment in STEM classes (if we consider that each line is an experiment)

The program from part 3 should be refactored and improved to make it easier to understand and support. We extract most of the repeatable behaviours in a loop and this reduces the size of the program three times in terms of the number of blocks used. 

The color sensors supports different modes of working. In this video we are working with the Reflected light, which is not actually the detected color. Most robotics sensors actually work with reflected light and you should definitely learn how to use this mode.

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.

We follow a line. We start from the Smooth Proportional Line Following program and modify it a little for this program. We follow the line with the middle sensor attached on port 2. 

This robot has a color sensor and this sensor is used for following lines. Additional Mindstorms EV3 sensors could be place on the robot, like a Gyro sensor or a second Color sensor.

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.

Tasks on using the LEGO EV3 Mindstorms Color sensor. Quite fun and useful for different STEM classes or just to get to know the sensor. 

Would you like to resolve all the problems with the light/color sensors that you have? And to make all of them work in a predictable, stable way even when using more than one MINDSTORMS colour sensors. 

When using Color sensors it is important to calibrate them depending on the light conditions in your venue. In this way, the calibrated sensor will show values between 0 and 100 independent of the light conditions. But using the default EV3 colour calibration available in the colour sensor block could lead to unpredicted problems that are difficult to track and resolved especially when used with multiple Color sensors. So in this series of tutorial we implement the calibration ourselves discussing the principles of colour sensor calibration.

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.

"What is the light in the room?" - should it even matter. You can use one program for all lighting conditions by calibrating the color/light sensor of the LEGO Mindstorms EV3/NXT robots. 

Next important state is Turn Right with our robot. This happens when we detect a line on the right. 

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.

Next state in our state machine programming pattern is the "Turn Left" state and the corresponding behaviour.