The LEGO Mindstorms EV3 set comes with two LARGE motors. But even though these motors look almost the same they are not quite the same. There are always some differences in their behaviour. If you have more than two motors, because you bought them or you won them somewhere at a competition, it is worth doing an experiment to find which pair of motors works best.
- #668
- 09 Jan 2018
- 2:38
- LEGO MINDSTORMS, LEGO MINDSTORMS EV3
- FIRST LEGO League, Motors, EV3, Gyro Sensor, Sensors, Physics, FLL, Programming
Experiment to find Compatible Motors
Take two of the motors and make the robot move forward ten times. Measure and record the difference. Then take another pair of the motors and repeat the above experiment. At the end, you should find the pair of motors that work best.
All the motors are compatible with each other, but by finding the once that are most compatible you will have the robot move in a straighter line.
English
When trying to move forward with the robot it might slightly move to the left or to the right. And this might be because of the motors. Although the motors look very similar they are not exactly similar and there are always some differences between the motors. So, you should try to find the best pair of motors that works for you. How do we do this? Let's discuss. When you buy the LEGO Mindstorms EV3 set it comes with 2 large motors and 1 medium motor. And that's fine for most of the cases but if you have additional motors probably because you won them in a competition or you've bought additional motors you should try to experiment with the motors. And to find the pair of motors that works best for your robot. Why? Because if you see on some of the videos that when the robot moves forward, it could make a slight mistake and turn to the left or turn to the right. And you can then just switch the motors and switch the ports and you'll see that the reverse will happen. So, it is not a problem of the construction, it's not a problem of the program it is sometimes just a problem of the motors because the motors are not perfectly similar and equal. There are some differences and the PID algorithm is trying to keep the robot moving in a straight line but there are some differences. So, the way you experiment: First, you take the robot and you move forward with the robot like 10 times and you record the different values of what is the error at the end. Then you change one of the motors for example, this motor here with another motor for example, this motor you change it and you test again. Move forward and record. Then you take the one that you have, put it on the other side and you do all kinds of combinations with the motors and at the end you have the recordings for each pair of motors and how the pair behaves and how precise the robot is at the end. And this is how you find the best pair of motors and you should try to use this pair from now on for this specific robot.
Courses and lessons with this Tutorial
This Tutorial is used in the following courses and lessons
Moving Straight with LEGO Mindstorms EV3 robots
One of the most controversial topics when it comes to LEGO Mindstorms robots is how to make them move in a straight line. This is a problem that has caused a lot of confusion among teachers, parents, rookie teams and students. The robot makes about 2-3 centimetres error for every meter, which is about an inch for every 3-4 feets. In this course, I would like to discuss the different ways in which you can improve the behaviour of the robot and how you could make it move in a straight line with the help of the LEGO Mindstorms EV3 Gyro Sensor.
- 24
- 102:09
- 3
Understanding the issues with moving straight
The balance of the construction of the robot has a great influence on how it will move. This is especially true if you would like to move in a straight line. If the robot is slightly heavier on the right it will move to the right. Here we have two robots - a Five Minute robot and a Box Robot and we will discuss the differences in the constructions and why the box robot is much better than the Five Minute even though it is using the same parts.
- 6
- 0
- 0
- 3d_rotation 2