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.

The whole course it two minutes - use or understand

The final program of the course is located in the final section. So, if you just need something that works without actually understanding how and why you can skip the next few sections, go to the last one, download the block and try to use it. But I would have to warn you that you might not understand the program in this way. You should also feel free to skip the sections for introduction with the Gyro sensor if you think you understand the basics of how it works and move directly to the Proportional part.

LEGO Mindstorms PID

It is worth mentioning that compared to other robotics sets and other ways in which you could build robots, the LEGO Mindstorms are doing a pretty good job when it comes to moving straight. They do have in internal PID algorithm implemented for both motors, but this is not enough.

By the end of our course, we would have the same robot moves straight. It will again make some errors, but it would be much more precise than the default behaviour.

Two parts of moving straight

Keep the robot orientation straight by correcting the mistake from the Gyro Sensor
Return the robot to the desired line after it makes an error

The best thing about this course is that it discusses the two parts. Most resources about LEGO Mindstorms robots discuss only how to keep the orientation straight, but not how to return to the straight line if the robot makes a mistake.