# 90-degree turn with LEGO Mindstorms robot ProPreview

The 90-degree turn of the robot is different from 90-degree turn of the motor!

• #422
• 26 Apr 2017
• 3:02

### 90-degree turn of the motor

Ninety degrees are a quarter of a rotation of the wheel. During a pivot turn, only one motor is turning. A quarter of a rotation is a very short distance and the result is that the robot moves only a little.

### 90-degrees turn of the robot

The expected result of a 90-degree turn of a robot is that the robot spatially turns 90 degrees to the side. That turn is very different from the quarter-turn of the motor.

### English

Now that we know how to use rotations and we also know how to use seconds and degrees, it's important to discuss what's 90 degrees. If I return to one of our previous programs for pivot turn, let me just start it so that you can see it on the camera. We move forward and as you see we are not turning to exactly right. We are turning slightly to the right but we must turn forward more. So, we must turn the whole robot to 90 degrees. And that's the subject of this video. In the software I'll create a new project

I'll zoom this project

and it's simple we need to make the robot turn to 90 degrees - turn right. So, I'll just take the large block

like this Here I'll click on degrees and here I'll set 90 degrees. And it's obvious. This should make the robot turn to 90 degrees with motor B. Let's download and see the result of this program.

Remember we programmed the block to turn the robot to 90 degrees and if I start the program, this will be the result of the program.

The robot is not turning to 90 degrees exactly to the right. Why? And that's a very common mistake in most of the classes and like 80 or 90% of all the students are doing this mistake. The reason is that we've programmed the wheel to turn to 90 degrees like this. And the wheel turning to 90 degrees does not mean that the whole robot will turn to 90 degrees. It's just the wheel turning to 90 degrees. Again.

So, turning the wheel to 90 degrees does not mean turning the whole robot to 90 degrees. What we must do is turn the wheel to 100, 200, 300 degrees. I don't know the correct value and this will make the whole robot turn to 90 degrees.

## Courses and lessons with this Tutorial

This Tutorial is used in the following courses and lessons

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