EV3 Phi. Difference between Rotations and Seconds for a move block Pro Preview

Why we will never use seconds in our lessons.

  • #420
  • 24 Apr 2017
  • 3:55

The power will define the distance

A distance traveled in 3 seconds with a power of 10% is shorter than a movement for 3 seconds with power on 90%.

On the other hand, 3 rotations (or 300 degrees) will always move the robot the same distance, no matter what power we set for the movement.

Influence of the battery

And because power defines the distance when using seconds, we will lose precision with the discharge of the battery. That is why you will not see us program movements with Seconds, because they are usually inaccurate.


When programming the robot you can set the motor to move for a number of seconds, for a number of rotations or for a number of degrees. And in this video it's a good opportunity to discuss when to use seconds, when to use rotations and when to use degrees. Let's start with a simple example.

I'll just take one move steering block for moving forward. And I'll set this block to move with a power of 10 for 1 rotation. So, we are using rotation. This will make the robot move forward with a power of 10 for 1 rotation until the whole wheel does 1 rotation. Download.

The robot moves forward with a power of 10 and the wheel makes a whole rotation. What if we set just seconds not rotations. I'll do a similar program. First, I'll call this program not 'turn' but 'rot' from rotations then I'll create a new program and in this new program

I'll take a steering block. Set the power to 10 and configure the robot to move forward for 1 second. So, it's very similar. You see rotations it's 0 - 10 - 1 as configurations of the block and here for seconds let's call this seconds it's 0 - 10 - 1 again but we've set the robot to move forward for 1 second. Download the whole project and let's see the difference between the two programs. In the menu of the brick I have the two programs - sec and rot. Sec from seconds and rot from rotations. And if I start the program for 1 second,

this is how far the robot gets. It moves 1 second with a power of 10. But if I now start the program for rotations,

the robot will move forward until the wheel does a whole rotation. Again.

What's important is that with the power we set how fast we want to move with the robot and with seconds and rotations we set the duration. Because power defines the distance when using seconds we'd lose the precision with the discharge of the battery. That's just one of the examples. It is most of the time advisable to always use rotations because if you use seconds, the robot will move more inaccurately. And that's the difference that you must remember. When using seconds the robot would be not that accurate compared to when using rotations and degrees.

Courses and lessons with this Tutorial

This Tutorial is used in the following courses and lessons

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