I want to get one EV3 large motor to copy the other. So if I move one half a rotation the other copies.

  • 2
    Hi Nixtoo, can you share what programming language you're using and what you've already tried? It will help to get better answers.
    – MindS1
    Feb 24 '19 at 20:33

I am assuming that you want motor a to copy motor d and motor to is controlled manually(with your hands).

You can use the motor sensor to sense the degree of movements of motor d, then use link it to how much motor a turns. However, as motor d will still retain the degree it has been turn, motor a will continue moving even after motor d has stopped(unless you turn back motor d). To counter this, you have to use the switch block and a bunch of compare blocks. You will have to make it so that if motor a's degree is the same or more than b's degree, the motor degree will reset. However, if I turn d counter clockwise, d's degree will be negative and the comparison(same or more than)will not work and it will keep spinning. Thus, I added another switch block that will compare motor a's degree and motor b's degree, this time resetting the motor's degree when it is a is equal to or smaller than d.

enter image description here

This way what ever rotation done to d will happen to a.

Hope this helps you!


I would make a my block (with turquoise-colored tab) and move motor A and B in that block. You can make two parameters for speed and revolutions.

EDIT: Now you can control that motor-couple by using that my block.

  • Hi Sadap! I have interpreted the question as if the first motor should be passively accepting any rotations, and the EV3 should play these rotations back on the second motor in real time. If Nixtoo sees this, they can decide whether this reflects their original intent or not and give appropriate feedback.
    – zovits
    Apr 15 '19 at 19:45

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