Planetary gear motor

Help & Support Robot Parts
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1

Hi,

I need 6 motors in order to move my 50Kg robot, i find that i need 200 Kg.cm.
So, i choose to use this planetary gear motor from gobilda (5203-2402-0188).
But i can’t find motor like this one with brake.

Do you know where i can find little motors with 200Kg.cm torque and with a brake ?
If, i use the gobilda motors (5203-2402-0188), did my robot goes backwards on the slope ?

If you have some ideas don’t hesitate :wink:

Sorry for my bad english by the way :slight_smile:

2

Can i take out the encoder and replace it by brake ?

3

Hello @Nayeon49!

Unfortunately, we don’t have any similar motors with brakes and it is not possible to replace the encoder with a brake.

I suggest asking the manufacturer if they have compatible brakes:
https://www.gobilda.com/support/

Do you already have the motor controller you are going to use? If not a good option could be the Sabertooth 2x32:

Which allows you to control electromagnetic brakes, these can be connected to the Sabertooth’s 2x32 auxiliary 8Amps outputs as explained in the Sabertooth’s user manual page 9 and page 14

If, i use the gobilda motors (5203-2402-0188), will my robot go backward on the slope?

If the motors can provide enough torque to climb up the slope without stalling then the robot shouldn’t go backward. In case you haven’t checked it out here’s a great tool for calculating the torque needed:

4

Ok thank you for your answer.

In fact, i need to put emergency button on the robot, so i’m afraid. Because if i need to use emergency button on the slope the robot might go backward. That’s why i need brakes.

5

In fact, i need to put emergency button on the robot, so i’m afraid. Because if i need to use emergency button on the slope the robot might go backward. That’s why i need brakes.

Oh I see. Although, as the motors you mentioned have such a high gear ratio you might still be able to lock your robot in place and prevent backdrive even on a slope (depending on the incline).

You have a couple of options:

  • Sending a zero power command which will cause the motor’s back EMF to fight the rotation.
  • Using the encoders you could set the velocity to zero. This way you will be using feedback to try keeping the velocity equal to zero.
  • Use position feedback to command a specific position and use a PID loop to stay in the same position.

However, adding an actual mechanical brake would be the most reliable solution.