my servo motor wont hold moment when off

hi
we built a robotic arm in class project and we notice that the servo motor wont hold the arm connected to it when we not connecting the power supply but when we do connect it to the power supply the motor holding it very well and its working fine
how do we force the arm to stay in place when the power is off ?

i am new here so i hope i follow the guidelines :slight_smile:

Servo motors tend to lose their position when powered off, and can go to arbitrary positions when power is applied again. If you need a position keeping actuator, use a DC motor with a self-locking gear box, and an encoder for position feedback.

jon1989:
hi
we built a robotic arm in class project and we notice that the servo motor wont hold the arm connected to it when we not connecting the power supply but when we do connect it to the power supply the motor holding it very well and its working fine
how do we force the arm to stay in place when the power is off ?

You can't. That's not how servos work. They are basically geared motors with control electronics. If you switch off the power the Arduino is no longer telling it what its position should be, the electronics can't tell the motor what to do to get there and anyway the motor has no power to get it to the correct position. Any load on the servo arm will cause it to move.

Steve

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There are servo motors that lock, used in industrial robots, when powered off, you can use one of those servos.

Also, you can use a solenoid attached to the device in some fashion. A kind of solenoid that when powered on will pull the rod back and when powered off the rod inserts its self for braking.