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Topic: Motor solution. (Read 1 time) previous topic - next topic


Hi, as you can see in the picture (red arrow pointing), i'm using 2 servo motor to control the arm to move "up" and "down". Without holding anything the arm is perform nicely (use only 1 servo motor); But when I hold something like a TV remote control or cellphone, it barely able to raise (even run with 2 servo), and the servo motor will keep "vibrating" until the arm fall down and repeat the "raise>shake>fall" step.

The servo motor that i using is TowerPro MG996R metal gear servo motor operating by arduino 5V output, using a potentiometer to control the direction of the servo gear.

Does anyone know what's happen? Is it the servo motor not enough strong power to raise a remote control? The servo motor is a 10kg torque, should I change it into 15kg torque so that it can raise up easily?


I suspect the Arduino 5v output can't supply enough current for your servo when it is under load. Also, drawing too much current might damage the Arduino.

Normally you should power servos from their own power supply with the ground shared with the Arduino.

Two or three hours spent thinking and reading documentation solves most programming problems.


Certainly a big servo like that cannot perform on an inadequate power supply - fix this first.

But secondly you have given it a large torque load to handle - your robot arm would be far far easier
to drive if each section was counter-balanced (even partially).  The current setup needs a lot of torque
just to raise the arm, let alone any load.

The servo motor is a 10kg torque, should I change it into 15kg torque so that it can raise up easily?

kg is not a unit of torque.  I suspect you mean 10kgf-cm or some such unit - without knowing for sure I can't
tell if the change would be useful.  You should always try to work in S.I. units for torque, its so much more
convenient and simple.

You need to work out the torque needed to drive the arm comfortably (a rough estimate in N-m is
10 x M x L, where M is the total mass of the moving arm in kg and L is the length in m.)

For instance a 0.4m long arm weghing 0.5kg would work well from a 2N-m servo.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]


Typical way to power servos:

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