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Topic: Servo Motor (Read 176 times) previous topic - next topic

omaryehya

Hello
I am designing a project where I will be controlling a robot for various tasks.
one of the main tasks is a continuous sweeping of metal objects using a metal sensor
the sensor will be mounted on a plastic arm that is approximately 40 cm long, and a spray paint will be mounted there as well.
I figured that I will need a high torque motor to hold the arm and continuously move it 180 degrees.
while researching, I found this motor, the MG996R servo
  https://servodatabase.com/servo/towerpro/mg996r

will it be strong enough to hold it?
if not what are your recommendations, and should I switch for a stepper motor instead?
the weight of the arm adding the sensor and spray paint should be around 2 kilograms.
Thank you

vinceherman

#1
Apr 12, 2019, 04:22 pm Last Edit: Apr 12, 2019, 04:23 pm by vinceherman
Hi omaryehya, welcome to the forum.

Your description of the arm is not clear. 
Does it simply sweep from side to side without any lifting?
Does the arm have bearings supporting the weight or you you expecting to attach it to the servo arm?

Any time you are dealing with larger weight and longer arms, you need proper weight bearing structure.
Look at servo city and other robot cites to see how they manage that.

If the servo simple needs to move the arm from side to side, and is not bearing the weight of the arm, then this might work.  It might not move it quickly.  You might have to build in an acceleration and deceleration portion on the start and stop of the swing.  Any you might try it out and see if you are overloading the servo and making it heat up.

Robin2

You need to provide a diagram of your proposed mechanism.

For a weight of 2kg I would like to have a proper load carrying bearing so that the servo is only causing the motion to happen and not carrying the weight on the servo bearing. (I am assuming the arm will be sweeping horizontally).

How do you propose to keep paint off the sensor?

What is the sensor?

What is the purpose of the project?

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

omaryehya

Hello
yes, the arm will only be moving horizontally to do the sweeping.
we will mount the sensor directly on the arm, while the spray paint will be fixed on a bearing structure next to the sensor, also on the arm.
I didn't understand by what you mean when you said ''servo is only causing the motion to happen and not carrying the weight on the servo bearing.''
shouldn't the servo also carry the weight if everything is mounted on the arm?

Unfortunately, I can't try it out right now, this is my senior design for university, and the first part is only a report of what parts we are using. So i can't know if it will cause the servo to overheat.

Robin2

#4
Apr 12, 2019, 05:52 pm Last Edit: Apr 12, 2019, 06:05 pm by Robin2
shouldn't the servo also carry the weight if everything is mounted on the arm?
If by "the arm" you mean the arm attached to the servo then I (and @vinceherman) am saying that you should NOT mount all that weight on it.

Make a completely separate arm to carry the load and connect the servo arm to the load-carrying arm with a push/pull rod.

Something like this, is what I have in mind



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

MarkT

You need to draw a diagram of the linkages/arm you are talking about to make things crystal clear...
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

omaryehya

Oh Ok
I get you now, yes this is a much better idea that what I originally had in mind.
I think this solved my problem. Thank you all very much for the assist

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