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Topic: Rotating a servo with my hand, while it is powred. (Read 458 times) previous topic - next topic

Kumogakure

Hello, Is it possible to rotate a servo, with my hand, while it is powered? If it is, what should be the state of the controlling pin (pwm pin), Low, High, HZ?

Thanks, and sorry for the english =)

MarkT

They are not normally meant to be back-powered, you risk mechanically damaging the gearing.

Metal geared servos are more likely to survive such abuse.

While the servo is actively trying to hold position, forcing it out of position will cause large
currents to flow and rapid heating of the motor, typically causing overheating if you persist
for a while.

Different servos have different responses to a lack of control pulses, you'll have to experiment,
as normally they will hold position for a while (which is exactly what you want in an RC plane
if the radio control signal drops out for a short while).

What are you actually wanting to do?  A servo might be the wrong answer.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Kumogakure

Different servos have different responses to a lack of control pulses.
That might be the answer that I'm looking for...


What are you actually wanting to do?  A servo might be the wrong answer.
Well... I want to solder a wire in the internal potentiometer in order to get the position feedback, wich I will read using an analog input. With that, I intend to build a robotic arm that can learn movements with me moving it with my hands...

Something like this (1st video):
https://www.adafruit.com/product/1404

My doubt is: How did she manage to move the servo while it was powered? (you may have already answered this question) The servo that I'm willing to use is other (original MG996r and MG90S)...

I was looking for the answer so I could buy all the servos knowing that they would work as I wanted them to.

Thank you!

Kumogakure

I got the answers from the adafruit's forum: "The servo was powered, but the control pin was not putting out a signal. Most servos (including this one) will cut power to the motor if there is no pulse for 40 or 50 milliseconds or so".

TomGeorge

#4
Jul 26, 2016, 12:19 pm Last Edit: Jul 26, 2016, 12:20 pm by TomGeorge
Hi,

Read the product description.

Quote
ANALOG FEEDBACK SERVO
That is a special Analog Feedback Servo, designed to do what you are proposing.

A standard servo is not mechanically built to take that sort of punishment.

Tom.....   :)
Everything runs on smoke, let the smoke out, it stops running....

x_plus_y

Are you looking for something like this?

https://www.youtube.com/watch?v=s7aN-itWhFg

INTP

You may not understand the first part of the description,
"It looks like a servo, it acts like a servo, but it's more than just a servo!"

It is telling you that it is a special servo designed to do what it seems you want to do. Buy that servo.
Normal servos will not do what that one does.

Isaac96

All you need to do to make one of those servos is open it up and solder a wire to the center pin of the pot. That is a regular ser in the video, it was just modded with an extra wire. If you don't give the servo a signal, you can easily move it. Believe me, I use them for RC planes. 
Do not PM me for help. I will delete immediately.
CONNECT THE GROUNDS!

After Tuesday, even the calendar goes W T F

TomGeorge

#8
Jul 31, 2016, 03:10 am Last Edit: Jul 31, 2016, 03:12 am by TomGeorge
Hi,
All you need to do to make one of those servos is open it up and solder a wire to the center pin of the pot. That is a regular ser in the video, it was just modded with an extra wire. If you don't give the servo a signal, you can easily move it. Believe me, I use them for RC planes.
If you are referring to the video that the OP referenced, it is a special servo mechanically designed to be used that way.

Because of the high gearing used in servos to give them the strength and precision, forcing them to turn by applying mechanical pressure to the output shaft, will eventually result in gearbox failure and or motor damage.
Tom.... :)
Everything runs on smoke, let the smoke out, it stops running....

Isaac96

Actually, if you aren't giving it a signal, rotating it by hand will NOT damage it. I do it a lot and all my servos still work.
Do not PM me for help. I will delete immediately.
CONNECT THE GROUNDS!

After Tuesday, even the calendar goes W T F

JCOM

Actually, if you aren't giving it a signal, rotating it by hand will NOT damage it. I do it a lot and all my servos still work.

agreed now arduino setup I have a similar project, compare R/C -arduino mega 2560 2x, Arduino Pro Mini 328 - 5V/16MHz 2x, android cell and win10/win-phone BLU win8.1, the PS3 controller is a first try thing still getting documentation.


https://disqus.com/home/channel/rcarduino/discussion/channel-rcarduino/rc_resources/
come see my new project mercy https://disqus.com/home/channel/rcarduino/discussion/channel-rcarduino/rc_resources/
cheers to the innovations

TomGeorge

Everything runs on smoke, let the smoke out, it stops running....

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