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Author Topic: Do full rotation servos also stop at any of the degrees?  (Read 927 times)

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Offline EithmanTopic starter

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Do full rotation servos also stop at any of the degrees?
« on: November 30, 2012, 10:04:29 PM »
I have tried googling this for a while now and not found anything. I suspect its because I do not know the proper terminology. I just want to know if continuous rotation servos work the same as 180 degree servos in that they can go to any of the 360 degrees using PWM. Or do they only continually rotate in either direction (seems kind of pointless as regular motors do this) is there a special name for this type of full rotation servo or are they all like this? Any help would be really appreciated!

Offline Gertlex

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Re: Do full rotation servos also stop at any of the degrees?
« Reply #1 on: November 30, 2012, 11:41:19 PM »
Servos modified for full rotation lose position control.  If you read about how a hobby servo works, and what the modification entails, you'll understand why this is. 

The advantage over motors is that a $10 servo has control electronics/speed control (you don't need a separate h-bridge or motor driver), gear reduction, and an easy to mount to spline, all in a nice compact package.

There are the Dynamixel and Hovis lines of digital servos which can toggle between continuous rotation and position control.  These are more expensive ($35 for the cheapest Hovis servo, iirc).  The ~$200 Dynamixels have a ton of features, as well as 358 of position control.  These servos also do not use PWM, and can instead be daisy-chained, which is awesome.

I can't think of any specific terminology, though...
I

Offline waltr

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Re: Do full rotation servos also stop at any of the degrees?
« Reply #2 on: December 01, 2012, 11:14:04 AM »
To add:
The signal to a modified servo changes the rotational speed instead of its position.

Offline EithmanTopic starter

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Re: Do full rotation servos also stop at any of the degrees?
« Reply #3 on: December 01, 2012, 11:35:57 AM »
Thank you, that was very helpful!

 


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