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Old Jul 18, 2016, 11:05 AM
Zari is offline
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Servo - Strong in one direction

Hi guys,

I am not experienced with servos so any ideas would be appreciated. Here is a problem I have:

with my flight controller (Arduino) I energise a servo but it is prevents rotation only in one direction.

Just to repeat - maybe It will explain my problem in a more clear way:
when I have servo on and I want to rotate it to the right (lets say) it does not allow me to do that. However, when I want to do that in the other direction, there is no resistance.

I am using servo HS-311.

Has anyone encountered such problem before?

Cheers !
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Old Jul 18, 2016, 12:18 PM
ScottSails is online now
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Quote:
Originally Posted by Zari View Post
Hi guys,

I am not experienced with servos so any ideas would be appreciated. Here is a problem I have:

with my flight controller (Arduino) I energise a servo but it is prevents rotation only in one direction.

Just to repeat - maybe It will explain my problem in a more clear way:
when I have servo on and I want to rotate it to the right (lets say) it does not allow me to do that. However, when I want to do that in the other direction, there is no resistance.

I am using servo HS-311.

Has anyone encountered such problem before?

Cheers !
Try a diff servo? What pulse width are you sending and how frequently?
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Old Jul 18, 2016, 01:45 PM
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I will second the above, what pulsewidth are you using and have you tried it with a different servo?
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Old Jul 18, 2016, 01:59 PM
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Quote:
Originally Posted by Zari View Post
Hi guys,

I am not experienced with servos so any ideas would be appreciated. Here is a problem I have:

with my flight controller (Arduino) I energise a servo but it is prevents rotation only in one direction.

Just to repeat - maybe It will explain my problem in a more clear way:
when I have servo on and I want to rotate it to the right (lets say) it does not allow me to do that. However, when I want to do that in the other direction, there is no resistance.

I am using servo HS-311.

Has anyone encountered such problem before?

Cheers !
Your Arduino unit must provide a repeating positive pulse signal that ranges from 1.0 Milliseconds wide to 2.0 Milliseconds wide, with a "zero" voltage signal lasting around 20 milliseconds. One way to do that, is to output a logic "1" signal to the servo, then "Call" a fixed 1.0 millisecond delay. Then, call a second time delay varying from 0 to 1 millisecond, with that delay controlled by the Arduino analog input for example. After the second variable delay, output a logic "0" to the servo. Then, call a 20 ms delay, and loop back to the start and do it again, and again, and again.

I've made dozens of these things using the PicChip product line. And, all worked very well.

Do note that the PicChips that I used ran at 5.0 Volts DC, where the Arduinos operate at something like 3.3 Volts DC. That might, or might not be an issue with your servos, since they are designed to operate at 5 Volts DC, with the newer servos capable of operating at 6.6 Volts DC. If you are trying to operate your servo at 3.3 Volts DC, that could cause problems with the servo's operation.
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Old Jul 18, 2016, 08:31 PM
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I don't think he is saying that he is driving a servo with a radio or servo driver, but by hand!
If so, he has found that servos, especially those from an off-brand system are made poorly, and if forced to move physically, due to poor gear geometry, the gears will shift and lock when an attempt is made to rotate them in a certain direction.
Servos, regardless of make or quality, should never be rotated manually, the back pressure on the gears can cause some distortion and lead to poor resolution.
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