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Servos Neutral position

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Rookie ( offline )
Posts: 16
Posted: 2012-03-23 15:30 
 Post subject: Servos Neutral position
Hi all,

I discover after i have screwed the servos (HS-645MG) to the leg parts, that my legs doesn't have the same degree of freedom wich means that when i screwed the servo wheel on the leg bracket i didn't take care about the part position.

How could i know what is the neutral position of the leg to fix those screw. Is it the one shown on this picture ? (assuming i set the servos wheel with the 1 on the top as the neutral position)



Thx for your answer :)


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Guru ( offline )
Posts: 3298
Posted: 2012-03-24 00:57 
When you first buy servos they usually come with the servo horn set to the neutral position.
I usually check this by rotating the servo fully to the left or right and see if the holes rotate to 90° from centre.

If they are slightly out i pull the horn off and replace it so the holes are at 90° or represent the numbers 12, 3, 6, & 9 on a clock face. Then just rotate it back to centre leaving equal travel in both directions.

So assuming you have your servos set to neutral, but you need to mount it as pictured all you need to do is remove the horn and move it 45° or 3 notches of the servo shaft. One click = 15°. And then just push the horn back onto the shaft. This will mean the servo is still at neutral and/but the horn holes are offset to match the bracket.

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Jonny Poole,
Freelance Concept Art & Animatronics, 3D Art and 3D Modelling, as well as Physical Modelling, Mechanical design, and illustration.
http://www.innerbreed.co.uk
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Rookie ( offline )
Posts: 16
Posted: 2012-03-24 02:36 
Is the horn the white round wheel on the servo ? I should unscrew it and move clockwise at 45°, to fit the both condition, neutral and matched holes ?
Do i understood well ? :)


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Guru ( offline )
Posts: 3298
Posted: 2012-03-24 03:10 
Yes the white wheel is the servo horn.
And yes you will need to unscrew the horn that will require the 45° change to fit the condition of the holes on the bracket.
Be sure not to rotate the shaft when removing the screw.

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Jonny Poole,
Freelance Concept Art & Animatronics, 3D Art and 3D Modelling, as well as Physical Modelling, Mechanical design, and illustration.
http://www.innerbreed.co.uk
Create, Innovate, Inspire.


Rookie ( offline )
Posts: 16
Posted: 2012-03-24 03:26 
I set the neutral position like this:



And i have this degree of libertiy with my leg.



Is it normal that the end part of the leg can touche the middle part as shown on the picture ? Should i rotate the neutral position on the servo wheel a bit to avoid this contact ?




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Guru ( offline )
Posts: 3298
Posted: 2012-03-24 04:02 
Thats perfect. Thats its normal angle yes. Be sure to follow the tutorial as required.

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Jonny Poole,
Freelance Concept Art & Animatronics, 3D Art and 3D Modelling, as well as Physical Modelling, Mechanical design, and illustration.
http://www.innerbreed.co.uk
Create, Innovate, Inspire.


Rookie ( offline )
Posts: 16
Posted: 2012-03-24 04:05 
Thank you very much. it's very appreciated to have a such good support :D


Ps:Could you copy/past the link of the tutorial please, maybe i miss it.


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Guru ( offline )
Posts: 3298
Posted: 2012-03-24 04:20 
http://www.lynxmotion.com/images/html/build171.htm

_________________
Jonny Poole,
Freelance Concept Art & Animatronics, 3D Art and 3D Modelling, as well as Physical Modelling, Mechanical design, and illustration.
http://www.innerbreed.co.uk
Create, Innovate, Inspire.


Rookie ( offline )
Posts: 16
Posted: 2012-03-24 05:19 
ok thank you, i had this one :)


Rookie ( offline )
Posts: 16
Posted: 2012-03-24 06:24 
Is it ok for this servo too ? :)





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Guru ( offline )
Posts: 9258
Posted: 2012-03-26 09:52 
The range is not used in the calibration and set up of the legs! The position when commanded to 1.5mS is the only important part here...

http://www.lynxmotion.com/images/html/build171.htm

In steps 6,7,8,9 the servos are running and they are positioned at 1.5mS. Adjust them as instructed... So the axis points line up as illustrated... Then in steps 10,11,12 you move them the number of clicks as instructed. Please follow the tutorial and it will be a much easier process.

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Rookie ( offline )
Posts: 16
Posted: 2012-03-26 10:04 
Ok thank it will be the next step


 

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