Subject:
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Re: articulation points?
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Newsgroups:
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lugnet.build.mecha
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Date:
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Wed, 20 Nov 2002 01:16:29 GMT
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Viewed:
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928 times
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thanks for taking the time to answer my question. if i calculated correctly
(assuming that i count each joint only once per semetrical side , i.e., one
shoulder joint, one hip joint, etc.) my model has about 20 poa and 40 dof.
this is how i figure it: i used a ball joint for the head (3 poa),
shoulders (3 poa), hips (3 poa), waist (3poa) and feet (3 poa). i used hinge
joints for the elbows (1 poa) and knees (1 poa). i modeled the hands after
Gla-Gla's minifig arms idea, therefore there is 1 poa for the hinge of the
wrist as well as 1 poa for the rotation of that hinge. i also used friction
pins for the rotational joints of the arms independent of the shoulders (1
poa). if my math is correct, total poa is 20 and i assume that you double
the poa to find the dof. if my calculations are incorrect, let me know. i
should have some pics posted by december on brickshelf. thanks again.
In lugnet.build.mecha, Eric Sophie writes:
> Hello, I would define a POA as a point when mobility occurs whereas the
> rotattion is counted once. That is to say if a Shoulder joint spins forwards
> and back it counts as one POA and should not be counted as two.
>
> Example:
> In this picture of the Little Bot Foot:
> http://www.brickshelf.com/cgi-bin/gallery.cgi?i=174703
> The Ankle tilts forward and back
> The Ankle tilts side to side
> The entire foot spins at the upper ankle
>
> So that would be 3 points of articulation.
> Together the points combined create 6 degrees of freedom.
>
> As a rule of thumb I would say the POA should be counted then followed up by
> the total degrees of freedom.
>
> Example statement:
>
> My Mecha is kick arse! It has lot's of movement. It rocks! It has 12 POA
> giving the Mecha 24 DOF! Whoooo hooooo!
>
> This way we all know what we are talking about.
>
> Hope that helps. When we see your Mech we can see how many POA it has so we
> know the DOF.
>
> Good Luck!
>
> Legomaster
>
> In lugnet.build.mecha, Jason Coronado writes:
> > just wanted to ask some fellow mech-ers exactly what constitutes a point of
> > articulation. i am just finishing my second mech and i used at lease seven
> > ball joints for the shoulders, hips, waist, and feet. i also used plate
> > hinges in elbows and knees. how many p.o.a. is that?
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Message is in Reply To:
 | | Re: articulation points?
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| Hello, I would define a POA as a point when mobility occurs whereas the rotattion is counted once. That is to say if a Shoulder joint spins forwards and back it counts as one POA and should not be counted as two. Example: In this picture of the (...) (22 years ago, 19-Nov-02, to lugnet.build.mecha)
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