I have a question regarding "AnyStdJoint". Since this is the
base class for all standard joints and creatable, my question is…
Is it possible to make “AnyStdJoint” work like a Revolute Joint or
Prismatic Joint by adding certain constraints or reaction forces. If
so, my next question is
Can I make this joint created from “AnyStdJoint” move according to
some 3D data (x,y,z) stored in a file sing “AnyKinEqInterPolDriver”?
Any suggestions or solutions to these questions would be very
helpful. I thank in advance to all those who tried or even given a
thought about these questions.
The first few times a user posts to the group, the post has to be
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AnyScript has a predefined class hierarchy just like JavaScript. This
means that users cannot define their own classes but can only specify
instances of existing classes. So you cannot derive a revolute joint
from a standard joint.
But there is a whole lot of stuff you can do. A joint controls
kinematics and also provides the reaction forces to enforce the
kinematics. But you can switch these reaction forces off, and this
can also be done in a standard joint. This means that the joint will
still specify the kiematics, but the necessary reactions must come
from somewhere else.
For instance, if you have a physiological joint that uses ligaments
to provide joint stability and you want to find the forces in the
ligaments, then you can switch the reaction force(s) in the joint off
and define some other structure more similar to a ligament to provide
the resactions. This will typically be an AnyKinLinear or an
AnyKinPLine.
You can also build your own joint bottom-up by means of various
kinematic measures. This will give you complete freedom in defining
the joint you like.
If you describe the problem you have in more detail, then I can
probably give you a suggestion on how to model it.
Best regards,
John
— In anyscript@yahoogroups.com, “rokual” <ksk5@b…> wrote:
>
>
> Hi group,
>
> I have a question regarding “AnyStdJoint”. Since this is the
> base class for all standard joints and creatable, my question is…
>
> Is it possible to make “AnyStdJoint” work like a Revolute Joint or
> Prismatic Joint by adding certain constraints or reaction forces.
If
> so, my next question is
>
> Can I make this joint created from “AnyStdJoint” move according to
> some 3D data (x,y,z) stored in a file
sing “AnyKinEqInterPolDriver”?
>
> Any suggestions or solutions to these questions would be very
> helpful. I thank in advance to all those who tried or even given a
> thought about these questions.
>
> Regards,
> Kiran
Yahoo filters off attached files before the message gets posted, but
I have uploaded your picture to the files section. This is the best
way to convey pictures and AnyScript models etc. to the group.
> 1. Is it possible to drive the tip of ‘T’ using the data in a file?
Sure it is. You need to define an AnyKinLinear between the tooth tip
and the origin of your coordinate system. Subsequently, simply define
two interpolation drivers and let them drive the two coordinates of
the measure.
But please notice that because of the revolute joint you only have
one degree of freedom between segments A and B in the present model,
so you need to allow for one additional degree fo freedom before you
can drive two coordinates. One way to do this could be to divide
segment A into two parts with a prismatic joint between them.
> 2. Can I attach an “AnyStdJoint” instead of revolute joint and make
it
> behave like an revolute joint to suffice my needs?
No, the correct method is to introduce another degree of freedom as
mentioned above. In the long run, though, you should consider how the
real tempora-mandibular joint provides two or more degrees of
freedom. I believe this is by means of a combination of rotation and
sliding. So perhaps the joint has to be placed on an aditional
segment which is then attached to the cranium by means of a prismatic
joint.