Hi Soeren, just five minutes ago I found the same soluten after I added up the

single distances between the local Ref and the absolute coordinates for CoM.

Thank you very much, now itÂ´s clearer and I now know what this Offset is. With

best regards, Maren

----- UrsprÃ¼ngliche Mail ----

Von: AnyBody Support <support@anybodytech.com>

An: anyscript@yahoogroups.com

Gesendet: Mittwoch, den 2. August 2006, 14:59:52 Uhr

Betreff: [anyscript] Re: Coordinates of CoM

```
Hi Maren
```

Your assumption of the expected position of Show_sCom to be

(0.01868401, 0.35346004, 0.1929215)

is only correct if the local cooridnate system of the humerus

segment is 100% alligned with the global ref system, if this is the

case then your are right. In the present case the orientation of

humerus segment is slightly out of allignment so a translation of -

0.061 along the local y axis of the segment will also produce a

small movememt in the global x and z coordinates because the axes

are not alligned. I think this is why you do not get the constant x

and z values you expected.

The Offset value has been used to translate the nodes of the segment

by a certain amount, i do not think it will have any influence here.

So to summarize:

sCom is given in the local coordinate system of the segment

You can find the r value of Com as the r vector of the Show_Com node

I hope this made it more clear, otherwise please do not hesitate to

write again.

Best regards

SÃ¸ren, AnyBody Support

— In anyscript@yahoogrou ps.com, “Maren” <anystarter@ …> wrote:

>

> Hi Soeren,

> I build a new model for the arm movement where I use the new files

you

> uploaded. Now I want to scale another model to the AnyBody size and

> therefore I look for exact coordinates again. Normally no problem

but

> in this model there are difficulties: for the humerus segment I

need

> the origin, the joint coordinates and the CoM coordinates. When I

> click through the window next to the texteditor I get the values

for

> the origin, but I donÂ´t find the definition of this origin. But

thatÂ´s

> not my problem. The joint coordinates were easy to find, after a

> kinematic analysis I got nice values.

>

> But now my question:

> The variable “sCoM” is defined in relative coordinates. When I

want to

> know the absolute coordinates I define a RefNode with the same

> coordinates like sCoM and after loading and running a kinematic

> analysis again I can click in the window next to the text editor to

> get “r”. I tried it for the Humerus segment but the absolute values

> for this sCoM node doesnÂ´t fit with the origin+relative

coordinates.

> I definied it like this:

>

> sCoM={0,-0.18* Length,0} ; //given by the model

> AnyRefNode show_sCOM= //defined by myself

> {

> sRel = {0,-0.18*.Length, 0};

> AnyDrawRefFrame sCOM=

> {

> RGB = {1,0,0}; //rot

> ScaleXYZ = {0.3, 0.3, 0.3};

> };

> };

>

> Here are the values I get for r, sCoM and abs. sCoM:

>

> Main.Model.HumanMod el.Right. ShoulderArm. Seg.Humerus. r =

{0.01868401,

> 0.4146685, 0.1929215};

>

> Main.Model.HumanMod el.Right. ShoulderArm. Seg.Humerus. sCoM = {0,

> -0.06120846, 0};

>

> In my opinion this has to give the absolute coordinates for sCoM:

> (0.01868401, 0.35346004, 0.1929215) > x and z were the same as

before!

>

> But AnyBody calculates:

> ain.Model.HumanMode l.Right.Shoulder Arm.Seg.Humerus. show_sCOM. r =

> {0.02399838, 0.353925, 0.1982561};

>

> Now IÂ´m confused. Where is r for the humerus segment defined? Which

> coordinate system is sCoM defined relative to? What does the

AnyVec3

> Offset mean? ( I uploaded the model named Armmodell04) Does this

> Offset influence the coordinates of sCoM? WhatÂ´s his job? How do I

> have to calculate if I want to know the absolute coordinates of the

> CoM? I hope you can solve my confusion.

>

> Thank you very much and with best regards, Maren

>

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