local orientation of the Ankle joint

Main Forum
1

Hi,

Last period I have adjusted the ankle joint in a spherical joint. But I have doubts about the axis framework in the model. In the revolute joint the euler orientation is ZYX but I do not know how this is the case in a spherical joint. Where can I check this and how can I change this orientation?

Best regards,

Hans

2

Hi Hans,

The spherical joint by default has the Orientation.Type =rotvector, this can be changed it also has by default Orientation.axis1=Z, Orientation.axis2=Y, Orientation.axis3=x this can also be changed.

Please have a look in the manual for details.

Best regards
Søren

3

Hi,

Thank you for your reply. But I still have another question. How could I check the direction of each axis in the Ankle joint?

Best regards,

Hans

4

Hi Hans,

If you want to visualize the joint axis, this can be done by adding an AnyDrawRefFrame to the node use by the joint, please see example below.

Best regards
Søren


AnyRevoluteJoint Ankle = {
  Axis = z; //flexion extension
  //Axis2  =  x; //abduction adduction
ShankNode ={AnyDrawRefFrame drw={RGB={0,0,1};};};
  AnyRefNode &ShankNode = ..Seg.Shank.AnkleJoint;
  AnyRefNode &FootNode  = ..Seg.Talus.AnkleJoint;
   //ShankNode ={AnyDrawRefFrame drw={RGB={0,1,0};};};
};

AnyRevoluteJoint SubTalar = {
  //Axis1 = z; //flexion extension
  Axis =  z; //inversion eversion 
TalusNode ={AnyDrawRefFrame drw={RGB={0,0,1};};};
  AnyRefNode &TalusNode = ..Seg.Talus.SubTalarJoint;
  AnyRefNode &FootNode  = ..Seg.Foot.SubTalarJoint;
  //TalusNode ={AnyDrawRefFrame drw={RGB={1,0,0};};};

};
5

Hi,

Thank you for your reply. Is this also appliciable for the spherical joint?

Best regards,

Hans

6

Hi Hans,

Yes this can be done for any joint.

I have just added a visual references system to the first mentioned node in the
joint.

Best regards
Søren

7

Hi,

I have made the reference frames vissible in the ankle joint. Is there a possibility to change the direction of the individual axis in AnyBody?

Best regards,

Hans

8

Hi Hans

This is this possible yes.

To do this you simply need to modify the ARel property of the nodes being used for the joints.

So by writing for example

ARel= CURRENTVALUERotmat(10pi/180,z);

It would rotate the axis 10 deg around z axis of the reference frame of the parent node, in most cases this would be the segment coordinate system.

Best regards
Søren