Update Joint.py

The former script seams to be brocken due to an API change.
It seams that the origin of the components is not set correct in the URDF File. The origin needs to be set to the joint values, because the STL files are in the context of the main construction.
I found the calculation for the xyz values in the Autodesk Forum:
https://forums.autodesk.com/t5/fusion-360-api-and-scripts/difference-of-geometryororiginone-and-geometryororiginonetwo/m-p/9837767

Hope this fix the issue

URDF_Exporter/core/Joint.py

@@ -175,9 +175,47 @@ def make_joints_dict(root, msg):
             joint_dict['parent'] = re.sub('[ :()]', '_', joint.occurrenceTwo.name)
         joint_dict['child'] = re.sub('[ :()]', '_', joint.occurrenceOne.name)
 
+
+        #There seem to be a problem with geometryOrOriginTwo. To calcualte the correct orogin of the generated stl files following approach was used.
+        #https://forums.autodesk.com/t5/fusion-360-api-and-scripts/difference-of-geometryororiginone-and-geometryororiginonetwo/m-p/9837767
+        #Thanks to Masaki Yamamoto!
+
+        # Coordinate transformation by matrix
+        # M: 4x4 transformation matrix
+        # a: 3D vector
+        def trans(M, a):
+            ex = [M[0],M[4],M[8]]
+            ey = [M[1],M[5],M[9]]
+            ez = [M[2],M[6],M[10]]
+            oo = [M[3],M[7],M[11]]
+            b = [0, 0, 0]
+            for i in range(3):
+                b[i] = a[0]*ex[i]+a[1]*ey[i]+a[2]*ez[i]+oo[i]
+            return(b)
+
+
+        # Returns True if two arrays are element-wise equal within a tolerance
+        def allclose(v1, v2, tol=1e-6):
+            return( max([abs(a-b) for a,b in zip(v1, v2)]) < tol )
+
         try:
-            joint_dict['xyz'] = [round(i / 100.0, 6) for i in \
-            joint.geometryOrOriginOne.origin.asArray()]  # converted to meter
+            xyz_from_one_to_joint = joint.geometryOrOriginOne.origin.asArray() # Relative Joint pos
+            xyz_from_two_to_joint = joint.geometryOrOriginTwo.origin.asArray() # Relative Joint pos
+            xyz_of_one            = joint.occurrenceOne.transform.translation.asArray() # Link origin
+            xyz_of_two            = joint.occurrenceTwo.transform.translation.asArray() # Link origin
+            M_two = joint.occurrenceTwo.transform.asArray() # Matrix as a 16 element array.
+
+        # Compose joint position
+            case1 = allclose(xyz_from_two_to_joint, xyz_from_one_to_joint)
+            case2 = allclose(xyz_from_two_to_joint, xyz_of_one)
+            if case1 or case2:
+                xyz_of_joint = xyz_from_two_to_joint
+            else:
+                xyz_of_joint = trans(M_two, xyz_from_two_to_joint)
+
+
+            joint_dict['xyz'] = [round(i / 100.0, 6) for i in xyz_of_joint]  # converted to meter
+
         except:
             try:
                 if type(joint.geometryOrOriginTwo)==adsk.fusion.JointOrigin:
@@ -190,4 +228,4 @@ def make_joints_dict(root, msg):
                 break
 
         joints_dict[joint.name] = joint_dict
-    return joints_dict, msg
+    return joints_dict, msg