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--- visual3d:documentation:modeling:segments:upper_arm_and_forearm [2024/07/03 17:39] – created sgranger
+++ visual3d:documentation:modeling:segments:upper_arm_and_forearm [2025/04/30 14:58] (current) – Cleaned up page. wikisysop
@@ Line 1: / Line 1: @@
-====== Upper_Arm_And_Forearm ======
+====== Upper Arm And Forearm ======
-==== Recommended Posture for the static trial ====
 Defining the segment coordinate system for the humerus is particularly difficult because there are no bony landmarks to assist in determining the glenohumeral joint center, and medial and lateral markers on the epicondyles are close together and often do not represent the axis of rotation of the elbow.
+===== Recommended Posture for the Static Trial =====
 **Note:: The following explanation is personal opinion and users should not accept this as a recommendation, rather as one plausible approach. Further work needs to be done in this area and users must decide for themselves.**
@@ Line 15: / Line 15: @@
   * The radius value for the proximal end of the upper arm is half the diameter of the upper arm at the level of the head of the humerus. The radius value for the distal end of the upper arm is half the diameter of the upper arm at the level of the elbow.
-==== I have created a thorax/ab segment and an upper arm segment, but no shoulder joint has been created. ====
+===== Common Difficulties =====
-Joints are a "book keeping" object in Visual3D because 6 degree of freedom segments don't have an anatomical joint. **//Joints//** are created to express the location at which the interaction torques and moments are applied between segments.
-In Visual3D, a **//Joint//** is created when the distal end of one segment is in proximity to the proximal end of another segment. In Visual3D, **proximity** is defined as the radius of the segment end.
+. I have created a thorax/ab segment and an upper arm segment, but no shoulder joint has been created.
-In order to have a shoulder joint created you must define the proximal end of the thorax/ab segment to be near the pelvis and the distal end near the shoulders. Typically, the distal end of the thorax is defined by markers placed on the acromium.
+Joints are a "book keeping" object in Visual3D because [[visual3d:documentation:kinematics_and_kinetics:six_degrees_of_freedom|6 degree of freedom]] segments don't have an anatomical joint. [[visual3d:documentation:kinematics_and_kinetics:joint|Joints]] are created to express the location at which the interaction torques and moments are applied between segments. In Visual3D, a **//Joint//** is created when the distal end of one segment is in proximity to the proximal end of another segment. In Visual3D, **proximity** is defined as the radius of the segment end. In order to have a shoulder joint created you must define the proximal end of the thorax/ab segment to be near the pelvis and the distal end near the shoulders. Typically, the distal end of the thorax is defined by markers placed on the acromium.
 **Note:** For the shoulder, this is sometimes still not sufficient to have shoulder "joints" created. If the distance from head of the humerus to the distal end of the thorax is more than the radius of the distal end of the torso, a joint won't be created. Moving the shoulder towards the midline slightly will often result in the shoulder joint be created.