Joint Kinematics
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Body segments are linked to each other at the joints. The joint structure determines the types of joint motions allowed at the joint. Joint motion is actually the relative motion of the distal segment to the proximal that together form a joint. Analytically speaking, it is advantageous to view joint motions as the relative motions between the rigid bodies. This section will deal with issues related to the joints and the relative motions between the articulating segments.

One of the key concepts in this section is the orientation angles that visualizes the relative orientation of the distal segment to its linked proximal segment. The following pages deal with the issues related to the orientation angles:

Orientation Angles
Computation of the Orientation Angles
Angular Velocity vs. Orientation Angles
Joint Angle vs. Orientation Angles
Electromagnetic Motion Sensors

Another important issue in the joint kinematics is the location of the joint center (center of rotation) and the axis of rotation. For example, accurate determination of the location of the joint center is the bottom line in the joint kinematics while the location and migration of the axis of rotation has bearings on the computation of the moment arms of the muscles. Empirical methods are also available but the following pages specifically deal with selected numerical methods of determining the joint center and the axis of rotation:

Joint Center: Functional Method
Computation of the Rotation Matrix
Singular Value Decomposition (SVD)
Helical (Screw) Axis
Motion Sensors: Joint Center


Young-Hoo Kwon, 1998-