Introduction to Internal Degrees of Freedom Part 1

by Stephen Braybrook.


Degrees of freedom refer to motion of a rigid body in three dimensional space time and distance. These are translation in three perpendicular axes concerning

  1. Moving up and down (heaving)
  2. Moving left and right (swaying)
  3. Moving forward and backward (surging)

Combined with rotation about three perpendicular axes

  1. Tilting forward and backward (pitching)
  2. Turning left and right (yawing)
  3. Tilting side to side (rolling)

With the movement along each of the three axes is independent of each other and independent of the rotation about any of this axis. It is important to remember that for a rigid body include also the velocity and angular velocity making it a 12-DOF system. As the human body contains 230 joints this make the total number of internal DOF (or in other terms the mobility of kinetic chain) available  2760 . The question is how does the human control so many DOF available?

Flight dynamics

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