Navigating 5DOF(Degrees of Freedom) and 6DOF Sensors

The degrees of freedom (DOF) describes the number of axes in which a rigid body (object) moves freely in 3D space.

Degrees of freedom are reported as translations and rotations.

Translations (positions) on the X, Y, and Z-axes correspond with the following motion:

Moving forward/back on the X-axis (surge).
Moving left/right on the Y-axis (heave).
Moving up/down on the Z-axis (sway).
Rotation on these axes provides orientation data:

Tilting side-to-side on the longitudinal/X- axis (roll).
Tilting forward/back on the transverse/Y-axis (pitch).
Turning left/right on the normal/Z-axis (yaw).

With 5DOF sensors, all three translations, and two of the three rotations are reported. Roll is excluded. Tracking in 5DOF could be based on movement limitations of the object, i.e., the object cannot physically turn (roll) side-to-side. Or it could be based on the object’s configuration and how it’s manually manipulated, such that its roll information does not need to be reported. For example, tracking the roll rotation of a needle is less important than knowing the position of the needle’s tip and the direction of where the tip is pointing. The roll orientation data is unnecessary.

With 6DOF sensors, all three translations and rotations are reported on the X-Y-Z axes. This means the ridged body, object, or system can move or rotate independently along all six possible axes in a 3D space. (It also means reporting an object’s roll movement is necessary during the navigated procedure.) This level of freedom allows for more complex movements and orientations to be tracked when navigating inside the body. Another example would be that a robotic arm with 6DOF can reach a wider range of positions and orientations compared to a system with fewer degrees of freedom.