What Does Six Degrees of Freedom Mean?
Six degrees of freedom (6DOF) refers to the specific number of axes that a rigid body is able to freely move in three-dimensional space. It defines the number of independent parameters that define the configuration of a mechanical system. Specifically, the body can move in three dimensions, on the X, Y and Z axes, as well as change orientation between those axes though rotation usually called pitch, yaw and roll.
Techopedia Explains Six Degrees of Freedom
Six degrees of freedom is a specific parameter count for the number of degrees of freedom an object has in three-dimensional space, such as the real world. It means that there are six parameters or ways that the body can move.
Six degrees of freedom consists of the following movement parameters:
- Translation – Moving along the different axes X, Y and Z
- Moving up and down along the Y axis is called heaving.
- Moving forwards and backwards along the X axis is called surging.
- Moving left and right along the Z axis is called swaying.
- Rotation – Turning in order to face a different axis
- Moving between X and Y is called pitch.
- Moving between X and Z is called yaw.
- Moving between Z and Y is called roll.
A very good example of an object that has 6DOF is an airplane. It can move freely in three-dimensional space, with the two horizontal axes as X and Z while the vertical axis is Y. If it needs to face up or down, it needs to change the orientation of its nose from horizontal X to Y, which is called pitch. If the plane needs to turn from the X axis to the Z axis without changing the orientation of its body, it can do a yaw by using its rudder so the wings remain horizontal while the nose starts to point to the Z axis. Finally, since it is often assumed that the X orientation is always where the nose is facing with regards to the plane, moving the plane from X to Y will make it roll, hence the term. The pilot can then combine any of these parameters of movement to execute maneuvers.
This concept is often used in engineering and robotics. Most game console controllers sense 6DOF input from the controller’s thumb stick, and this is the same for many remote-controlled toys. Cell phones have 6DOF sensors that track the movement of the phone. In robotics, robots can have more than six degrees of freedom, as the individual modules can be considered separate and aggregate at the same time, meaning that each segment’s DOF contributes to the whole. So a robotic arm with three segments and each jointed segment having six degrees of freedom, it can be said that the robot arm has 18 degrees of freedom.