A robot needs a maximum of three moving axes to reach every point in space (here: A1, A2, A3).

The axes are called principle axes. The principle axes move the effector to the designated position. Turning the effector into the right alignment is conducted by the hand axes.

For the orientation in space of the effector there are two to three hand axes necessary (here A4, A5, A6).

Depending on the arrangement of the hand axes, there is the central hand, angular hand and double angular hand.

The hand axes of robots are always R-axes. They turn the effector into the right orientation and alignment.