Degrees of freedom (DOF)

The number of independent motion variables a mechanism has, which for serial robot arms usually equals the number of actuated joints. Positioning and orienting a tool arbitrarily in space requires 6 degrees of freedom; a 7-axis arm is kinematically redundant, letting it reach the same tool pose with different elbow positions to avoid obstacles. Legged and humanoid platforms carry far higher joint counts because each limb contributes several actuated axes.

Standard
ISO 8373, International Organization for Standardization (2021)