Degrees of Freedom (DoF)

The number of independent variables needed to fully describe a system's configuration — often a robot's independently movable joints.

Degrees of freedom (DoF) is the number of independent parameters needed to fully pin down a mechanical system's configuration. A free rigid body in space has 6 degrees of freedom: translation along x, y, and z, plus rotation about each of those three axes. Each rotary or linear joint on a robot typically contributes 1 degree of freedom, which is why people talk about a “six-axis arm” or a “7-DoF arm.” Six degrees of freedom is the minimum needed to place an end effector at any position and orientation in space; any joints beyond that are called redundant degrees of freedom, since the same end-effector pose can then be reached by infinitely many joint configurations — useful for avoiding obstacles. A human arm — 3 in the shoulder, 1 in the elbow, 3 in the wrist — has 7 degrees of freedom. When manufacturers quote a robot's total DoF, they often fold in the dexterous hand's fingers, so it's worth checking exactly what's being counted before comparing numbers.

ExampleAccording to Unitree's website, the base G1 has 23 degrees of freedom in total (6 per leg, 5 per arm, 1 in the waist); the EDU version, fitted with a dexterous hand and other add-ons, ranges from 23 to 43.

Also called

DOF

Related

Active DoF / Passive DoF · Kinematic Redundancy · Revolute Joint · Configuration Space (C-Space) · Joint Space · Underactuation

Sources

Wikipedia: Degrees of freedom (mechanics)
Unitree G1 官网规格 (Chinese)

As of

2026-09