What is degrees of freedom in a robot hand?
Degrees of freedom (DOF) in a robot hand count the independent joint motions it can control. Active DOF are driven by motors; passive DOF move with the object. Compare hands on active DOF, not on the headline total.
Degrees of freedom (DOF) on a robot hand is the count of independent motions the hand can make. Each driven joint is one active DOF. Joints that are coupled to a driven joint — or that simply comply when the finger meets an object — are passive DOF.
This distinction is the whole point. A hand quoted at 22 DOF with 11 motors and a hand quoted at 11 DOF with 11 motors may be mechanically similar; only the second lets you command every motion independently. Passive DOF are not worthless — they are how a hand conforms to an object without extra actuators, cost and control effort — but they are not something your controller can place.
How to compare two hands
- Active DOF first — what your policy or planner can actually command.
- Then the coupling scheme — which joints move together, and whether that matches your grasps.
- Then payload and mass — DOF is meaningless if the wrist cannot carry the hand or the hand cannot hold the part.
- Then sensing — tactile arrays and force feedback decide whether closing on an unknown object is controlled or blind.
Range by active DOF is laid out in dexterous hands; if teleoperation or demonstration capture is part of the plan, evaluate a motion capture glove in the same window.
FAQ
How many DOF does a humanoid hand actually need?
For most platform work, six to eleven active DOF covers power grasps, pinch and basic in-hand adjustment. Above that you are buying manipulation research capability, and you need a control stack and a data pipeline that can use it.
Do passive DOF count toward dexterity?
They count toward adaptability, not controllability. A passive joint lets a finger wrap an object instead of pinching it, which widens the set of shapes you can hold, but you cannot command its position.