A tendon-driven hand moves its fingers with cables pulled by motors placed in the forearm — the design that gives robot hands slim, light, human-like fingers, at the cost of tricky cable control.
A tendon-driven hand works like your own: the "muscles" (motors) sit back in the forearm and pull cables that run to the fingers, like tendons. This keeps the fingers slim and light while the bulky motors stay out of the way.
🎯 Quick challenge
In a tendon-driven hand, the motors are typically located…
Your fingers have almost no muscle in them — the muscles are in your forearm, pulling tendons. Robot hands that want human-like fingers copy exactly that arrangement: the tendon-driven hand.
How it works
Instead of putting a motor at every finger joint (bulky and heavy), a tendon-driven hand places its motors remotely — in the forearm or palm — and routes cables (tendons) through the fingers to the joints. Pulling a tendon flexes a joint; a spring or an opposing tendon extends it back. The fingers themselves stay slim and light because the mass is elsewhere.
Muscles back, fingers slim
Relocating the actuators off the fingers lets the hand be small and dexterous, like a human hand — the tendons transmit the force.
Why choose it
Slim, low-inertia fingers. Essential for a hand with many fingers and joints that must fit a human-scale form and move fast without heavy fingertips.
High degrees of freedom. It's the go-to design for highly dexterous hands (like the Shadow Hand) that need many independently controlled joints.
Compliance. Cables and their routing add natural give, useful for safe contact.
The challenges
Tendons bring their own headaches:
Friction and stretch. Cables rub in their routing and stretch under load, so the commanded and actual joint angles drift — precise control needs tension sensing and calibration.
Coupling. Routing tendons across multiple joints can make one joint's motion affect another.
Maintenance. Cables wear, fray, and need re-tensioning — a real reliability concern.
Simpler underactuated hands also use tendons but with few motors and passive springs, trading dexterity for robustness; fully tendon-driven dexterous hands maximize capability at the cost of complexity.
Where you'll see it
Research and humanoid dexterous hands, advanced prosthetics, and any robot hand aiming for human-like slimness and finger count — the platforms exploring fine manipulation and in-hand manipulation.
Why it matters
The tendon-driven hand is the enabling mechanism for human-like robotic hands — the reason a robot can have slender, agile fingers instead of fat motorized knuckles. It's central to the pursuit of dexterous, general-purpose manipulation.
