What is a force-torque sensor on a robot?
A force-torque (F/T) sensor, usually at the wrist, measures three forces and three torques so the robot can feel contact during assembly, polishing or safe interaction.
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Definition
A force-torque sensor measures the three linear forces and three moments (torques) acting on it — a full 6-axis contact wrench.
How it works
Mounted at the wrist, it tells the controller how hard the tool pushes and in which direction. Controllers use that for force-controlled insertion, polishing at constant pressure, hand-guiding and collision detection.
Why it matters
Cameras do not feel jam forces. Adding F/T is often the difference between a demo grasp and reliable assembly — and richer training data for contact-rich policies.
Frequently asked questions
Where is it mounted?
Typically between the last joint and the [end-effector](/{L}/glossary/end-effector).
Why not just use joint torque?
Wrist F/T gives a cleaner 6-axis contact wrench at the tool; joint sensors also work on many [cobots](/{L}/glossary/cobot) but resolve contact differently.
Role in learning?
F/T observations help [imitation learning](/{L}/glossary/imitation-learning) on contact-rich tasks that vision alone misses.
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