Six-Axis Force/Torque Sensor

A sensor that measures force along three axes and torque around three axes at once, often mounted on an arm's wrist.

A six-axis force/torque (F/T) sensor measures six quantities at once: the forces Fx, Fy, Fz along the x, y, and z axes, and the torques Tx, Ty, Tz around those same axes. A common design bonds strain gauges to a metal elastic body; the tiny deformation under load changes electrical resistance, which is converted through a Wheatstone bridge and calibration into the six components, though capacitive designs also exist. On a robot arm it usually sits between the wrist flange and the gripper, telling the controller how hard, and in which direction, the end-effector is being pushed or twisted — the basis for force control, impedance control, peg-in-hole assembly, sanding, kinesthetic teaching, and collision detection. Representative vendors include ATI and Robotiq, and in China, Sunrise Instruments and Kunwei Technology. Some arms skip this sensor entirely and instead estimate end-effector force indirectly from torque sensors on each joint.

ExampleThe Robotiq FT 300-S mounts between a collaborative arm's wrist and gripper, rated for ±300 N of force and ±30 N·m of torque, outputting data at 100 Hz, and is commonly used for peg-in-hole assembly and surface finishing.

Also called

F/T Sensor, Force/Torque Sensor, Multi-Axis Force Sensor

Related

Strain Gauge · Force Control · Impedance Control · Peg-in-Hole Insertion · Crosstalk (Inter-Axis Coupling) · Joint Torque Sensor

Sources

ATI Industrial Automation: Multi-Axis Force/Torque Sensors
Robotiq FT 300-S Force Torque Sensor
Wikipedia: Strain gauge