Hardware & control
Force–torque sensing
Force–torque sensing is the measurement of forces and rotational moments transmitted through a robot interface, commonly with a six-axis sensor reporting three force components and three torque components. The combined quantity is a wrench expressed at a specified origin and in a specified coordinate frame. It measures the resultant load at the sensor, not a spatial pressure map across every contact.
Also known as: force-torque sensing, force/torque sensing, F/T sensing, force-torque sensor, force/torque sensor, F/T sensor, wrench sensing
Updated
A six-axis sensor reports one resultant wrench
Modern Robotics packages three-dimensional force and moment into a six-component wrench. Commercial six-axis sensors such as those documented by ATI report forces along x, y and z and torques about those axes.
The reading depends on the sensor origin and coordinate frame. Moving the reference point changes the reported torque because the same force has a different moment arm. Gravity from a tool or payload can also appear in the measurement unless it is compensated.
Force–torque and tactile sensing are complementary
A wrist sensor can measure the net load transmitted through an arm but cannot normally show which fingertip or surface region produced it. A tactile array can preserve local pressure or shear while missing loads outside its instrumented area. Joint-torque estimates infer interaction through the mechanism and are not identical to a calibrated wrench measurement.
Controllers often use force–torque feedback for insertion, polishing, compliant motion, collision detection or payload estimation.
Wrench data needs more than six numbers
The record should include force and torque units, axis order, coordinate frame, reference point, sampling rate, calibration matrix, zeroing procedure, filtering, range and saturation. ROS 2's Wrench message separates force and torque; a stamped form is needed when timestamp and frame identity matter.
Dataset users should know whether gravity and tool weight were removed, whether values are raw or compensated, and where the sensor is mounted. Without that context, equal six-vectors can describe different physical loads.
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Related terms
Hardware & control
Tactile sensing
Tactile sensing is the detection and measurement of physical contact properties at a robot's surface or contact interface. Depending on the sensor, it can report pressure or force distribution, contact location, shear, vibration, slip, texture, temperature, or deformation. Tactile data complements vision by measuring interactions that may be hidden at the point of contact.
Hardware & control
Impedance control
Impedance control regulates the dynamic relationship between a robot’s motion error and the force or torque it exerts, usually by giving the robot virtual stiffness, damping and sometimes inertia. It lets an end effector or limb yield predictably during contact instead of trying to hold an exact position regardless of interaction forces.
Hardware & control
Torque control
Torque control is a control mode in which desired joint torques, or equivalent linear forces, are the command variables sent to a robot’s low-level actuators. Unlike position control, it does not directly command where each joint should be. Motion and contact instead emerge from the applied efforts, robot dynamics, feedback, constraints and any higher-level controller.
Hardware & control
Gripper
A gripper is a robot end effector designed to seize and hold an object. It may use fingers, jaws, suction, magnetism, adhesion, or another grasping mechanism. A gripper can open and close with one command or expose several independently controlled joints, but it is not synonymous with every end effector or with a complete robot hand.
Hardware & control
Coordinate frame
A coordinate frame is a defined origin and set of oriented axes used to express positions, orientations, motions, forces, or other spatial quantities. A value has no complete geometric meaning until its frame and convention are known. Transformations relate measurements expressed in frames such as world, robot base, camera, end effector, object, or sensor.