A force-torque sensor (FT sensor) is a transducer mounted at a robot’s wrist or tool centre point that simultaneously measures all six components of mechanical load: three orthogonal forces (Fx, Fy, Fz) and three orthogonal torques (Tx, Ty, Tz). These measurements enable the robot controller to monitor contact forces in real time, supporting force-controlled assembly, surface-following tasks, human-robot contact detection, and safety-critical power-and-force limiting under ISO/TS 15066. FT sensors are the primary feedback device for impedance and admittance control strategies.