Gearbox torque measurement system

A gearbox system for connection to a motor (24), the gearbox system comprising:

• a structural ground (G) to which the motor (24) is fixedly attached;
• a differential gear system (12) including an input element (14), a transmission output element (16), and a measurement output element (18), wherein the transmission output element (16) rotates in response to rotation of the input element (14) and the measurement output element (18) reacts an output torque transmitted by the transmission output element (16) by providing a reaction torque equal and opposite to the output torque;
• a rotatable input shaft (20) driven to rotate by the motor (24) and connected to the input element (14), wherein the input element (14) rotates in response to rotation of the input shaft (20);
• a rotatable output shaft (22) driven to rotate by rotation of the transmission output element (16), wherein the rotatable output shaft (22) transmits the output torque;
• a measurement member (26) connected to and arranged between the measurement output element (18) and the structural ground (G);
• and
• a stationary sensor (30, 30′) associated with the measurement member (26) or the measurement output element (18) for measuring at least one of (i) a deformation of the measurement member (26), (ii) an angular displacement of the measurement output element (18), (iii) a force applied by the measurement member (26), and (iv) a force applied by the measurement output element (18), the measurement by the stationary sensor (30, 30′) being proportional to the output torque, wherein the stationary sensor (30, 30′) generates a signal representative of the output torque.