A robot comprising: a base; an articulated arm extending distally of the base and including two arm members coupled by a joint; a motor; a gearbox having an input shaft coupled to an output of the motor and an output shaft configured to drive relative motion of the arm members about the joint; a position sensor configured to sense relative position of the arm members about the joint; and a control system coupled to the arm configured to drive the motor, the control system being arranged to perform a calibration operation to estimate torque loss in the gearbox by the steps of (i) estimating the inertia of the portion of the arm distal of the joint for motion about the joint; (ii) applying a determined drive power to the motor; (iii) receiving from the position sensor position data indicating the motion of the arm in response to the applied drive power; and (iv) estimating the torque loss in the gearbox in dependence on the estimated inertia, the determined drive power and the position data.

A method, device, and computer program product for compensating robot movement deviations caused by a gear box as well as to a robot arrangement including such a device. The device has a drift estimating block configured to obtain motor data ({dot over (q)}.sub.r) and motor torque data () related to the motor, determine a measure of the temperature of the gear box based on the motor data ({dot over (q)}.sub.r) and motor torque data () and estimate the drift (q) based on a drift value of the robot section, the drift value in turn being obtained based on the gearbox temperature measure and a gravitational torque (.sub.grav) of the motor, and a drift adjusting block (44) configured to adjust a control value (q.sub.r) used to control the positioning of the robot based on the estimated drift (q).

A method for controlling an electric actuation assembly with improved accuracy in controlling the torque or force generated. The method includes applying a plurality of known first output forces and recording a plurality of first input intensities for a first movement direction of the output; establishing, by interpolation, a first characteristic function; applying a plurality of second known output torques and recording a plurality of second input currents for a second movement direction of the output opposite to the first direction; establishing, by interpolation, a second characteristic function; establishing, on the basis of the first characteristic function, the second characteristic function, a magnetic constant of the motor and a reduction ratio of a gearbox, and a control correction coefficient; and controlling the actuation assembly by applying the control correction coefficient.