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).

The invention relates to a demolition robot (1), comprising a cable (12) intended to be connected to an electric network to power a motor (21), a pump (22) that is powered by the electric motor for generating a hydraulic flow to consumers (13), wherein the motor (21) is activable at varying thermal load values (PT), depending on the current consumer's (13) need for hydraulic power, a control unit (24) arranged to receive information about the thermal load (PT) on the motor, to determine a partial thermal damage value (SL, SM, SH) at various thermal loads (PT) on the motor. To minimize the risk of thermal damage to the motor, the control unit (24) is adapted to compare said partial thermal damage values (SL, SM, SH) with a normative partial thermal damage (A) and is adapted to limit the thermal load (PT) on the motor (21) to a maximum allowable thermal load value (PTmax), if the partial thermal damage value (SL, SM, SH) exceeds the normative partial thermal damage (A) at a predetermined value (A).

Methods and apparatus for adjusting and controlling a robotic manipulator based on a dynamic manipulator model. A model for gear mechanism friction torque is determined for at least one axis, based on driven axis speeds and accelerations, and on a motor temperature on the drive side of one of the motors that is associated with the axis. The model is used to determine target values, such as motor position or current. The gear mechanism friction torque that complies with the model is determined in accordance with a gear mechanism temperature.