Compensating robot movement deviations

A device for compensating robot movement deviations caused by a gearbox connected between a robot section and a motor controlling the movement of the robot section, the device comprising:

• at least one drift estimating block configured to:
• obtain motor data of the motor;
• obtain motor torque data;
• determine a temperature measure gearbox based on the motor data and the motor torque data;
• estimate a drift compensation based on a drift value of the robot section, said drift value being obtained based on the gearbox temperature measure and a gravitational torque of the motor;
• the drift estimating block having a temperature dependent measure forming element configured to determine the gearbox temperature measure through low pass filtering the motor data, where the result of the filtering is the gearbox temperature measure;
• the drift estimating block having a temperature measure handling element configured to obtain the drift value by applying the gearbox temperature measure and the gravitational torque in known relationships between drift value, temperature measure, and gravitational torque;
• and
• a drift adjusting block configured to adjust a control value used to control the positioning of the robot based on the estimated drift compensation.

A robot arrangement comprising an industrial robot and a device for compensating robot movement deviations,

• the industrial robot including:
• a number of moveable arm sections,
• at least one motor for moving a corresponding arm section, and
• a gearbox between the motor and the arm section,
• the device for compensating robot movement deviations including:
• a drift estimating block configured to obtain motor data of the motor, obtain motor torque data, determine a temperature measure of the gearbox based on the motor data and the motor torque data, and estimate a drift compensation based on a drift value of the robot section, said drift value being obtained based on the gearbox temperature measure and a gravitational torque of the motor,
• the drift estimating block having a temperature dependent measure forming element configured to determine the gearbox temperature measure through low pass filtering the motor data, where the result of the filtering is the gearbox temperature measure,
• the drift estimating block having a temperature measure handling element configured to obtain the drift value by applying the gearbox temperature measure and the gravitational torque in known relationships between drift value, temperature measure, and gravitational torque, and
• a drift adjusting block configured to adjust a control value used to control the positioning of the robot based on the estimated drift compensation.

A non-transitory computer program product for compensating robot movement deviations caused by a gearbox connected between a robot section and a motor controlling the movement of the robot section, the computer program product comprising a data carrier with computer program code which when run in a device for compensating robot movement deviations, causes the device to:

• obtain motor data of the motor;
• obtain motor torque data;
• determine a temperature measure of the gearbox based on the motor data and motor torque data, said determining the gearbox temperature measure includes low pass filtering the motor data, where the result of the filtering is the gearbox temperature measure;
• estimate a drift compensation based on a drift value of the robot section, said drift value being obtained based on the gearbox temperature measure and a gravitational torque of the motor by applying the gearbox temperature measure and the gravitational torque in known relationships between drift value, temperature measure, and gravitational torque;
• and
• adjust a control value used to control the positioning of the robot based on the estimated drift compensation.