Method and apparatus for controlling an industrial robot

An equipment for controlling an industrial robot, which robot has a plurality of rotation and/or translation axles, the equipment comprising:

• at least one motor at each of said axles for generating desired movements of the arms and/or the wrist, of which the robot is constituted,
• least one sensor at each of the axles for measuring axle angle and/or axle position,
• at least one servo for each of the axles for controlling the motors based on measurement values from the sensors,
• at least one path generator for generating at least one reference ((φref, φref, πffw) for each of the servos,
• an apparatus at least one of the axles, which apparatus comprises a first device for calculation of the expected interference moment value (πdistexp) of said axle when the movable parts of the robot is not exposed to any external forces by interaction with an operator or other things in the surroundings of the robot, and a second device for comparing this expected interference moment value (πdistexp) with values of the moment reference (πmr) of the servo and/or with values of the moment (πm) of the motor and/or with values of moment measured on the axle with sensors and for forming, based on this comparison, a signal (πcontrol) for controlling the path generator,
• wherein a function generator included in said apparatus for supplying to the servo at least one reference signal ((φref2 and/or (φref2 and/or πffw2) for generating a to and fro motion of the axle controlled by the servo, and means for calculation of said values of the moment reference (πm) of the servo and/or of the moment (πm) of the motor and/or the moment of the axle by mean value formation (in the unit 18B according to formula 4B).