METHOD FOR CONTROL OF AN INDUSTRIAL ROBOT

A method for control of an industrial robot, which has a plurality of movement axes with a position sensor for each of said axes which is adapted to deliver an output signal which defines the current position of the axis, and a control system for control of the axes of the robot. Continuously during operation of the robot for at least one mechanically critical point (i) of the robot, the relevant load (.tau..sub.i) during a predetermined period of time (.DELTA.t) is calculated on the basis of the output signals (.phi..sub.1,.phi..sub.2 . . . .phi..sub.6) from the position sensors and a mathematical model of the robot. Further, the rate of fatigue ##EQU1## of the point is calculated on the basis of the calculated load and with knowledge of the fatigue strength (N.sub.ij) of the material at the critical point. The performance (.phi..sub.axis,max, .tau..sub.axis,max) of the robot is adjusted in dependence on the rate of fatigue and the desired service life (t.sub.life) of the robot.