Method for control of an industrial robot along a given track

Abstract

A method for control of the movement of the movement of an industrial robot along a given track (P,-P,) with a desired track speed (v), which industrial robot has a number of movement axes and for each axis servo equipment for control of the axis movement in accordance with reference values ({overscore (&tgr;)},) supplied thereto. First, those axis angles ({overscore (&phgr;)},) which are needed for assuming the next position on the track are calculated. In dependence on the calculated axis angles and a first mathematical model, which describes the static and dynamic properties of the robot, for each one of the movement axes that torque ({overscore (&tgr;)}=(&tgr;,, &tgr;,. . . &tgr;,)) is calculated which is required for assuming the next position. The load (t) is calculated at one or more mechanically critical points for the calculated axis angles ({overscore (&phgr;)},) with the aid of a second mathematical model, which describes the load of the robot at the critical points. For each one of the axes, the calculated torque ({overscore (&tgr;)}) is compared with a maximum permissible torque, ({overscore (&tgr;)},), and the load (t) is compared with a maximum permissible load (t,) for the critical point. If the calculated torque exceeds the maximum permissible torque for any axis, or if the calculated load exceeds the maximum permissible load for any critical point, then the track speed (v) is reduced and the reference values for the servo system {overscore (&tgr;)},=(&tgr;,, &tgr;,. . . &tgr;,, are calculated in dependence on the reduced track speed.