CONTROLLER FOR ROBOT AND INVERSE TRANSFORMING METHOD FOR ROBOT

A robot has a vertical 6-axis articulated arm having an offset arm having a fifth axis and length link, and mutually linking fourth and sixth axes. The fourth and sixth axes shaft centers are parallel. The articulated arm has a head portion designated as a control point. A position and an orientation targeted to the control point is processed by an inverse transform to calculate angles of the axes. A provisional target position of the sixth axis is obtained by subtracting the link length from a target position of the sixth axis. The link length to the provisional target position is given zero to perform the inverse transform process. Processed results are evaluated. Until a difference between a calculated sixth-axis angles and provisionally decided sixth-axis angles becomes equal to or less than a predetermined value, processes started from the angle provisional decision of the sixth axis are repeatedly performed.