HIGHLY ACCURATE INTEGRATION OF TRACK MOTIONS

According to the largeness of the workpieces in several industrial environments, a great number of industrial robots is placed on external track motions, so called 7 axes, as for automotive or aircraft industries. Flexible automation today requires absolute high accuracy. For example modern robotics deals with offline programming, copying programs between similar working cells, reflecting programs or image processing for 3D-pose estimation. All these tasks need absolute high accuracy and in fact, there have been many investigations for increasing the accuracy of single robots in the past few years. In contrast to that the use of track motions will dramatically increase the position error and badly influence the static behaviour of the robot system. The main reasons for these additional errors are the incorrect identification of the main track direction and furthermore, very crucial, the non-linearities of the TCP (Tool Center Point) during the robots motion on the track. This article will introduce a new method of identification and mathematical integration of linear tracks. At first we present the method for measuring and generating profiles of single tracks by making use of the discrete fourier transformation (DFT) and cubic spline interpolation. Then a method for recalculating offline generated programs for real environments is presented, followed by a method for copying programs taking two profiles of track motions into consideration. Finally some measurement results are shown.