# Industrial Robot Positioning Performance Measured on Inclined and Parallel Planes by Double Ballbar
## 3 Experiment Preparation  
The LR Mate 200 iC robot was chosen to conduct the measurement on, with the selection of the position and orientation of the desired circular path in the robot's workspace being the first step. For this purpose, information from the ISO 9283 standard was applied, where the recommended procedure for measuring performance criteria is based on the so-called ISO cube. It is an imaginary cube, its vertices marked C1 to C8, and it is placed in the robot's workspace, with its edges parallel to the robot's basis or its world coordinate system. Based on the industrial robot type, a plane containing points is placed in the said cube, with the points defining the individual paths used for measuring the performance criteria. In the case of robots with six controlled axes, the inclined plane determined by the vertices C1-C2-C7-C8 is selected (see Figure 6) [6]. For the purpose of the experiment, a  
Figure 5: The course of the motion of the individual robot joints during the TCP movement in a circular path in the ZX plane. circle required for conducting the measurement with the Renishaw Ballbar QC20-W is be placed on this plane. As for the circle diameter, a basic nominal radius of 100 mm, which had been used in the past experiments, was chosen so that it would be easier to compare the measurement results. Furthermore, it was necessary to determine the position of the ISO cube or the center of the circle in the Fanuc LR Mate 200 iC robot's workspace. The base consisted of the coordinates of the center of the circle, used in the present volumetric analysis (see Table 2). However, this position was adjusted so that when the circle was tilted below the angle of \(-45^{\circ}\), the measuring apparatus did not collide with the workbench on which the Fanuc robot was placed. At the same time, the possibilities of the robot arm's reach in the movement along a defined path were also taken into account. As a result, the coordinates of the center of the circle [X = 200; Y = 400; Z = \(-200\)] were defined by the Fanuc Roboguide HandlingPRO 8 software. Two possible configurations of the robot arm correspond to the defined position and orientation of the circle, as well as to the circular path required for the measurement. Specifically, this is a configuration related to the J5 joint position, which is referred to as the N-NOFLIP (joint J5 \(<0^{\circ}\)) and, as an F-FLIP (joint J5 \(>0^{\circ}\)) position in Fanuc robots [35]. Both configurations are shown in Figure 7. The measurement was done for each of the two possible configurations of the robot arm. To carry out practical measurements, two jigs were designed and manufactured through 3D printing. These allowed the measuring apparatus to be clamped to the robot's  
Figure 6: ISO cube with a measuring plane, for robots with six controlled axes. Figure 7: Jigs for measuring in two selected measuring plane. (**a**) NOFLIP configuration; (**b**) FLIP configuration; (**c**) NOFLIP configuration. workbench while maintaining the defined coordinates of the center of the circle. The first of the jigs enabled a measurement at an angle of \(-45^{\circ}\) (Figure 7a,b). The second jig was used to conduct a standard measurement in the XY plane parallel to the benchtop (Figure 7c) while maintaining the same coordinates of the center of the circle as was the case with the inclined plane. The robot's control program was created in such a way that the center of the circle of a given radius was at the beginning of the User Coordinate System (UF) defined concerning the robot's WCS. Through a change in the position or the orientation of the user coordinate system, the program thus created allows a change in the position and orientation of the emergent circle. Thus, the same program is actually used for the desired circle on an inclined plane at an angle of \(-45^{\circ}\) and for the circle in a plane parallel to the benchtop.