# Impact of a Robot Manipulation on the Dimensional Measurements in an SPC-Based Robot Cell
## 5 Discussion  
It should be underlined that the primary goal of our research was not to confirm the ability of the measuring system but to investigate the influence of various robot interventions made with the measured object on the final dimensional measurements. In automated measurements in industry, it is assumed that the measurement uncertainty is much lower than in traditional, manual measurement methods. The main reason for this assumption is  
Figure 10: Measurement results for PKR object characteristic code 10 (height), code 100 (height), code 130 (diameter), and code 140 (height). Red, green, and blue lines represent individual measurements, while black lines represent the average measurement values. The absolute value of statistical parameters (\(C_{p}\), \(R\), and \(6\sigma\)) is not as significant as the decreasing/increasing trend. Scenario numbers appear on the horizontal axis. Figure 9: Measurement results for a Magnet characteristic code 30 (height) for all the measuring sets and the average. The red line represents the average of set 1, the green line represents the average of set 2, the blue line represents the average of set 3, and the black dotted lines represent individual repetitions of the desired set of measurements. The absolute value of statistical parameters (\(C_{p}\), \(R\), and \(6\sigma\)) is not as significant as the decreasing/increasing trend. Scenario numbers appear on the horizontal axis. human/operator influence on measurements. In the case of automated measurements, this influential factor is typically reduced or eliminated. As can be seen from a general observation of Figures 8-10, the robot actions do influence the dimensional measurements. Furthermore, various robot interventions do not have the same impact on the measurement capability of the measurement system. While observing more closely, Figures 8-10 in comparison to Figures 3 and 4, that describe the measurement codes, it turns out that the influence is noticeable in the length measurements (Magnet code 30, PKR codes 10, 100, and 140), while, in the spherical geometries, the influence is less recognizable (Magnet code 20 and PKR code 130). The results describing the measurement results obtained from the MSA study for the Magnet characteristic code 20 (diameter) are shown in Figure 8. Increasing the degree of the robot's manipulation (moving from scenario 1 to scenario 9) does not influence the dimensional measurements. The \(C_{p}\), \(R\), and \(6\sigma\) values do not change significantly from scenario 1 to scenario 9. Furthermore, their values remain similar for all three measurement sets, representing the different measurement methods (last column). Measurement set 1 consists of measurements with the Touch-trigger-based measurement method (red line), set 2 consists of measurements with SM (green line) and an increased number of sampling points, and set 3 consists of measurements with SM+, with an additionally increased number of sampling points (blue line). The black dotted lines represent repetitions of a particular measurement method for all the scenarios. As is clear from Figure 9, which represents the measurement results for the Magnet characteristic code 30 (height), various robot interventions influence the dimensional measurements. By increasing the degree of manipulation, the \(C_{p}\) value decreases and the values \(R\) and \(6\sigma\) increase from scenario 1 to scenario 9. Similar to the measurements of the Magnet characteristic code 20 are the curves describing \(C_{p}\), \(R\), and \(6\sigma\) for the Magnet code 30 for all three measurement sets corresponding to three measurement methods (Figure 9, last column). In all three cases, the \(C_{p}\) value decreases with an increase of the robot's degree of manipulation, which means an increase in the scatter of the measurement data (\(6\sigma\)). The Magnet object was our primary case study investigating the influence of robot manipulation on dimensional measurements in rectangular and spherical geometries.