# Vision Systems for a UR5 Cobot on a Quality Control Robotic Station
## 4 Result Investigation  
This chapter presents an analysis of the results of a series of measurements carried out to determine the level of measurement noise, accuracy, and repeatability of the deployed vision system (with the proposed and implemented algorithms). A semi-finished product (Figure 11) with an irregular shape, made using 3D-printing technology, was designed to carry out a series of measurements. The measurement sequence's first stage involved taking 100 photos (in the optimal position of the camera's field of view, which is the center of the optical axis), in identical lighting conditions and system configuration. In the next step, the location and diameter of the internal holes (1-4) (Figure 11b) and the external diameter (5) (Figure 11b) of the prepared element were computed. A series of measurements were carried out both without and with backlight lighting (under the fluorescent lamp lighting system installed in the room). The results which were obtained are presented below (Table 1) (Figures 17-19), including a comparison of the following values: standard deviation, standard uncertainty, relative error, absolute error, and mean value. The next series of measurements concerns determining the accuracy and repeatability of the developed vision system (encompassing implemented methods). The collected data will also make it possible to draw a map of measurement error variability, the analysis of which will allow for the determination of the camera's image space where the measurement accuracy is the highest. The described measurement experiment involved taking a series of 50 photos, in each of 40 positions, in the camera's field of view. The photos were taken for the case without and with backlight lighting (under the fluorescent lamp lighting system in the laboratory room). The next step, like the first measurement session, was determining the basic geometric dimensions of the part. The results are presented below (Tables 2 and 3) (Figures 20-25), including the selected maps' standard deviation (for inner diameters No. 1 and 3 and outer diameter). Figure 16: The result of the measuring tool, with internal contours (holes) and a rectangular area covering the external contour of the object (representing the outside dimensions: width, height). Red boxes—detected object, green border—detected inner contours. Analyzing the obtained results (Tables 2 and 3) additional backlight lighting significantly improved the average accuracy and repeatability of the vision system, whereas, in the case of the laboratory room illumination system (without backlight), the average accuracy is estimated at the level of 0.325 mm, and for backlight illumination, this is 0.031 mm. The plotted error maps reveal that the error distribution is not constant throughout the camera's field of view. The values of the determined relative and absolute errors, standard deviation estimators, and measurement uncertainties showed the influence of the semi-finished product's location on the accuracy and repeatability of the measurements. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Without Backlight Lighting**} \\ \hline
**Feature** & **Mean Value [mm]** & \begin{tabular}{c} **Standard** \\ **Deviation [mm]** \\ \end{tabular}  & \begin{tabular}{c} **Standard** \\ **Uncertainty [mm]** \\ \end{tabular}  & \ \begin{tabular}{c} **Average Absolute** \\ **Error [mm]** \\ \end{tabular}  & \begin{tabular}{c} **Medium Relative** \\ **Error [\%]** \\ \end{tabular}