# Experimental Study of the Vibrations of a Roller Shutter Gripper
## 4 Evaluation
### Testing the Properties of the Gripper on a Real Test Bench  
The designed roller shutter gripper is dedicated to handling full layers of products, which requires a specific loading method. The loading process involves transporting full layers of products inside the gripper after positioning it at the picking point. A crucial point in this process is the accurate positioning of the gripper in direct contact with the conveyor. Considering the large size and weight of the layers to be conveyed, it is necessary to reduce the weight of the gripper so that it meets the robotization requirements of the industrial process. However, reducing the mass of the gripper also affects its stiffness, which results in a deterioration of the quality of the industrial process and an increased production cycle time. The authors conducted a study to determine the nature of vibrations occurring when the developed gripper stops at a process point. The impact of the motion parameters of the industrial robot on the magnitude of these vibrations was also investigated. This will allow proper parameterization of the robot's movements to reduce the occurrence of the undesirable phenomenon of structural vibration. Figure 13 presents an example graph of the robot's acceleration for the \(X\)-axis, along which the robot's movement was performed when approaching the process point. The graph shows characteristic sections where the robot is stationary, starts a movement, accelerates to a preset speed, moves at a preset speed, brakes, and stops at the process point. Obtained results were processed using programs and scripts developed in the MATLAB environment. Data analysis was preceded by data preparation. This consisted of the following activities:  
* Importing the measurement data into the MATLAB structure;
* Determining and selecting the range of data for analysis;
* Reducing the constant bias component by examining the measurement silence period. Figure 14 shows gripper acceleration plots measured with a triaxial XSENS sensor. Figure 13: Acceleration graph when the robot moves from point _P1_ to point _P2_. 1—robot is stationary before starting to move, 2—accelerating to reach the set speed, 3—moving at a constant speed, 4—braking before the end point, 5—stopping at the process point. A detailed analysis of tool vibration (Figure 15) was carried out for the tool stop area at the process point (red box in Figure 14). Considering the implementation of the process, the study was focused on the analysis of acceleration, velocity and displacement related to the \(X\)-axis (the direction of the robot's approach to the retrieval point). A series of tests were carried out for the programmed speeds of the robot (4000 mm/s, 3000 mm/s, 2000 mm/s, and 1000 mm/s) while changing the acceleration coefficient (ACC100, ACC75, ACC50, ACC25). Figure 16 shows the acceleration graphs of sensors mounted on the robot's flange and on the gripper for the parameters V4000 and ACC100. A similar pattern of accelerations was observed for the other cases studied; the results are shown in Table 2.  
Figure 14: Graphs of accelerations acquired with MTi XSENS sensors mounted on the gripper for V4000, ACC100 parameters for the \(X\), \(Y\), and \(Z\) axes. Figure 15: Acceleration graph area after robot stop for V4000, ACC100 parameters for the \(X\), \(Y\), and \(Z\) axes. From the graph of one robot cycle (Figure 16, red box), the moment of stopping at the measuring process point was selected (Figure 17). A discrepancy was observed in the value of accelerations measured by sensors located on the robot's flange and on the gripper. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Test** & \begin{tabular}{c} **Robot** \\ **Target** \\ **Speed** \\ \end{tabular}  & **ACC** & \begin{tabular}{c} **Maximum** \\ **Acceleration—** \\ **Flange** \\ \end{tabular}  & \begin{tabular}{c} **Maximum** \\ **Acceleration—** \\ **Gripper** \\ \end{tabular}  & \begin{tabular}{c} **Maximum** \\ **Acceleration—** \\ **at the Process** \\ **Point—** \\ \end{tabular}  & \