PSI - Issue 42

Taško Maneski et al. / Procedia Structural Integrity 42 (2022) 1503–1511 T. Maneski at al/ Structural Integrity Procedia 00 (2019) 000 – 000

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These initial measurements unequivocally showed that the main support structure with columns and latticed beams as well as the substructural carrier system for supporting the robot did not have sufficient rigidity in the horizontal directions; only the rigidity in the vertical direction was satisfactory. The measured accelerations greatly exceeded the acceptable values.

Figure 11. Acceleration, measured in the time domain, of robot carriers 2

The second investigation was two months later, when the displacements and accelerations were measured only on robot 2 and its carrier. This was because robot 2 initially had had the most unfavorable characteristics. Displacement was measured using inductive sensors to determine relative movement of both the robot carrier and the support structure. The displacements were measured when robot 2 was painting only an upper or lower fender (displacements are shown in Figure 12). The absolute displacements of the robot carrier were much larger than the displacements of the support structure which shows the unfavorable dynamic behavior of the structure.

Vertical movement recorded by Micro-Epsilon sensors

Longitudinal movement recorded by Micro-strain sensors

Figure 12 Robot 2 movement [mm] measured during the second investigation (horizontal axis - time in 0.01s)

Figure 13. Accelerations of the robot 2 carrier in the time and frequency domains

Displacement amplitudes and acceleration values far exceeded acceptable limits, especially when the occasional longitudinal impact occurred. The very nature of these dynamic changes indicates poor performance of the machines. Simultaneous measurement of acceleration in the time and frequency domains was performed with the Microelectronics sensor, and the results are shown in Figure 13 (horizontal longitudinal direction is shown in blue, horizontal transverse direction in black, and vertical direction in red). It shows that acceleration in the vertical direction was still negligible at the time of the second investigation, but acceleration in the horizontal direction had