Assessment of tool platform micro vibrations induced by moving vehicles in hi-tech factories

Abstract

This study explores the micro vibrations of floors and tool platforms induced by internal moving automated guided vehicles (AGVs) in hi-tech factories. The equation of motion of a simplified multi-span floor (or beam) system installed with a tool platform under AGV moving forces generated by a modified Kanai-Tajimi power spectral density (MKT-PSD) function is derived. Dynamic time history analyses of the continuous beam model travelled by different AGV weights are performed. The corresponding root-mean-square (RMS) floor and platform vibration spectra are obtained by using a one-third octave band spectrum analysis and in turn used to compare with the micro vibration criterion. Simulated results indicated that the floor and platform vibrations increase with the AGV weight. For the maximum AGV weight considered, the floor vibration exceeds VC-A, while under the minimum AGV weight, the floor vibration reaches VC-B which is required by the vibration-sensitive tools. Moreover, the platform vibrations are far more than VC-A regardless of the AGV weight. Therefore, the introduction of a proper vibration control scheme is recommended to suppress the excessive micro vibrations of the floors and taller tool platforms.