Dynamic Optimization Design of the Base Plate Structure of a Track Inspection Robot based on Modal Analysis

Abstract

The detection accuracy of track-based inspection robots is directly related to the smoothness of equipment operation on the track. Harmful vibrations caused by defects in the dynamic characteristics of the equipment structure are the fundamental reason for blurred monitoring images and distorted data. Addressing the issue of insufficient rigidity in the load-bearing base plate of a certain type of track-based inspection robot, this paper conducts analysis and parameter optimization based on the resonance risk induced by dense low-frequency modes. The parameterized finite element model, after simulation analysis using the Constrained Modal Analysis tool, reveals that the original structure's 3rd-order natural frequency within the narrow frequency band from 90 Hz to 102.60 Hz highly overlaps and is densely distributed with the drive system's second harmonic excitation frequency band from 90 Hz to 110 Hz. The same frequency can cause equipment resonance and pose a hazard to reliability. Modal analysis of the optimized structure shows significant improvement in the dynamic performance of the equipment structure, with the fundamental frequency increasing from 99.60 Hz to 186.58 Hz (an increase of 87.3%). The original dense mode group is effectively separated, the distribution of frequencies at various orders tends to be reasonable, and the natural frequencies are all migrated to the safe frequency band, resolving the resonance risk from the source. Although the optimized model weighs 0.9 kg more (an increase of 36.3%), the resulting improvement in dynamic performance is more significant. This study verifies the effectiveness of the structural dynamic design optimization method based on modal analysis, providing a reference for early risk prediction and design iteration of similar equipment.