Detection of suspended monorail track irregularity based on inertial navigation system and high-speed laser scanner

Track irregularities are crucial in the study of suspended monorail transportation systems. However, few studies have been conducted on the irregularities and detection principles of suspended monorail tracks (SMT). This study presents a continuous detection principle for track irregularities of suspended monorail beams using an inertial navigation system and a high-speed laser scanner. A motion trajectory calculation and bias correction formula are derived from the motion attitude of the detection trolley, facilitating the modeling of long-wave irregularities. A calculation model for short-wave irregularities is built through feature point extraction, data fitting, and spatial coordinate transformation of point cloud data. Based on these calculation models, an irregularity detection system for SMT was developed. To validate its accuracy and reliability, a field test was conducted on a 2-km experimental line using both the detection system and portable equipment. The test results from the detection system were in close agreement with those from the portable equipment, validating its accuracy. The irregularities of the experimental line included several periodic irregularities related to the unique structure of the track beam, which significantly impact ride comfort and the operational safety of the vehicle.