Soft-Switchable Dual-PI Controlled Axial Loading System for High-Speed EMU Axle-Box Bearing Test Rig

A high-speed electric multiple unit (HS-EMU) bearing test rig that simulates the working conditions of axle-box bearings is an important performance evaluation device. Because of heavy working loads at high speed, two problems have been commonly encountered in testing industrial HS-EMU axle-box bearings on a conventional test rig, which are highly unbalanced axial load on its support bearings and adverse clearance effects on test bearings. This paper presents a new HS-EMU bearing test-rig design with a relatively complete dynamic model for its analysis and a direct force control strategy to overcome these problems. In this strategy, a dual proportional-integral (PI) controller with a fuzzy logic selectable soft switch has been developed. The control strategy can be easily implemented on an industrial programmable logic controller as it relies only on measured force values and requires a small amount of calculation. The bearing test-rig controlled system has been experimentally evaluated against a conventional PI controller.