School of Mechanical Engineering;
Xi’an Jiaotong University;
Key Laboratory of Education Ministry for Modern Design and Rotor-bearing System;
Xi’an Jiaotong University;
Engineering Workshop;
Xi’an Jiaotong University;
State Key Laboratory for Manufacturing Systems Engineering;
Xi’an Jiaotong University;
Instantaneous; rotational; speed; Optical; encoder; Localized; fault; Multistage; gearbox;