Accuracy of Instantaneous Angular Speed Signals for Fault Diagnosis of Planetary Gears: A Review

Planetary gears are an important component in the transmission system of advanced equipment, such as helicopters, wind turbines and power plants. Fault diagnosis of planetary gears can effectively reduce the huge losses caused by machine failure or downtime, and thus bring significant benefits to many industries. Traditional fault diagnosis of planetary gears mostly uses translational vibration, acoustic emission, electrical signals, etc., however, this cannot effectively address the problems of long transmission paths and multi-frequency coupling modulation in planetary gears. In recent years, encoder signals have attracted widespread attention in mechanical condition monitoring, because the instantaneous angular speed (IAS) signal obtained from the encoder signal contains a large amount of valuable fault information. This paper summarizes main factors that have impacts on accuracy of IAS signal estimation by reviewing edge-cutting solutions to effective fault diagnosis of planetary gears.