Digital-Triplet: a new three entities digital-twin paradigm for equipment fault diagnosis

Current equipment fault diagnosis faces challenges due to the difficulties in arranging sensors to collect effective data and obtaining diverse fault data for studying fault mechanisms. The lack of data results in disconnection between data from different spaces, posing a challenge to forming a closed loop of data and hindering the development of digital twin (DT) driven fault diagnosis (FD). To address these issues, a new DT paradigm Digital-Triplet is proposed. This paradigm comprises three entities: a physical entity, a semi-physical entity, and a virtual entity. A semi-physical entity is created by implementing the "six-D" process on the physical entity. A new six dimensional structure is formed through the addition of the semi-physical entity. The new structure streamlines the construction of fault datasets, enhances sensor data acquisition, and tightly links different data spaces, thereby promoting the application of DT in equipment FD. Subsequently, the elevator is selected as a case study to illustrate the Digital-Triplet framework in detail. The results demonstrate that the Digital-Triplet framework can effectively expand the fault dataset and improve data collection efficiency through optimized sensor placement, thereby promoting fault diagnosis.