Fault Diagnosis Reasoning Algorithm for Electromechanical Actuator Based on an Improved Hybrid TFPG Model

As a new generation of power-by-wire actuators, electromechanical actuators are finding increasingly more applications in the aviation field. Aiming at the application problem of the fault diagnosis of the electromechanical actuator, an improved diagnosis reasoning algorithm based on a hybrid timed failure propagation graph (TFPG) model is proposed. On the basis of this hybrid TFPG model, the activation conditions of OR and causality among nodes are given. The relationship discrepancy node is transformed into a relationship node and discrepancy node, which unifies the model storage process. The backward and forward extension operations of hypothesis generation and updating are improved. In the backward expansion operation, the specific process of backward update from non-alarm nodes is given, and the judging logic of the branch of relationship nodes is added, which guarantees the unity of the algorithm framework and the accuracy of the time update. In the forward expansion operation, the update order is adjusted to ensure the accuracy of the node update for the case of multiple parents. A hybrid TFPG model of the electromechanical actuator is established in the general modeling environment (GME), and a systematic verification scheme with two simulation types is tested with the application of the P2020 reference design board (RDB) and VxWorks 653 system. The results show that the proposed algorithm can realize the fault diagnosis of the electromechanical actuator as well as fault propagation prediction.