Advance failure detection and diagnostics on primary flight control servo actuators augmented by collaborative robotics

Electro-Hydraulic Servo Actuators are the leading technology in the field of primary flight control. These components have been subjected to several studies to investigate new fault diagnostics procedures. Previous works have brought to an automatic test, designed with a sequence of signals able to assess the health status of the unit. Although the progress archived in fault isolation techniques, it is not always possible to precisely isolate two critical subassemblies of the A320 Elevator: servo valve and the recentering device. These two components are linked together by a complex mechanical kinematic chain that makes the fault isolation task particularly tricky. The present thesis, which is the outcome of a six months collaboration between Lufthansa Technik (LHT) and Polytechnic of Turin, tackles the problem with an original approach: exploiting collaborative robotics to perform automatic tests. The robot acts with high repeatability on the adjusting screw of the servo control that sets the force exerted by the recentering device. The system's response to this type of excitation is post-processed by an algorithm that automatically extracts new health features. The kinematic chain of the recentering device has been modeled with Simscape multibody to have the possibility of investigating the response of the system with specific mechanical degradation. The model has made it possible to assess the sensitivity of various health features affected by the presence of deterioration in the mechanical parts of the recentering device. The hypothesis of a correlation between health features and failure as well as the experimental setup and the post-processing code are the primary outcomes of the thesis, which constitutes the base for a future extensive experimental campaign.