Evaluating Strategies to Mitigate Jamming in Electromechanical Actuators for Safety Critical Applications

Abstract

In this paper various techniques to mitigate jamming in Electromechanical Actuators (EMA) for safety critical applications in aerospace are evaluated. This paper highlights and assesses what has already been achieved and thechallenges still to be addressed. Through Hierarchical Process Modelling (HPM), it was identified that Prognostics and Health Monitoring (PHM) and achieving fault tolerant designs in EMAs could be considered as means to mitigate jamming. The evaluation of past research revealed that achieving a fault tolerant EMA system through a reliable and robust anti-jamming system is currently at an early development stage for implementation within safety critical systems due to the increased design complexity (the antijamming system may even require PHM functionality itself). It was concluded that a hybrid diagnostic approach to predict the onset of jamming would be the most optimal approach by using a combination of model based and data-driven techniques to capture any discrepancies between the predicted and observed behaviour to isolate and identify faults. Furthermore, in order to achieve a robust and reliable hybrid diagnostics functionality (to mitigate EMA ballscrew jamming), recommendations were made to improve modelling fidelity and test stand analysis methodology, these are discussed in more detail in this paper.