• Algorithm Monitoring
• Electro-mechanical actuator
• Fail-Safe
• Jamming Monitor
• Uncommanded Movement Monitor

This thesis deals with the design modelling and simulation of electro-mechanical actuation systems for safety-critical applications aircraft.
The work has been developed in the context to a research collaboration between Dipartimento di Ingegneria Civile e Industriale of the University of Pisa and Mecaer Aviation Group company to support the design of the electro-mechanical actuation system for the nose wheel steering system of a modern light jet aircraft.
This actuator is designed to be controlled in position, so it is equipped with six sensors.
Through non-linear modelling and simulation, it has been possible to study the stability and control of the nose wheel steering actuator.
Once validated the control laws of the system, particular attention has been focused on modelling of wheel-runway loads, free plays and sensors.
With the complete model, different tests have been made in order to obtain a performance characterisation as well as to analyse the uncertain parameters.
Finally, actuator monitors have been developed through fault-diagnosis algorithms, in order to detect jamming and uncommanded movement of the nose wheel steering actuator.