Beside the main functions related to the control and transformation of power, safety-critical electromechanical actuators require many additional functions for power routing, protection and limitation. In practice, these functions are implemented mechanically because their realization at motor drive level is not acceptable for performance and reliability reasons. Contact forces play a major role in these mechanical devices (e.g. endstop, lock, brake, torque limiter, etc.), being either functional to serve the need, or parasitic due to their alteration of performance. The virtual prototyping of such mechanical power management functions therefore requires normal and tangent forces to be modelled with the right level of realism and reduced complexity.

This communication provides some proposals to be used as foundation for the system-level modelling and simulation of these types of mechanical power elements that can be found in electromechanical actuators. Special focus is given to the model architecting, decomposition and block-diagram implementation, using the example of normal contact forces. The illustrative example concerns an integrated landing gear extension/retraction electromechanical actuator which embeds free-fall and autolock features. It shows how a well implemented single model (e.g. generic normal contact force model) combined with a right model decomposition can meet various modelling needs (e.g. droppable end-stop, lock and shearable axial stop).

The proposed models are made compatible for integration in a 2x1D mechanical model architecture (axial and rotational motion) developed by the authors in previous reported work.

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