Bond graphs aided development of mechanical power transmission for aerospace electromechanical actuators

The Bond-graph formalism is used to support the model based development of mechanical power transmissions in aerospace electromechanical actuators. The effort placed in architecting models injects the genes of performance to make them "ready for" incremental modelling covering various engineering needs: power sizing, dynamics, power/energy consumption, response to failure, etc. The model topology is addressed with consideration to model decomposition, mechanical / energy balance, and fault injection. Standardized mechanical body and interface are presented to limit the impact of the topological choice on the model response and ensure the sub-models interconnexion. The genericity of the model is increased at a little expense in complexity. These proposed concepts are illustrated using the example of a nut-screw. The nut-screw model is decomposed into perfect power transformation, frictional loss and compliance effect. Order of decomposition and causality at model's interfaces are considered. The proposed generic architecture is consistent with top-level as well as detailed modelling: influence of velocity, transmitted force, preload and temperature on friction, single parameter for backlash and preloading, simple implementation of jamming and free-run failures. The detailed model based on standardized component is finally presented and discussed.