Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Improved actuator concept

Regarding the electrical motors, we must admit that there has not been a great forward step. However, gearbox and winch (so- called drum or barrel) have been redesigned in order to mainly reduce the overall weight of actuation system. So, the achieved mass saving is the half one of the homologous PTD actuator assembly through optimisation of both items.

The planetary gearbox solution from PTD was replaced by a wormgearbox solution due mainly to
- its lower cost and weight for the same torque capacity,
- In addition it features a high static irreversibility, so that contributes to the desired locking feature even on presence of high output torque through output shaft when control line must be hold in certain position

Despite that control of the system was achieved with no major problems (as proven during flight tests) this type of worm gearbox revealed some drawbacks that shall be accounted for future optimisation stages:
- the wormgearbox model shows a behavior clearly non-linear during starting up and stops, which is closely related to the fact of presenting two different efficiencies (static and dynamic) depending of the operation regime.
- This is also aggravated by the high degree of intermittency requested.

Controller parameters.
The programming of servo controllers was optimised in the basis of the new FastWing guiding & flare performances. In particular, The Position Control Loop - proportional, differential and integral terms � was revised, so they were proven to be stable and provide sufficient position accuracy.

Actuator performances
- The actuation system was successfully tested on ground with the new control parameter set
- It was proven that actuator system is able to start up, control, and brake the specified loads for both guiding and flare cases.

Applications: Performances optimisation for electrical actuation systems to be used on UAVs (Unmanned Aerial Vehicles).

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28906 MADRID