Worthy test programmes and developments of smart electromechanical actuators

Abstract

Early aircraft flight control systems were totally manually operated, that is, the force required to move flight control surfaces was generated by the pilot and transmitted by cables and rods. As aerodynamics and airframe technology developed and speeds increased, the forces required to move control surfaces increased, as did the number of surfaces. In order to provide the extra power required, hydraulic technology was introduced. To date, the common element in the development of flight control systems has been, mainly, restricted to this type of technology. This is because of its proven reliability and the lack of alternative technologies. However, the technology to build electromechanically actuated primary flight control systems is now available. Motors developing the required power at the required frequencies are now possible (with the use of high energy permanent magnetic materials and compact high speed electronic circuits). It is this particular development which may make the concept of an ‘all electric aircraft’ realizable in the near future. The purpose of the all electric aircraft concept is the consolidation of all secondary power systems into electric power. The elimination of hydraulic and pneumatic secondary power systems will improve maintainability, flight readiness and use of energy. This paper will present the development of multi-lane smart electric actuators and offer an insight into other subsequent fields of study. The key areas of study may be categorized as follows. State of the art hydraulic actuators. Electromechanical actuator system test programmes. Development of electromechanical actuators. Modelling of electromechanical actuators.

Force equalisation in torque-summed electromechanical actuators

“…The basic structure and operation of classical dc machines were given in [33,4], where the author developed lumped models for the brushless dc motors. In the 3-phase model, these lumped models represent the models for each of the single phases, and will take into account the effect of phase shifting and the mutual inductance [34].…”

“…Studies that addressed force fighting include the studies in [26,27,28,29,30,31,32,33,4,34]. The authors in [26] described the electromechanical actuation systems in the X-38 project, which main drive was to perform multiple unmanned drop test vehicles for unmanned space flight Proto-Flight Vehicle 201 (V-201).…”

“…The 4-lanes architecture that was developed by the Queen Mary University of London Group was designed to move the inner board aileron on the Sea-Harrier. The actuator matched its hydraulic counterparts in operation, redundancy and safety [4,33,34]. The group made a significant contribution by considering different architectures with various levels of modelling complexity and have investigated different threshold setting methods and different crossmonitoring techniques.…”

Hardware versus lumped cross-monitoring in smart multilane torque-summed electromechanical actuators

“…This section gives brief descriptions of contributions to state-of-the-art actuation systems by major developers. Annaz [1] gave detailed descriptions of developments in hydraulic, electromechanical, and pure electric actuators. Here, only the main contributors to electromechanical actuators will briefly be listed.…”

“…Models were developed by many authors, including those in references [16] to [20], which were summarized in reference [1]. This section will list the electrical and mechanical equations for the lumped and three-phase models, and the reader is advised to consult reference [1] for more details.…”