The work deals with the development of deterministic model-based condition-monitoring algorithms for an electromechanical flight control actuator with fault-tolerant architecture, in which two permanent magnets synchronous motors are coupled with differential ball screws in speed-summing paradigm, so that the system can operate even after a motor fault, an inverter fault or a mechanical jamming. To demonstrate the potential applicability of the system for safety-critical aerospace applications, the failure transients related to major fault modes have to be characterised and analysed. By focusing the attention to jamming faults, a detailed nonlinear model of the actuator is developed from physical first principles and experimentally validated in both time and frequency domains for normal condition and with different types of jamming. The validated model is then used to design the condition-monitoring algorithms and to characterize the system failure transient, by simulating mechanical blocks in different locations of the transmission. The operability after the fault, obtained via fault-tolerant control strategy and position regulator reconfiguration, is also verified, by highlighting and discussing possible enhancements and criticalities.
The work deals with the model-based characterization of the failure transients of a fail-safe rotary EMA developed by Umbragroup (Italy) for the flap movables of the RACER helicopter-plane by Airbus Helicopters (France). Since the reference application requires quasi-static position-tracking with high disturbance-rejection capability, the attention is focused on control hardover faults which determine an actuator runaway from the commanded setpoint. To perform the study, a high-fidelity nonlinear model of the EMA is developed from physical first principles and the main features of health-monitoring and closed-loop control functions (integrating the conventional nested loops architecture with a deformation feedback loop enhancing the actuator stiffness) are presented. The EMA model is then validated with experiments by identifying its parameters by ad-hoc tests. Simulation results are finally proposed to characterize the failure transients in worst case scenarios by highlighting the importance of using a specifically designed back-electromotive damper circuitry into the EMA power electronics to limit the position deviation after the fault detection.
Clean aviation is a term that have been used more and more for some years now, more than a simple term is a mission prosecutable with More Electric Aircraft and All Electric Aircraft for greenhouse gas reduction. Electromechanical actuators represent key components for the replacement of actual pneumatic and hydraulic actuation systems, but the reliability is an important factor to take in account. In this paper an innovative and promising architecture of fault tolerant electromechanical actuator and the design process of electric motors for landing gear actuators for a small aircraft is presented.
This paper describes the analysis and design of an Electromechanical Actuator (EMA) that have been developed to open and close a gate valve for oil and gas applications. The rotating permanent magnet (PM) synchronous motor is integrated with the mechanical components in a rotating-ball nut architecture to minimize the total length and envelope of the actuator. The motion trajectory fits the classical profile, with high-torque at low-speed which is typical for gate valve operation. A comprehensive design methodology, which embraces both the electromagnetic and mechanical design, is described. Nonlinear electromagnetic and structural finiteelement analysis methods are employed to aid in the final design process. A prototype has been manufactured utilizing the design data of the optimization procedure. Test results confirm our hypothesis and calculations for the performance of the system.
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