Primary Flight Control Research Articles

An optical red green blue sensor for monitoring the degradation of magnetorheological fluids in flow-recirculating high-torque clutch actuators

The aerospace industry is gradually moving toward “more electric aircraft” to reduce its environmental footprint. Developing all-electric actuators brings a reliability challenge because conventional geared-motor actuators are susceptible to jamming failures from their metal-to-metal gear contacts. Magnetorheological clutch actuators solve this challenge using a layer of fluid to transmit torque and are not exposed to potential jam failures, making them particularly attractive for high reliability applications such as primary flight controls. A key challenge that must be addressed for a widespread deployment of the magnetorheological fluid technology in aerospace is the ability to monitor magnetorheological fluid condition while it degrades in operation. To date, no such efforts have been reported in the literature. Recent studies on magnetorheological fluid durability have shown that mixing the magnetorheological fluid using a magnetic screw pump principle can significantly increase the life of the fluid by up to 50%. This article presents the design, prototyping, and testing of a proof-of-concept magnetorheological fluid condition monitoring sensor, capitalizing on the flow-recirculating properties of magnetic screw magnetorheological clutches to continuously provide a well-mixed and homogeneous fluid sample to the sensor. The proposed sensing principle uses optical red green blue sensor placed in the fluid circulation path to measure the fluid color during degradation. The sensor has been tested up to fluid failure on a high-torque (60 N m) magnetorheological clutch mounted on a fully instrumented durability test bench. Tests have been performed with two types of fluid: a commercially available fluid, the Lord 140CG, and a homemade fluid based on perfluoropolyether oil, the GPL-103. Results with the Lord fluid demonstrate a strong correlation between the decrease in torque-to-current performance with fluid brightness. The average of three aging tests on Lord 140CG fluid show a 12% ± 1% decrease in brightness at end-of-life regardless of operating conditions such as torque, shear rate, and dissipated power. These results suggest that, for the Lord 140CG fluid, brightness is directly linked to the fluid degradation state and independent of operating conditions, which makes it a more accurate metric to quantify durability than life dissipated energy since the latter can vary significantly depending on operating conditions. Tests made with the GPL-103 based fluid did not show such a strong correlation, which means that optical sensing of magnetorheological fluid condition must be carefully calibrated for each individual fluid and clutch design. Results from this study suggest that optical sensing is a relevant method to measure the magnetorheological fluid condition in flow-recirculating clutches.

Troubleshooting and Fault Analysis of Initial Built-In Test Interruption of Civil Aircraft Primary Flight Control System

Currently, there are no flight control alarms or CMS fault information triggered when initial Built-In Test is interrupted for primary flight control system, in fact, only “TEST ABORTED” displayed for the “TEST STATUS” on the CMS, which brings some difficulties to the Built-In Test interruption troubleshooting. A Built-In Test interrupt troubleshooting methodology is proposed in this paper based on fault tree analysis.

Toward a Robust Design of an Aileron Electromechanical Actuator: Sensitivity Analysis and Parametric Tolerancing Using a Variational Approach

For a mechatronic system, the lack of robustness is mainly due to an ignorance of variability, which is unavoidable in every designed system at all stages of system development and during its life cycle. In fact, the inherent imperfections of manufacturing processes and operational variations such as material wear or multiphysical effects (thermal, vibrations, etc.) involve parametric variations, which can degrade the proper system function. To ensure a high level of quality and to improve design robustness, the deviations between actual and target definition should be restricted by specified tolerances. Moreover, it is important to understand the relationship between parameter deviations and system behavior. Thus, in this article, a variational approach is proposed to identify performance sensitivity to parameter deviations in a mechatronic system and to determine influential parameters that affect significantly the proper functioning of the system and its behavior. Furthermore, this approach is used to specify the admissible parameter deviations for which the given specifications can be guaranteed. The complete approach is applied to an example in the aeronautic field: an electromechanical actuator driving an aircraft primary flight control surface (aileron).

A magnetic screw pump for magnetorheological clutch durability enhancement

Magnetorheological clutches have great potential for demanding applications such as powertrains and aircraft primary flight controls. However, in such high-power applications (>1 kW), durability is a challenge because of the continuous slippage at the clutch shear interface. To improve durability, this research studies the potential of using a magnetic screw pump to promote fluid mixing within a magnetorheological clutch. The screw flights are made of magnetorheological fluid formed by the concentration of the magnetic field lines around helical grooves machined into the shear interface (drum) of the clutch. While the magnetic pump does not display a typical screw pump behavior, a semi-empirical yield screw pump model is proposed to better understand the macroscopic behavior. Experimental flow characterization results show that the pressure–flow relation is significantly affected by the number of grooves, magnetic field intensity, and rotational speed. For a clutch containing 50 mL of magnetorheological fluid, maximum flow rates of up to 25 mL/min and a maximum pressure of 150 kPa are achieved. Finally, durability test results show that the magnetic screw pump can increase durability by up to 42% when compared to a standard magnetorheological clutch, confirming that such a device is a viable solution for promoting durability.

Variational approach for robust design and sensitivity analysis of mechatronic systems

ABSTRACTThe behavior of mechatronics systems has a very complex inter-relation between several components, depending on the magnitudes of their parameters and variables. To ensure a certain level of quality and to improve design robustness, the deviations between actual and target definition should be restricted by specified tolerances. The upper and lower limits of these values must be wisely determined. Moreover, the deviation margin of variables should be controlled to evaluate system performance in regard to the specifications, requirements and user needs. In this paper, a variational approach is used to evaluate the impact of parameters’ deviation on the system behavior. It consists of defining the relationship between parameters’ tolerances and variables’ fluctuations. This method helps designers to identify the sensitivity of system performances to parameter variations and can, thus, help the designer to attain a compromise between system performance and manufacturing cost in mechatronic systems. The proposed methodology is explained with an example in the aeronautic field, namely an electromechanical actuator driving an aileron which is an aircraft primary flight control surface. This method is general and it can be adapted for other mechatronic systems. The results show that the proposed method affords a new way for determining mechatronic tolerances.

A Machine Learning Enabled Multi-Fidelity Platform for the Integrated Design of Aircraft Systems

Abstract The push toward reducing the aircraft development cycle time motivates the development of collaborative frameworks that enable the more integrated design of aircraft and their systems. The ModellIng and Simulation tools for Systems IntegratiON on Aircraft (MISSION) project aims to develop an integrated modelling and simulation framework. This paper focuses on some recent advancements in the MISSION project and presents a design framework that combines a filtering process to down-select feasible architectures, a modeling platform that simulates the power system of the aircraft, and a machine learning-based clustering and optimization module. This framework enables the designer to prioritize different designs and offers traceability on the optimal choices. In addition, it enables the integration of models at multiple levels of fidelity depending on the size of the design space and the accuracy required. It is demonstrated for the electrification of the Primary Flight Control System (PFCS) and the landing gear braking system using different electric actuation technologies. The performance of different architectures is analyzed with respect to key performance indicators (fuel burn, weight, power). The optimization process benefits from a data-driven localization step to identify sets of similar architectures. The framework demonstrates the capability of optimizing across multiple, different system architectures in an efficient way that is scalable for larger design spaces and larger dimensionality problems.

Design of Flight Control System Mechanism for National Glider GL-1

This paper reports a design of flight control system mechanism which will be implemented in the national glider GL-1. The flight control system in the glider GL-1 includes the following control surfaces: elevator, ailerons, and rudder for primary flight control system as well as flaps and airbrakes for secondary one. In designing the components of flight control system, selections of type, material, and dimension of components are based on loads computation as well as benchmarking to some modern gliders. Mechanism and kinematics of flight control system are designed to comply with regulation as well as space availability. Fully-mechanical flight control system is selected for the aircraft since the aerodynamic forces acting on the glider are not excessive. The aircraft uses a centre-stick as manipulator for pilot to control longitudinal and lateral movements, which is linked to elevator and ailerons by push-pull rods with coupled mechanism. Meanwhile, for directional control, an adjustable pedal is used. The pedal is linked to the rudder by tension cables. Plain flaps and flat-plat panel airbrakes are selected as flap and airbrake types in this glider. The flaps and airbrakes are controlled by mechanical levers, which are linked by push-pull rods.

High redundancy electromechanical actuator for thrust vector control of a launch vehicle

Purpose The purpose of this paper is to design an electromechanical actuator which can inherently tolerate a stuck or loose failure without any need for fault detection isolation and reconfiguration. Design/methodology/approach Generalized design methodology for a thrust vector control application is adopted to reduce the design iterations during the initial stages of the design. An optimum ball screw pitch is selected to minimize the motor sizing and maximize the load acceleration. Findings A high redundancy electromechanical actuator for thrust vector control has lower self-inertia and higher reliability than a direct drive simplex configuration. This configuration is a feasible solution for thrust vector control application because it offers a more acceptable and graceful degradation than a complete failure. Research limitations/implications Future work will include testing on actual hardware to study the transient disturbances caused by a fault and their effect on launch vehicle dynamics. Practical implications High redundancy electromechanical actuator concept can be extended to similar applications such as solid motor nozzle in satellite launch vehicles and primary flight control system in aircraft. Social implications High redundancy actuators can be useful in safety critical applications involving human beings. It can also reduce the machine downtime in industrial process automation. Originality/value The jam tolerant electromechanical actuator proposed for the launch vehicle application has a unique configuration which does not require a complex fault detection isolation and reconfiguration logic in the controller. This enhances the system reliability and allows a simplex controller having a lower cost.

Magnetically Geared Pseudo Direct Drive for Safety Critical Applications

This paper presents an investigation into the electromagnetic design and performance of a fault-tolerant (FT) magnetically geared pseudo-direct-drive (PDD) electrical machine for primary flight control surface electromechanical actuation. It is shown that a large number of combinations of high-speed rotor pole pairs, pole-piece numbers, and stator slot numbers exist, for which a duplex three-phase FT configuration can be realized. Furthermore, in addition to facilitating a lower mass solution, it is also shown that a PDD presents a significantly lower inertia referred to the screw when compared to direct-drive or mechanically geared motor solutions. The findings are validated on a prototype PDD, which has been designed and built to meet the requirements of a primary control surface electromechanical actuator.

Experimental Development of a Health Monitoring Method for Electro-Mechanical Actuators of Flight Control Primary Surfaces in More Electric Aircrafts

This paper presents a health monitoring approach for Electro-Mechanical Actuators (EMA). We define four different indicators to continuously evaluate the health state of the system. The four indicators are computed by leveraging the output from a Statistical Process Monitoring (SPM) method based on multivariate statistics, such as the Hotelling's T <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> statistic and the Q statistic. SPM approaches give a dichotomous answer, i.e. the presence/absence of a fault. In this work, we propose four ways to compute a continuous indicator starting from the discrete SPM output, that is better suited for health monitoring. We test the approach using a dataset collected from a large experimental campaign on a 1:1 scale EMA for primary flight controls of small aircrafts, that led to EMA failure. Results show the effectiveness of the method.

Metode Balancing Jig Procedure pada Tab Elevator Pesawat Boeing 737-800 untuk Mengurangi Dampak Flutter

Primary flight control pada pesawat udara terdiri dari aileron, rudder dan elevator, Secondary flight control terdiri dari flaps, slats, spoiler dan trim tab. Pesawat sebelum terbang harus dipastikan semua flight control dalam keadaan balance. Jika tidak, maka flutter akan terjadi ketika pesawat tersebut mengudara. Flutter adalah salah satu fenomena aeroelastisitas, yaitu fenomena getaran yang mengakibatkan sayap pesawat terbang “mengepak” seperti sayap burung. Hal ini diakibatkan karena kombinasi efek kekakuan struktur sayap, aerodinamika serta inersia (berat) dari struktur. Untuk menghindari terjadinya flutter harus dilakukan balancing flight control, salah satunya pada Tab Elevator. Tab elevator sering disebut dengan trim tab pada elevator. Trim Tab tersebut melekat pada elevator yang terletak pada horizontal stabilizer. Meskipun trim tab merupakan secondary flight control, harus tetap dipastikan balance. Cara balancing tab elevator adalah dengan metode jig procedure, dimana tab harus dilepas terlebih dahulu. Balance atau tidaknya tab elevator ditentukan dari nilai Tab Assembly Moment (TAM). Hasil yang didapat dari penelitian ini adalah 15.22 lbfinch dan tab dikatakan balance, karena menurut Structural Repair Manual (SRM) Boeing 737-800 range maksimal nilai TAM adalah 15.48 lbfinch. Jika pada penelitian didapatkan hasil lebih dari 15.48 lbfinch, maka tab harus dikembalikan ke paint shop untuk dilakukan pengelupasan beberapa lapisan catnya agar mengurangi beban tab tersebut. Apabila pengurangan beban pada tab tidak bisa dilakukan lagi, maka Tab tersebut dianggap reject (tidak layak) dan harus diganti dengan yang baru.

LA MECCANICA DELLE MACCHINE NELL’INNOVAZIONE DEI PRODOTTI E DEI PROCESSI

The present report highlights the current and future role of techniques and methodologies of the Mechanics of Machines, both in the design of devices and systems, and in the university training courses. The underlying theme of the presentation lays in the interpretation of the physical phenomenon which oversees the operation of the machines. This is the foundation allowing to define an input-output interaction between the physical quantities operating on the machine. The cause-effect relation offers the possibility to determine a set of analytical relations for the prediction of the operation of the machine and to simulate theoretical and / or numerical trends in time or frequency domain of the significant mechanical quantities. It is evident the magnitude of the physical phenomena that arise in the operation of a machine, resulting in a broad variety of related Mechanics of Machines topics: from the contact between bodies analysis to tribological aspects, from body geometry to kinematics, from the rigid to deformable body dynamics, from the interaction between mechanical bodies to manmachine interaction, from the kinematic and dynamic behavior of a mechanical system to its interface with the actuators, sensing and control, just to name some of them. It should also be considered that the interpretation of the physical phenomenon of organs of machines has to be supported by significant experimental campaigns, specifically reproduced in laboratory, or related to data from real applications in the different application domains. The evolution of Mechanics of Machines proved in the years to be able to respond to these two interacting and converging questions: on the one hand the need to identify analytical relations, possibly not based on sole mappings of data, but rather on representative analytical relations of physical quantities, and on the other hand, the need, even at the university level, to conduct appropriate laboratory test campaigns related to the real field operation of the machine. With reference to the first objective, the need to determine algorithms, typically non-linear, and the consequent simulations setups, has resulted in the passage of the Machine Mechanics from a theoretical subject, to a subject with strong computational valences creating tools for the prediction of the behavior of devices and systems, in relation to their diagnosis and health state. The second objective has required the achievement of competence also in the field of the test rigs, of sensing and measuring / data acquisition systems. The paper deals with the identification and the presentation of the different areas related to Machine Mechanics, exposing in a matrix the enabling technologies on the one hand and the application domains to which they apply in the other hand. The enabling technologies traditionally belong to the topics of kinematics, statics, dynamics (linear and nonlinear), to the interactions with the environment (force fields, interactions with fluids) and between surfaces (lubrication), control, automation and system identification, as well as to the study and identification of vibratory phenomena, vibro-acoustic and tribological ones, mechatronics, fluid-structure interactions, monitoring, diagnostics and prognostics of mechanical systems, fluid automation and robotics, fluidics and microfluidics, to the implementation of pneumatic, hydraulic, electric and non-conventional technologies, to environmentally friendly and renewable energy systems. The application domains relate to the mechanical systems, such as driving and operating machinery, mechanical devices, mechanisms, transmissions and drives, automatic and robotic, vehicles on road, rail, fixed wing and rotorcrafts, transportation and lifting systems, systems for the production of energy, the biomechanical systems. A summary of the ongoing activities in the different research groups of the Italian Universities is then presented, from which you can also highlight the methodology of the studies addressed, strongly aimed at a unifying approach through the use of fundamental methods of theoretical applied and experimental mechanics, with attention to environmental and energy sustainability, and significantly connected on one side with the state of international research, and on the other with the industrial and manufacturing reality of the country. At the end of the paper sectors of Machine Mechanics that in the opinion of the writer need to be investigated further are discussed. Some technological challenges, such as prognostic models applied to servo systems in primary flight controls for aircraft applications, are outlined. The state of the art in that domain highlights the contribution to the innovation of processes and products, challenge that need to go back to the inputoutput interactions at the base-mechanics layer. Without those aspects it is impossible to be able to predict the evolution of degradation in the actuation systems, and to determine the remaining life of a mechanical device.

Flight envelope expansion based on active mitigation of flutter via a V-stack piezoelectric actuator

The instability of the aircraft’s flexible control surfaces caused by uncontrolled vibrations represents a challenging issue of the aviation security. Flutter is a violent vibration whose amplitude grows strongly in a short time. Once the flutter is reached, the plane is destabilized and it can no longer be controlled. This paper proposes a specially designed demonstrator intended to extend the flight envelope by raising the speed limit at which the flutter occurs. The anti-flutter demonstrator is an intelligent airplane wing model made from a longeron covered by an aerodynamic layer. The wing has an aileron as a primary flight control surface, at one end, and a flange conceived to fix the wing in the aerodynamic tunnel, at the other end. The actuator consists in two V-shaped piezo stacks. The main advantage of the piezo actuator, the bandwidth (about 30 Hz), is exploited. The aero-elastic control is efficient if the deflection of the control surface is of a few degrees while the frequency is of at least 25-30 Hz. The control law is obtained through the receptance method of eigenvalues assignment using the on line input/output measured transfer function rather than the knowledge of system matrices.

Feasibility Study of a PHM System for Electro-hydraulic Servo-actuators for Primary Flight Controls

Electro-Hydraulic Servo-Actuators (EHSA) are by far the mostly used type of actuators in aircraft primary flight control systems. Though electrical actuation is been considered since long as a possible replacement of hydraulic actuation for aircraft systems, EHSAs are still the technology of choice in the primary flight control systems of new commercial aircrafts. Considering that 10 or more EHSAs are typically used in an aircraft flight control system, the development of an effective PHM system for this equipment could provide large benefits and be of great interest for the OEMs and for the air fleet operators.&#x0D; This paper presents the results of a feasibility study making up the first part of an ongoing research activity focused on the development of a PHM system for EHSAs used in fly-by-wire primary flight control systems and takes as a use case the primary flight control actuator of a wide body commercial aircraft. One of the key features of the research is the implementation of a PHM system without the addition of new sensors, taking advantage of the available signals. This offers the possibility of implementation of the PHM system on the existing platforms and not only as a proposition for new aircrafts designed with a complement of additional sensors. The enabling technologies for this PHM system borrow from the area of Bayesian estimation theory and specifically particle filtering and the information acquired from EHSA in-flight and during pre-flight check is processed by appropriate algorithms in order to obtain relevant features, detect the degradation and estimate the Remaining Useful Life (RUL). The results are evaluated through appropriate metrics in order to assess the performance and effectiveness of the implemented PHM.&#x0D; This paper describes the methodology of the feasibility study, which shows how the novel PHM technologies proposed for a PHM system for the EHSAs of primary flight control actuators can allow the migration from unscheduled / on-condition maintenance to condition based maintenance targeting the perceived objectives of the OEM and of the aircraft operator.

Enhanced Particle Filter framework for improved prognosis of electro-mechanical flight controls actuators

The technology of flight control actuators is at the forefront of the “more electric aircraft” research trend since its beginning, due to the several advantages that the introduction of Electro Mechanical Actuators (EMAs) would provide over the traditional hydraulic/mechanical solution for both primary and secondary flight control surfaces. However when compared to hydraulic actuators, technological barriers still persist for a wide adoption of EMAs especially when considering their sensitivity to certain single point of failures that can lead to mechanical jams, resulting in a reluctance to adopt EMAs for flight safety critical applications as solutions are heavy and costly (redundancy, fail safe behavior, etc.), thus creating difficulties for adoption and certification and impacts on costs. The development of an effective and reliable PHM system for EMAs could help mitigating the risk of a sudden critical failure by properly recognizing and tracking the ongoingfault and anticipating its evolution, and will offer a possible way contributing to the acceptance of EMAs as primary flight control actuators in commercial aircraft. The paper firstly presents an enhanced Particle Filter framework for improved prognosis, discussing its benefits and its implementation inside a general PHM framework developed for EMAs. Then, three significant examples of its application are provided relevant to an electrical and a mechanical fault of the EMA: degradation of the electric motor and backlash increase in the mechanical transmission due to the growing wear of its components. The positive results obtained from the application of the enhanced Particle Filtering framework to these faults provide good confidence on the possibility of extending it to other EMAs faults and to successfully implement this technique to EMAs for flight control actuators.

Prognostics of Onboard Electromechanical Actuators: a New Approach Based on Spectral Analysis Techniques

In the last years, the layout of servomechanisms used in the aeronautical field to actuate the flight controls has changed radically and, nowadays electromechanical actuators (EMAs) are increasingly replacing the older hydraulic powered actuator types. The definition of special monitoring procedures, based on the analysis of the system response and aiming to evaluate the evolution of faults, represents an important task of the modern system engineering taking into account that onboard actuators are typically safety critical items. The present paper proposes a new prognostic procedure centered on the characterization of the state of health of an EMA used in aircraft primary flight controls. This approach, based on the innovative use of a model-based fault detection and identification method (FDI), identifies the actuator actual state of wear of the actuator analyzing proper system operational parameters, able to put in evidence the corresponding degradation path, by means of a numerical algorithm based on spectral analysis techniques. The proposed FDI algorithm has been tested in case of EMA affected by two progressive failures (rotor static eccentricity and stator phase turn-to-turn short-circuit), showing an adequate robustness and a suitable ability to early identify EMA malfunctions with low risk of false alarms or missed failures.

Intelligent Diagnostics for Aircraft Hydraulic Equipment

In aviation industry, unscheduled maintenance costs may vary in a large range depending on several factors, such as specific aircraft system, operational environment and aircraft usage and maintenance policy. These costs will become more noteworthy in the next decade, due to the positive growing of worldwide fleet and the introduction of more technologically advanced aircraft. The new implemented technologies will bring new challenges in the Maintenance, Repair and Overhaul (MRO) companies, both because of the rising number of new technologies and high volume of well-established devices, such as Electro-Hydraulic Servo Actuators for primary flight control. Failures in aircraft hydraulic systems deeply influence the overall failure rate and so the relative maintenance costs. For this reason, overhaul procedures for these components still represents a profitable market share for all MRO stakeholders. Innovative solutions able to facilitate maintenance operations can lead to large cost savings. This paper proposes new methodologies and features of the Intelligent Diagnostic system which is being developed in partnership with Lufthansa Technik (LHT). The implementation of this innovative procedure is built on a set of failure detection algorithms, based on Machine Learning techniques. This development requires first to bring together the results from different parallel research activities: Identification of critical components from historical data; Designing and testing automatic and adaptable procedure for first faults detection; High-fidelity mathematical modeling of considered test units, for deeper physics analysis of possible failures; Implementation of Machine Learning reasoner, able to process experimental and simulated data.

A modelling framework to support power architecture trade-off studies for More-Electric Aircraft

Abstract This work presents a modelling framework to enable comparison and trade-off study of different aircraft system architectures. The framework integrates a computational module to select feasible architectures with a modelling platform that simulates the power generation, distribution and fuel consumption of the aircraft as well as system-level models for the system being evaluated. Its capabilities are demonstrated for the case of the electrification of the primary flight control system (PFCS) using different electric technologies (EHA, EMA) and different levels of electrification ranging from the conventional hydraulic to the all-electric. The performances of different architectures are analysed with respect to the change in the mechanical power extracted from the engine, the weight and the fuel burn of the aircraft. The framework demonstrates the capability of evaluating multiple, different, system architectures in a way that is scalable for different systems or different aircraft. It supports a designer evaluating the aircraft-level impact of their design choice at system-level, and it can aid in assessing technology options early in the design process.

Design of a five‐phase permanent‐magnet motor for the electric steering of an aircraft nose landing gear

Recently, there has been a growing interest in reducing the number or replacing the hydraulic/pneumatic actuators utilised on aircraft with electric actuators coupled to mechanical gears, which would improve the reliability and performance. This is involved in the concept of more electric aircraft. The electrification of actuators would affect the primary and secondary flight controls, as well as the movement of flight surfaces, retraction of the landing gear, and steering of the nose landing gear, which is also considered in this study. This study considers the design of a multiphase permanent-magnet (PM) motor to be utilised for the electric steering of a commercial aircraft nose landing gear. This multiphase motor would make it possible to achieve a highly reliable actuator and, coupled with a harmonic drive, avoid the use of a multi-motor configuration. Moreover, a multiphase motor would increase the power density and efficiency of the actuator, through improving the torque ripple. The performance variation due to temperature swings is considered, and a design procedure for the PM motor is described using the worse operation case for the electric actuator. The adequate performance of the designed motor and actuator is demonstrated by means of a finite element analysis.

Linear Extended State Observer-Based Motion Synchronization Control for Hybrid Actuation System of More Electric Aircraft.

Moving towards the more electric aircraft (MEA), a hybrid actuator configuration provides an opportunity to introduce electromechanical actuator (EMA) into primary flight control. In the hybrid actuation system (HAS), an electro-hydraulic servo actuator (EHSA) and an EMA operate on the same control surface. In order to solve force fighting problem in HAS, this paper proposes a novel linear extended state observer (LESO)-based motion synchronization control method. To cope with the problem of unavailability of the state signals required by the motion synchronization controller, LESO is designed for EHSA and EMA to observe the state variables. Based on the observed states of LESO, motion synchronization controllers could enable EHSA and EMA to simultaneously track the desired motion trajectories. Additionally, nonlinearities, uncertainties and unknown disturbances as well as the coupling term between EHSA and EMA can be estimated and compensated by using the extended state of the proposed LESO. Finally, comparative simulation results indicate that the proposed LESO-based motion synchronization controller could reduce significant force fighting between EHSA and EMA.