Electromechanical Actuation System Research Articles

High Torque Density Permanent Magnet Brake

As the braking device of the aircraft electromechanical actuation system, the brake is a vital link in the aircraft attitude change or function adjustment. Among them, the permanent magnet brake has attracted extensive attention in the field of aerospace technology because of its advantages of low energy consumption and high reliability. At present, the domestic permanent magnet brake is heavy and the braking torque density is generally low, which limits its further development in the field of aerospace. In order to improve the braking torque density of permanent magnet brake, this paper proposes a research method of high torque density permanent magnet brake is proposed. By establishing the magnetic circuit structure of the permanent magnet brake, the relationship between the external characteristics of the permanent magnet brake and the design parameters is determined, and then the performance parameters of the permanent magnet brake are simulated and verified by using the finite element simulation software. Finally, through the physical test, the results show that this method can effectively improve the braking torque density.

Modelling of a direct‐driven electromechanical actuation system based on the Lagrange–Maxwell equation

This study proposes an integrated non-linear modelling method for an electromechanical actuation system directly driven by the switched reluctance motor (SDEMA). The mathematical model of the SDEMA system is established by energy analysis and calculation according to the proposed method, which omits the complex analysis of force or torque transmission in the cascade modelling method. By using the Lagrange–Maxwell equation and establishing the energy models of non-linear factors that include the friction, backlash, and flexibility, both the electromechanical coupling effects and the non-linear factors of the SDEMA system are considered simultaneously in the proposed method. To verify the feasibility and effectiveness of the proposed method, three modelling methods of the SDEMA system are comparatively studied through the simulations and experiments. The results of the simulations and experiments indicate that the proposed integrative non-linear model can reflect the dynamic performance of the SDEMA system more accurately.

Conceptual Design of Electromechanical Actuation Systems for Large-Sized Directional Control Valves

Increasing performance in modern hydraulics is achieved by a close investigation of possible enhancements of its components. Prior research has pointed out that electromechanical actuators can form suitable alternatives to hydraulically piloted control systems. Since the requirements at these actuation systems depend on the operating conditions of the system, each actuator can be optimized to the respective hydraulic system. Considering that many different conceptual designs are suitable, the phase of conceptual design plays a decisive role during the design process. Therefore, this paper focuses on the process of developing new conceptual designs for electromechanical valve actuation systems using the method of function structures. Aiming to identify special design features, which need to be considered during the design process of electromechanical actuation systems, an exemplary actuator was designed based on the derived function structure. To highlight the potential of function structures for the development of new electromechanical valve actuation systems, two principal concepts, which allow the reduction of the necessary forces, have been developed by extending the function structure. These concepts have been experimentally investigated to identify their advantages and disadvantages.

Development of dielectric elastomeric actuators for morphing wings

In the last decades, wing morphing structures have aroused great interest due to their capability to improve the aerodynamic efficiency of modern aircraft. DE actuators, also known as “artificial muscles” due to their ability to exhibit large actuation strains at high voltages, are suitable candidates for morphing applications. This paper focuses on the research and development of miniature dielectric elastomeric actuators for variable-thickness morphing wings. A conical elastomeric actuation configuration has been proposed, consisting of a VHB4910 dielectric membrane preloaded with a spring mechanism and constrained to a rigid circular ring. The mini-actuators are developed to be fixed in an actuation array, mounted to the wing skin. This new electromechanical actuation system is designed to be integrated on thin airfoil wings, where conventional morphing structures cannot be used, because of restricted mass and space requirements. By controlling the thickness distribution using the proposed actuators, we may be able to maintain and delay the location of the laminar-turbulent transit towards the trailing edge, promoting laminar flow over the wing surface. Experimental models and prototypes will be developed in the next phase of the research project for further investigations.

Analysis and Design of a Leading Edge with Morphing Capabilities for the Wing of a Regional Aircraft—Gapless Chord- and Camber-Increase for High-Lift Performance

In order to contribute to achieving noise and emission reduction goals, Fraunhofer and Airbus deal with the development of a morphing leading edge (MLE) as a high lift device for aircraft. Within the European research program “Clean Sky 2”, a morphing leading edge with gapless chord- and camber-increase for high-lift performance was developed. The MLE is able to morph into two different aerofoils—one for cruise and one for take-off/landing, the latter increasing lift and stall angle over the former. The shape flexibility is realised by a carbon fibre reinforced plastic (CFRP) skin optimised for bending and a sliding contact at the bottom. The material is selected in terms of type, thickness, and lay-up including ply-wise fibre orientation based on numerical simulation and material tests. The MLE is driven by an internal electromechanical actuation system. Load introduction into the skin is realised by span-wise stringers, which require specific stiffness and thermal expansion properties for this task. To avoid the penetration of a bird into the front spar of the wing in case of bird strike, a bird strike protection structure is proposed and analysed. In this paper, the designed MLE including aerodynamic properties, composite skin structure, actuation system, and bird strike behaviour is described and analysed.

자속 차폐벽을 갖는 선형 홀센서 BLDC 모터를 이용한 전기식 조종날개 구동장치의 위치 제어

In general, position sensor and velocity sensor are used to design robust controller of the electro-mechanical fin actuator system. However, the use of such a sensor causes problems such as an increase in cost, an additional space for mounting, and a decrease in system reliability due to a sensor failure. To overcome these problems, rotor position sensor of the BLDC motor was replaced with linear type Hall-effect sensor having a magnetic flux shielding wall from the latch type Hall-effect sensor. The conventional position sensor and velocity sensor were removed through a position and velocity implementation algorithm using the analog output of the linear type Hall-effect sensor. In order to prove the validity of the proposed method, various comparison tests were performed with the existing position/velocity sensors. As a result of the test, the method proposed in this paper can obtain the position response similar to the case of applying the conventional position/velocity sensor.

Friction Compensation Control of Electromechanical Actuator Based on Neural Network Adaptive Sliding Mode.

In this paper, a radial basis neural network adaptive sliding mode controller (RBF−NN ASMC) for nonlinear electromechanical actuator systems is proposed. The radial basis function neural network (RBF−NN) control algorithm is used to compensate for the friction disturbance torque in the electromechanical actuator system. An adaptive law was used to adjust the weights of the neural network to achieve real−time compensation of friction. The sliding mode controller is designed to suppress the model uncertainty and external disturbance effects of the electromechanical actuator system. The stability of the RBF−NN ASMC is analyzed by Lyapunov’s stability theory, and the effectiveness of this method is verified by simulation. The results show that the control strategy not only has a better compensation effect on friction but also has better anti−interference ability, which makes the electromechanical actuator system have better steady−state and dynamic performance.

Chattering Suppression Fast Terminal Sliding Mode Control for Aircraft EMA Braking System

The performance of the electromechanical actuator (EMA) in the aircraft braking system suffers from the system’s nonlinear characteristics, whereas the robust control can contribute to the improvement of tracking precision in its servo system. In this article, a chattering suppression fast terminal sliding mode (FTSM) control strategy with an embedded nonlinear disturbance observer (NDO) is proposed for the EMA braking system, which can retain the fast convergence characteristic of the classical FTSM and guarantee the system converges to equilibrium point timely. Moreover, the singularity problem of the classical FTSM control is resolved through the well-designed sliding mode manifold. The NDO is designed to estimate the uncertain factors online, including time-varying parameters, external disturbance, and unmolded dynamics of the EMA system. By applying the compensation terms into the control law, the proposed control strategy can alleviate the chattering problem and improve system stability. To verify the performance of the proposed control strategy for EMA, wheel braking tests are conducted under various conditions regarding the type of runway and failure cases. The results indicate that the proposed control strategy can guarantee the servo performance, the control precision, and the response speed of the EMA servo system.

Design of a morphing leading edge as a high lift device for a regional aircraft

Morphing technologies can provide a significant contribution to reduction of noise and fuel consumption for future aircraft. In the framework of the European Aviation research programme Clean Sky 2, a design of a morphing leading edge was developed, which allows the simultaneous increase of wing chord and camber to adapt the airfoil to different airspeed conditions. The final design has a sliding contact at the bottom, whereas the upper surface is continuous with variable camber. In contrast to classical high lift devices, the lift coefficient can be increased without adding sources for turbulences at the upper wing surface. CFD analyses have been performed in order to quantify the aerodynamic performance of the designed morphing leading edge. Furthermore, a design concept both for the skin and for the actuation system is presented. The skin is designed using carbon fiber reinforced plastics (CFRP). In order to achieve both the required stiffness and flexibility, a customized non-constant layup is developed. Its feasibility for the high deformations during morphing is demonstrated by means of both numerical analysis and experimental validation. The electro-mechanical actuation system is designed to completely fit inside the morphing leading edge while still considering space for other subsystems. Besides the space requirements also weight, mountability and bird strike aspects are taken into account. Altogether, for the overall design of a morphing system is presented in this paper, various design challenges are highlighted and appropriate solutions for these challenges are discussed.

Fuzzy pid control of electromechanical actuator system

In order to meet the needs of modern high-performance aircraft, the fuzzy PID control strategy was used to design the electromechanical actuator control system. This control strategy combines the advantages of fuzzy control and PID control, and has better adaptability to time-varying complex systems. The electromechanical actuator control system adopted the three-loop structure, and current loop, speed loop and position loop were built on the platform of MATLAB / Simulink. Considering that the discrete universe fuzzy PID control algorithm has good real-time performance with small online computation, the fuzzy PID controller in discrete universe was designed in the position loop and the system was simulated. The simulation results show that the dynamic and steady performance of discrete universe fuzzy PID control is better than that of traditional PID control, and it is more suitable for electromechanical actuator system.

Two degree of freedom robust data-driven fixed-order controller synthesis using convex optimization

Improvement of precise reference tracking performance of positioning systems is one of the essential objectives in feedback control design process. However, since the robustness of the feedback control system normally limits the fine positioning capacity, improvement in reference tracking performance with the desired robustness is difficult to be achieved. This paper proposes a new data-driven approach based on convex optimization to design two degree of freedom robust fixed-order H∞ controller for reference tracking. Linear time-invariant systems represented by non-parametric frequency domain data are considered. A semi-definite programming algorithm is employed to compute an optimal uncertainty model and the corresponding nominal model. Then, a novel sufficient robust performance condition is developed using Nyquist stability theorem and μ-synthesis methods for feedforward control systems. The proposed method allows formulating closed-loop model matching objective and robust performance conditions by convex functions. In addition, the presented two degree of freedom robust data-driven fixed-order controller design algorithm also can be directly applied to time-delay systems without any approximation and conservatism. The theoretical design approach is experimentally verified on position control of an electromechanical control actuation system of an air vehicle. To improve the positioning accuracy of the actuation system, the full-closed loop feedback structure is considered. Obtained experimental results verify the usefulness and efficiency of the proposed approach.

Filter Design and Optimization of Electromechanical Actuation Systems Using Search and Surrogate Algorithms for More-Electric Aircraft Applications

In this article, the dc filter design and optimization problem is studied for dc electrical power distribution systems onboard more-electric aircraft. Component sizing models are built to serve as the basis of the optimization whose objectives are mass and power loss of this filter. A categorization strategy of search and surrogate algorithms is proposed and used for the target multiobjective optimization problem (MOOP). A genetic algorithm is utilized as a search algorithm to identify potential best solutions based on a set of filter sizing functions (subject to constraints). In addition, two machine learning (ML) algorithms are considered as surrogate algorithms to address the same optimization problem. In the ML training process, a constraint violation model is applied since there are various constraints in optimization, and this kind of classification model is relatively difficult to train. A support vector machine is applied for the constraint violation model; after that, two artificial neural networks are trained as the final surrogate model for mapping design variables to filter performance. To address these issues, a novel category of search and surrogate algorithms is proposed. Both algorithms are explored to solve the filter MOOP, and their optimization results are compared at the end.

Friction Torque Analysis of Planetary Roller Screw Mechanism in Roller Jamming

The load distribution model of the planetary roller screw mechanism (PRSM) is established on the basis of Hertz contact theory. The objective is to obtain a friction torque model of the PRSM in roller jamming. An example is provided to calculate the friction torque of the PRSM in roller jamming. Thereafter, the transmission efficiency is calculated. A static structural analysis is performed using the finite element method to estimate the contact stress between the threads of the PRSM components. Computational results indirectly reveal that roller jamming exerts considerable influence on the friction torque of the PRSM. Results show that the friction torque of the planetary roller screw increases when the roller is jammed and the wear of the parts is accelerated. This condition leads to structural failure. The results of this study can serve as a foundation for electromechanical actuation systems, which can be useful in designing antijamming systems for safety-critical aircraft applications.

Experimental research of dynamic characteristics of electro-backup hydraulic actuator at the load test-rig of flight control systems

The trend in aircraft systems development to overall electrification includes electrification of flight control actuation system. Generally, there’re two main technologies of «electrical» actuation, which use the power of on-board electrical system to move the aerodynamic surfaces. These technologies are electro-hydrostatic (EHA) and electromechanical (EMA) actuation systems. This paper describes the results of the dynamic testing of electro-backup hydraulic actuator (EBHA), which is one of the possible solutions for actuation systems of the next-generation flying vehicles.

Design of a High-Force Electromechanical Actuator for Electrically Driven Lathe Machine

This article proposes the design and driving mechanism of a single drive motor integrated electromechanical actuator system for the application in computer numerical control (CNC) lathe machines. The electromechanical actuator is designed in such a way that it can replace the conventionally used hydraulically powered headstocks of the lathe machine. To achieve a drawbar thrust of 50 kN and a spindle speed of 4000 r/m, a detailed design with an explanation of different internal parts of the electromechanical actuator is presented. The production ready model was simulated to select the safety factor of the whole system and to enquire the amount of deformation when 50 kN thurst is generated. A prototype is manufactured based on the analysis model and is tested for different modes of operation. The experimental results validate the capability of the electromechanical actuator to produce the require drawbar thrust of 50 kN and spindle speed of 4000 r/m.

A Position Synchronization Control for Dual Redundant Electro-mechanical Actuation in Flight Control System

The paper develops a position synchronization controller for a new active/active dual redundant electro-mechanical actuation system and designs a test platform to validate the performance of the controller. The mathematic models of the position synchronization system are firstly built based on the schematic of the active/active dual redundant electro-mechanical actuation system. The position controller for DEMA and GEMA of is developed based on the velocity and acceleration feed forward and traditional PID theory. A series of motion experiments are carried out to verify the effectiveness of the controller design for active/active dual redundant electro-mechanical actuation system. The experiments results show that the position controllers designed for either DEMA or GEMA are satisfied, the biggest following error is not more than 0.1mm. And the synchronous motion tests show that the PI plus Output Saturation feedback position synchronization control can reduce more than 30 percent synchronous position errors. Furthermore, the tests of position synchronization show that EMA stiffness has a big influence on the synchronous precision. The new position synchronization controller designed based on the accurate system model and actual system parameters can better achieve the position synchronization requirements of the dual redundant EMA system, which makes good sense for redundant systems.

Robust output feedback controller with high-gain observer for automatic clutch

Abstract Precise and stable position control is critical in automatic clutch system, which is a challenging issue because of its nonlinear characteristics, uncertainties of parameters and disturbances, and lack of all-state sensors. Therefore, a novel robust output feedback control method is proposed in this paper to deal with the nonlinearities, uncertainties and modeling errors. First, an electromechanical dry clutch actuator system is formulated by theoretical analysis combined with experimental data. Then, a robust controller is designed, including the recursive control law calculation and a high-gain observer based on output feedback to estimate the unmeasured states. Next, simulations are carried out to verify the effectiveness of proposed method. Finally, experiments are conducted on a hybrid electric powertrain bench and the results show that the proposed method has a satisfactory performance.

Data-driven fixed-order H∞ controller synthesis in frequency domain: Closed-loop system approach

Control performance degradation is inevitable due to unmodeled dynamics and the requirement of using small set of parameters in parametric models. In this study, a frequency domain data-driven fixed-order [Formula: see text] controller synthesis approach is introduced to solve above mentioned problem for linear systems. In our approach, the generalized plant is identified by using experimental data obtained from closed-loop tests. The transfer function of the structured [Formula: see text] controller is synthesized by using only the frequency response of the plant without the need of a parametric model. The presented approach is verified experimentally for position control of an electromechanical control actuation system with proportional-derivative (PD) type controller.

Improved Safety Analysis Integration in a Systems Engineering Approach

The goal of the paper is the integration of safety analysis in a model-based systems engineering approach to ensure consistency between system design and safety artifacts. This integration permits the continuous improvement of the structure and behavior of the system. It also reduces system development time and prevents late detection of errors. To reach this purpose, the SafeSysE methodology is extended. In SafeSysE, a preliminary Failure Mode and Effects Analysis (FMEA) is automatically generated from a SysML model, and this FMEA is then completed by the safety expert but no further development was proposed. The contribution of this paper is to suggest recommendations based on the FMEA analysis in order to enhance the system design and make it comply with safety requirements. First, an updated system structure that may contain redundancy is proposed. Then, a redundancy profile is used to enrich the system model with redundancy information, which will allow the generation of a dynamic fault tree considering the system behavior. Finally, the generated dynamic fault tree should be analyzed in order to create a state machine diagram that describes the behavior of the system. The created state machine with an internal block diagram will help the system designers to better understand the system dysfunctions by simulating the system. The proposed methodology is applied to an Electro-Mechanical Actuator system which is used in the aeronautics domain.

10,000 lbf-in급 힌지라인 이중화 전기식 구동장치 설계 및 성능평가

항공기용 전기식 구동장치는 유압식 구동장치에 비해 소형/경량화에 유리하고, 힌지라인 형태의 구동장치는 공기저항이 작고 스텔스 등의 특수 목적에 적합한 특징을 가지고 있다. 본 논문에서는 10,000 lbf-in급 힌지라인 이중화 전기식 구동장치의 동작성능시험을 위한 시스템 설계 내용을 기술하였다. 영구자석전동기의 자속 기준 제어와 이중화 구동기의 torque fighting을 고려한 제어기를 설계하고, 구동장치 시스템 모델을 수립하여 성능 시뮬레이션을 수행하였다. 성능시험을 수행하여 시뮬레이션 결과와 비교하였으며 목표성능 만족여부를 확인하였다.