Electromechanical Actuators Research Articles

Molecular-electromechanical system for unamplified detection of trace analytes in biofluids.

Biological research and diagnostic applications normally require analysis of trace analytes in biofluids. Although considerable advancements have been made in developing precise molecular assays, the trade-off between sensitivity and ability to resist non-specific adsorption remains a challenge. Here, we describe the implementation of a testing platform based on a molecular-electromechanical system (MolEMS) immobilized on graphene field-effect transistors. A MolEMS is a self-assembled DNA nanostructure, containing a stiff tetrahedral base and a flexible single-stranded DNA cantilever. Electromechanical actuation of the cantilever modulates sensing events close to the transistor channel, improving signal-transduction efficiency, while the stiff base prevents non-specific adsorption of background molecules present in biofluids. A MolEMS realizes unamplified detection of proteins, ions, small molecules and nucleic acids within minutes and has a limit of detection of several copies in 100 μl of testing solution, offering an assay methodology with wide-ranging applications. In this protocol, we provide step-by-step procedures for MolEMS design and assemblage, sensor manufacture and operation of a MolEMS in several applications. We also describe adaptations to construct a portable detection platform. It takes ~18 h to construct the device and ~4 min to finish the testing from sample addition to result.

Multi-physical Modeling of Launcher Electromechanical Actuators Accounting for Production Variability and Thermal Effects

Abstract With the trend towards reusable launchers, there is a need to develop health monitoring systems for electromechanical actuators (EMAs) performing nozzle orientation. To tune such a health monitoring system (HMS), data sets reproducing EMA operation in healthy and faulty modes are needed. Besides, effect of production variability and thermal dependency should also be accounted for. In this paper, a systematic approach to determine an EMA model from which appropriate data sets can be generated is presented. The focus is on mechanical faults such as high friction level that may lead to jamming and excessive backlash. From available experimental data sets recorded on a fleet of EMA, grey box identification is used to estimate the friction parameters including their confidence level for the different EMAs. Production variability is then characterized by showing that each parameter estimate is represented by a Gaussian distribution at a given temperature. Next thermal effects are accounted for through a Gaussian Process characterizing parameter variability w.r.t. temperature. Validation of the model is finally performed with EMA healthy operation data.

A CFD Modelling Approach for the Operation Analysis of an Exhaust Backpressure Valve Used in a Euro 6 Diesel Engine

Harvesting residual thermal energy from exhaust gases with thermoelectric generators is one of the paths that are currently being explored to achieve more sustainable and environmentally friendly means of transport. In some cases, thermoelectric generators are installed in a by-pass configuration to regulate the mass flow entering the thermoelectric generator. Some manufacturers are using throttle valves with electromechanical actuators and electronic control in the exhaust pipe to improve techniques for active control of pollutant emissions in reciprocating internal combustion engines, such as the exhaust gas recirculation. The above-mentioned circumstances have motivated the approach of this work: computational fluid dynamics (CFD) modelling of the operation of a throttle valve used for establishing adequate exhaust backpressure conditions to achieve the low pressure exhaust gas recirculation in Euro 6 engines. The aim of this model is to understand the flow control process with these types of valves in order to incorporate them in an exhaust system that will include two thermoelectric generators used to convert residual thermal energy into electrical energy. This work presents a computational model of the flow through the throttle valve under different temperatures and mass flow rates of the exhaust gas with different closing positions. For all cases, the values of the pressure drop were obtained. In all cases studied, the level of agreement between the modelled and experimental results exceeds 90%. The developed model has helped to propose a correlation to estimate the mass flow rate of exhaust gas from easily measurable quantities.

Fluoropolymer ferroelectrics: Multifunctional platform for polar-structured energy conversion.

Ferroelectric materials are currently some of the most widely applied material systems and are constantly generating improved functions with higher efficiencies. Advancements in poly(vinylidene fluoride) (PVDF)-based polymer ferroelectrics provide flexural, coupling-efficient, and multifunctional material platforms for applications that demand portable, lightweight, wearable, and durable features. We highlight the recent advances in fluoropolymer ferroelectrics, their energetic cross-coupling effects, and emerging technologies, including wearable, highly efficient electromechanical actuators and sensors, electrocaloric refrigeration, and dielectric devices. These developments reveal that the molecular and nanostructure manipulations of the polarization-field interactions, through facile defect biasing, could introduce enhancements in the physical effects that would enable the realization of multisensory and multifunctional wearables for the emerging immersive virtual world and smart systems for a sustainable future.

Functional Materials Made by Combining Hydrogels (Cross-Linked Polyacrylamides) and Conducting Polymers (Polyanilines)-A Critical Review.

Hydrogels made of cross-linked polyacrlyamides (cPAM) and conducting materials made of polyanilines (PANIs) are both the most widely used materials in each category. This is due to their accessible monomers, easy synthesis and excellent properties. Therefore, the combination of these materials produces composites which show enhanced properties and also synergy between the cPAM properties (e.g., elasticity) and those of PANIs (e.g., conductivity). The most common way to produce the composites is to form the gel by radical polymerization (usually by redox initiators) then incorporate the PANIs into the network by oxidative polymerization of anilines. It is often claimed that the product is a semi-interpenetrated network (s-IPN) made of linear PANIs penetrating the cPAM network. However, there is evidence that the nanopores of the hydrogel become filled with PANIs nanoparticles, producing a composite. On the other hand, swelling the cPAM in true solutions of PANIs macromolecules renders s-IPN with different properties. Technological applications of the composites have been developed, such as photothermal (PTA)/electromechanical actuators, supercapacitors, movement/pressure sensors, etc. PTA devices rely on the absorption of electromagnetic radiation (light, microwaves, radiofrequency) by PANIs, which heats up the composite, triggering the phase transition of a thermosensitive cPAM. Therefore, the synergy of properties of both polymers is beneficial.

Fault detection and isolation of electromechanical actuator based on SAE-BiLSTM

The control technology of electromechanical actuator(EMA) and its fault diagnosis is one of the key problems of multi-electric aircraft study. The method based on deep learning is used to diagnose and isolate the classic faults of EMA. The simulation model of EMA is modeling according to the working principle and control law. Four typical faults of EMA are studied,including return channel jam, spall, motor fault, and position sensor fault. Sparse Auto Encoder (SAE) algorithm can perform adaptive extraction of sensor data, which preserves dimensionality reduction and compression while preserving important features. Bidirectional Long Short Term Memory (BiLSTM) neural network is used to effectively process the time series data, which considering both past and future data during the fault diagnosis process. The established EMA model is simulated to obtain normal and faulty data sets, which are used to train the network by SAE-BiLSTM algorithm, and then the trained network is used for online fault diagnosis. After the experiment, SAE-BiLSTM algorithm can well complete the EMA fault detection and isolation.

Fast Calculation of Strand Eddy Current Loss in Inverter-Fed Electrical Machines

This paper investigates the complex the slot leakage magnetic field and the strand eddy current loss in windings of inverter-fed electrical machines. It shows that the magnetic saturation and the pulsewidth modulation (PWM) harmonics could have a significant influence on the slot leakage magnetic field, thus may influence the eddy current loss. To consider these effects while reducing the computation burden, a semi-analytical strand eddy current loss calculation method is proposed based on the slot leakage field calculation by 2D magnetostatic finite element method (FEM) and a 2-D analytical high-frequency eddy current loss expression. The frozen differential permeability method (FDPM) and the linear time-harmonics FEM are used to fast calculate the PWM-induced slot leakage field with the magnetic saturation considered. Besides, a conductor position model is used to extract the conductor coordinates and leakage field information for calculating the eddy current loss. The proposed method is implemented and experimentally validated on a surface-mounted permanent magnet (SPM) electro-mechanical actuator (EMA) fed by a PWM inverter for aircraft application. It shows high calculation accuracy and fast calculation speed, which is suitable for motor-inverter system design and optimization.

Electromechanical Actuator Servo Control Technology Based on Active Disturbance Rejection Control

Electromechanical actuators (EMA) are becoming more and more widely used. As the core technology of EMA, servo control technology determines their performance. In this paper, an active disturbance rejection control (ADRC) method with an improved extended state observer (ESO) is proposed to design a cascade controller of EMA based on permanent magnet synchronous motor (PMSM). The mathematical model of PMSM in a two-phase rotating coordinate system is established, then it is decoupled by an id=0 current control method to realize the vector control of the motor. In a three closed-loop vector control system, a PID controller including current loop, speed loop and position loop is designed. To solve the problems caused by measurement noise, the filter link and system are modeled as a whole, and an improved ESO is constructed. On this basis, an ADRC controller of the speed loop and position loop of PMSM is designed and simulated based on Simulink. Based on the physical test platform, a load step test and load disturbance test of ADRC are completed. The results show that, in comparison to the PID method, the ADRC method shortens the response time by 25% on average, and reduces the overshoot by 60% on average. So, it can be concluded that ADRC has good static and dynamic performance, which has a good guiding role for engineering practice.

Investigations on MBSE modelling and dynamic performance assessment of an electrical trimmable horizontal stabilizer actuator

With the development of power-by-wire technology for more electric aircraft, the electro-mechanical actuator (EMA) has the advantages to replace the conventional hydraulic servo actuator in some aerospace flight controls. Conventional hydraulically powered trimmable horizontal stabilizer actuation (THSA) system is nowadays developed to be electrically supplied. Given their safety-criticality, no-back mechanism and redundant load paths are utilized to meet the flight control requirements. However, rare literatures have introduced these functions and addressed the virtual prototyping activities from system-level point of view. This paper proposed such a model of a THSA system with dual electric power sources and fault-tolerant mechanical load paths. The nonlinear effects of components are considered with realism, and system-level simulation test is conducted to support the model-based system engineering (MBSE) approach. The models are developed with a power view instead of a pure signal view. Focusing on the friction effect and compliance effect with backlash or preload, some improved and novel approaches are adopted for these crucial components and validated via experimental results. Meanwhile, the implemented system-level model enables injection of crucial faults. Finally, the simulation of the proposed model shows that it is an efficient resource to investigate the actuator’s dynamic performance, to virtually prove that the actuator meets the fail/safe constraint, and to demonstrate the soundness of the fault monitoring functions.

Design and Preliminary Performance Assessment of a PHM System for Electromechanical Flight Control Actuators

The evolution toward “more electric” aircraft has seen a decisive push in the last decade due to growing environmental concerns and the development of new market segments (flying taxis). Such a push has involved both the propulsion components and the aircraft systems, with the latter seeing a progressive trend in replacing traditional solutions based on hydraulic power with electrical or electromechanical devices. Flight Control Systems (FCSs) are one of the aircraft systems affected the most since the adoption of Electromechanical Actuators (EMAs) would provide several advantages over traditional electrohydraulic or mechanical solutions, but their application is still limited due to their sensitivity to certain single points of failure that can lead to mechanical jams. The development of an effective and reliable Prognostics and Health Management (PHM) system for EMAs could help in mitigating the risk of a sudden critical failure by properly recognizing and tracking the ongoing fault and anticipating its evolution, thus boosting the acceptance of EMAs as the primary flight-control actuators in commercial aircraft. The paper is focused on the results of the preliminary activities performed within the CleanSky 2/Astib research program, dedicated to the definition of the iron bird of a new regional-transport aircraft able to provide some prognostic capabilities and act as a technological demonstrator for new PHM strategies for EMAs employed in-flight control systems. The paper is organized as follows. At first, a proper introduction to the research program is provided, along with a brief description of the employed approach. Hence the simulation models adopted for the study are presented and used to build synthetic databases to inform the definition of the PHM algorithm. The prognostic framework is then presented, and a preliminary assessment of its expected performance is discussed.

Motion Synchronization Control for a Large Civil Aircraft’s Hybrid Actuation System Using Fuzzy Logic-Based Control Techniques

The motion synchronization of the hybrid actuation system (composed of a servo-hydraulic actuator and an electro-mechanical actuator) is very important for all applications, especially for civil aircraft. The current research presents a nested-loop control design technique to synchronize motion between two different actuators, such as a servo-hydraulic actuator (SHA) and an electro-mechanical actuator (EMA). The proposed strategy consists of a trajectory, an intelligent position controller (fuzzy logic-based controller), a feed-forward controller, and an intelligent force controller (fuzzy logic-based controller). Position, speed, and acceleration signals are produced by trajectory at a frequency that both SHA and EMA can follow. The SHA/EMA system’s position tracking performance is enhanced by the feed-forward controller and intelligent position controller working together, while the intelligent force tracking controller lowers the issue of force fighting by focusing on the rigid coupling effect. To verify the effectiveness of the proposed strategy, simulations are performed in the Matlab/Simulink environment. The result shows that the proposed intelligent control strategy not only reduces initial force fighting, but also improves load-rejection performance and output-trajectory tracking performance.

An exploratory architecture using data and knowledge to close the loop between design and Maintenance from a product quality perspective

Products for personalization require frequent dynamic interactions at all stages of the entire lifecycle. Based on this, the researchers have been studying closed-loop product lifecycle management. However, most of them often focus on the strategic and conceptual levels and ignore the technical details of implementation. From a product quality perspective, a three-tier architecture using data and knowledge to close the loop between design, operation, and maintenance (O&M) is proposed to deal with this problem. FMECA automation enabled by industrial knowledge graph and construction of Bayesian network for failure propagation is introduced in detail to enhance efficient integration of design and maintenance phases. A proof-of-concept simulation based on an electromechanical actuator validates the applicability and efficiency of the proposed method, showing a closed-loop optimization of design and O&M services. This article potentially enables manufacturers to implement the linkage of design and O&M service business.

A Model-Based Prognostic Framework for Electromechanical Actuators Based on Metaheuristic Algorithms

The deployment of electro-mechanical actuators plays an important role towards the adoption of the more electric aircraft (MEA) philosophy. On the other hand, a seamless substitution of EMAs, in place of more traditional hydraulic solutions, is still set back, due to the shortage of real-life and reliability data regarding their failure modes. One way to work around this problem is providing a capillary EMA prognostics and health management (PHM) system capable of recognizing failures before they actually undermine the ability of the safety-critical system to perform its functions. The aim of this work is the development of a model-based prognostic framework for PMSM-based EMAs leveraging a metaheuristic algorithm: the evolutionary (differential evolution (DE)) and swarm intelligence (particle swarm (PSO), grey wolf (GWO)) methods are considered. Several failures (dry friction, backlash, short circuit, eccentricity, and proportional gain) are simulated by a reference model, and then detected and identified by the envisioned prognostic method, which employs a low fidelity monitoring model. The paper findings are analysed, showing good results and proving that this strategy could be executed and integrated in more complex routines, supporting EMAs adoption, with positive impacts on system safety and reliability in the aerospace and industrial field.

Sensor design for saltwater ingress detection in high reliable all-electric deep sea actuators

Subsea oil and gas production relies on Xmas Trees which are mounted on boreholes. Xmas Trees are an arrangement of different valve types and sizes actuated by hydraulic, electro-mechanic or all-electric actuators. All these actuators sharing problems with saltwater ingress and the re-sulting increased wear. This paper investigates potential effects which can be measured after saltwater ingress. Extensive testing is executed and the investigated effects are used for novel sensor designs. These designs are evaluated regarding certain requirements and a resulting sen-sor design is proposed for industrialization. The resulting sensor can then be used to collect new important data to support optimal maintenance in the subsea industry.

Simulation and Analysis of Electro Mechanical Actuator with Position Control

In recent times, Electro-Mechanical Actuator (EMA) is widely employed in various aerospace applications
 because of its compactness, ease of maintenance, and cost efficiency. It attracts most of the researcher for simulation and performance analysis. It is very much important to study its control system behaviour. In general, EMA requires, three loop cascade control, but for aerospace application two loop cascade control is used for speed and position controls due to dynamic load changing requirement. Most research efforts on EMA system has used a transfer function model of all its subsystems. Nevertheless, this technique does not yield complete outcomes for analysing its performance. To analyse its performance and characteristics in dynamic condition, an experimental model is essential. In addition, this model needs to cater for analysing performance of different capacity EMA. The primary goal of this work is to simulate unique EMA model with position control using a practical data and analyse its performance. In this design, EMA is modelled by three-phase Brushless Direct Current (BLDC) motor, six-step commutation logic, a speed sensor (Tacho) and a position sensor using Linear Variable Differential Transformer (LVDT). Position and speed controls are handled by Proportional (P) and Proportional plus Integral (PI) controllers respectively. The process reaction curve method is used to tune the controllers. This tuning approach is adequate to enable accurate and robust speed and position control. This paper focus on the simulation and performance analysis of a practical EMA system with position and speed controls in matlab-simulink. The performance analysis results shows that simulated model characteristic is close to physical system and reliable.

Cost Analysis Investigation of Toothed Belt Driven Electromechanical and Pneumatic Long Stroke Actuators

Otomasyon çalışmalarında pnömatik sistemler yaygın olarak kullanılmakla birlikte günümüzde elektromekanik tahrikli sistemlerin kullanımının yaygınlaşmaya başladığı gözlemlenmektedir. Elektromekanik sistemlerin pek çok farklı çeşidi bulunmaktadır. Genellikle servo motorun kontrol edilmesi ile hareket aktarımı sağlanmakta, bilyalı vidalı mil, dişli kayış vb. sistem elemanları ile dönme hareketi doğrusal harekete çevrilmektedir. Kontrol edilebilirliklerinin kolay, konumlama hassasiyetlerinin yüksek olması, uzun yıllar boyunca bakım istememesi gibi avantajlarıyla beraber bu tip sistemlerin kullanıcı tarafından tercih edilmesindeki en büyük tereddüt ilk yatırım maliyetlerinin yüksek olması olarak görünmektedir. Ancak ürün seçiminde ilk yatırım maliyeti ön plana çıkarken enerji tüketimi, bakım gibi parametrelerin de değerlendirilmesinin gerekliliği genellikle ikinci planda kalmaktadır. Bu çalışmada uzun stroklu, milsiz silindirli pnömatik bir sistem ile dişli kayış tahrikli elektromekanik bir sistemin ilk yatırım, bakım ve kullanım ömrü boyunca öngörülen enerji tüketim maliyetleri farklı çalışma senaryoları ile incelenmiş ve karşılaştırmalı olarak değerlendirilmiştir. Yatay yönde hareket eden iki sistemde de eşdeğer yük, strok, yıllık çalışma süresi ve kullanım zamanı dikkate alınarak deneysel çalışmalar ve teorik hesaplamalar yapılarak değerlendirilmiştir. Servo motorun ilk yatırım maliyetinin, pnömatik sistemin besleme basıncının, çevrim sayısının, bekleme süresinin sistemlerin maliyetlendirilmesinde önemli ve dikkate alınması gereken kriterler olduğu görülmüştür.

Development and Study of an Electromechanical Actuator for the Rotary Diaphragms of a Cogeneration Turbine

Development and Study of an Electromechanical Actuator for the Rotary Diaphragms of a Cogeneration Turbine

Elastographic measurements on soft biological tissues using holographic imaging by Rayleigh wave tracing

Tissue elasticity is one of the significant diagnostic parameters to study disease progression in biological tissues. Elastography measurements hold strong potential for determining the mechanical properties of malignant tissues in clinical practice. Optical methods for quantifying the elastic properties have received the attention of both research and medical community. In the current work, we calculate the elastic modulus of tissue-mimicking phantoms and ex-vivo biological tissue using holographic imaging by tracing Rayleigh wave propagation on the tissue surface. Rayleigh waves produced by the electromechanical actuator over a set of excitation frequencies are imaged by an ultrafast camera. The phase map reconstruction of the Rayleigh wave is carried out using a phase-shifting algorithm and the distance-time slope method is analyzed to compute Rayleigh wave velocities. The elastic modulus calculated by holographic imaging is validated against the gold standard mechanical compressional testing data. The quantitative results obtained from this current optical system combining holographic imaging and Rayleigh wave tracing are highly effective in ex-vivo and in-vivo tissue characterization and carry high potential as a promising tool in clinical translations and commercial adaptations.

Electromechanical Actuators for Haptic Feedback with Fingertip Contact

Haptic technology that provides tactile sensation feedback by utilizing actuators to achieve the purpose of human–computer interaction is obtaining increasing applications in electronic devices. This review covers four kinds of electromechanical actuators useful for achieving haptic feedback: electromagnetic, electrostatic, piezoelectric, and electrostrictive actuators. The driving principles, working conditions, applicable scopes, and characteristics of the different actuators are fully compared. The designs and values of piezoelectric actuators to achieve sophisticated and high-definition haptic effect sensations are particularly highlighted. The current status and directions for future development of the different types of haptic actuators are discussed.

Source free unsupervised domain adaptation for electro-mechanical actuator fault diagnosis

A common necessity for prior unsupervised domain adaptation methods that can improve the domain adaptation in unlabeled target domain dataset is access to source domain dataset and target domain dataset simultaneously. However, data privacy makes it not always possible to access source domain dataset and target domain dataset in actual industrial equipment simultaneously, especially for aviation component like Electro-Mechanical Actuator (EMA) whose dataset are often not shareable due to the data copyright and confidentiality. To address this problem, this paper proposes a source free unsupervised domain adaptation framework for EMA fault diagnosis. The proposed framework is a combination of feature network and classifier. Firstly, source domain datasets are only applied to train a source model. Secondly, the well-trained source model is transferred to target domain and classifier is frozen based on source domain hypothesis. Thirdly, nearest centroid filtering is introduced to filter the reliable pseudo labels for unlabeled target domain dataset, and finally, supervised learning and pseudo label clustering are applied to fine-tune the transferred model. In comparison with several traditional unsupervised domain adaptation methods, case studies based on low- and high-frequency monitoring signals on EMA indicate the effectiveness of the proposed method.