Actuators

Open AccessArticle

Increasing the Force Exertion of a Soft Actuator Using Externally Attachable Inter-Chamber Plates

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Attila Mészáros

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József Sárosi

Actuators 2023, 12(6), 222; https://doi.org/10.3390/act12060222 - 27 May 2023

Abstract

The application of soft actuators has become increasingly common in wearable devices. In this study, we investigated the force characteristics of soft actuators made entirely of elastic material, when equipped with solid external chamber plates of varying thickness that can be attached from [...] Read more.

The application of soft actuators has become increasingly common in wearable devices. In this study, we investigated the force characteristics of soft actuators made entirely of elastic material, when equipped with solid external chamber plates of varying thickness that can be attached from the outside. This study examines the effect of these plates on the force characteristics of a fully silicone-based fifteen-chamber soft actuator without any non-stretchable internal components. The parameters of the actuator were determined with consideration of wearable applications, such as rehabilitation devices and exoskeletons. The observed differences in the behavior of the actuator at various pressure levels and plate thicknesses were measured. Furthermore, the effect of the externally inserted plates between the chambers on the passive bending of the actuator was examined. The obtained results were evaluated and compared to determine how external chamber plates of given thicknesses affect the operational performance of a soft actuator. Full article

(This article belongs to the Special Issue Recent Advances in Pneumatic Soft Actuators)

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Open AccessArticle

Design Optimization of a Miniaturized Pneumatic Artificial Muscle and Experimental Validation

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Shakila Zabihollah

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Seyed Alireza Moezi

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Ramin Sedaghati

Actuators 2023, 12(6), 221; https://doi.org/10.3390/act12060221 - 25 May 2023

Abstract

Miniaturized pneumatic artificial muscles (MPAMs) are widely utilized in various applications due to their unique characteristics, such as a high power-to-weight ratio, flexibility, and compatibility with the human environment, as well as being compact enough to fit within small-scale mechanical systems. Maximizing the [...] Read more.

Miniaturized pneumatic artificial muscles (MPAMs) are widely utilized in various applications due to their unique characteristics, such as a high power-to-weight ratio, flexibility, and compatibility with the human environment, as well as being compact enough to fit within small-scale mechanical systems. Maximizing the amount of force generated by these actuators while keeping their dimensions minimized can greatly affect their efficiency. In this study, a formal design optimization problem was formulated to identify optimal sizes of MPAMs while maximizing their blocked force as a novel approach to address the issue of low force outputs of these actuators. A force model for an MPAM including various correction terms was derived to better predict the response behavior of the actuator. The optimization results reveal that an MPAM with a bladder that has an outer diameter of 6 mm and a thickness of 0.7 mm, as well as a braid angle of 72 degrees, can produce up to almost 239 N of blocked force if the inlet pressure is increased to 600 kPa. An MPAM with optimal parameters was subsequently fabricated and experimentally tested to evaluate its quasi-static response behavior and to validate the theoretical optimization results. Experimental tests were conducted under a wide range of pressures (0–300 kPa) to evaluate the variation of the generated blocked force versus inlet pressure. The overall error between the simulation and the experimental blocked forces was found to be less than 10%. This study represents a significant contribution to the design optimization of MPAMs, and the resulting optimal design offers potential applications in various fields, from soft robots to medical devices. Full article

(This article belongs to the Section Miniaturized and Micro Actuators)

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Open AccessArticle

A Hybridization Grey Wolf Optimizer to Identify Parameters of Helical Hydraulic Rotary Actuator

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Actuators 2023, 12(6), 220; https://doi.org/10.3390/act12060220 - 25 May 2023

Abstract

Based on the grey wolf optimizer (GWO) and differential evolution (DE), a hybridization algorithm (H-GWO) is proposed to avoid the local optimum, improve the diversity of the population, and compromise the exploration and exploitation appropriately. The mutation and crossover principles of the DE [...] Read more.

Based on the grey wolf optimizer (GWO) and differential evolution (DE), a hybridization algorithm (H-GWO) is proposed to avoid the local optimum, improve the diversity of the population, and compromise the exploration and exploitation appropriately. The mutation and crossover principles of the DE algorithm are introduced into the GWO algorithm, and the opposition-based optimization learning technology is combined to update the GWO population to increase the population diversity. The algorithm is then benchmarked against nine typical test functions and compared with other state-of-the-art meta-heuristic algorithms such as particle swarm optimization (PSO), GWO, and DE. The results show that the proposed H-GWO algorithm can provide very competitive results. On this basis, the forgetting factor recursive least squares (FFRLS) method and the proposed H-GWO algorithm are combined to establish a parameter identification algorithm to identify parameters of the helical hydraulic rotary actuator (HHRA) with nonlinearity and uncertainty questions. In addition, the proposed method is verified by practical identification experiments. After comparison with the least squares (LS), recursive least squares (RLS), FFRLS, PSO, and GWO results, it can be concluded that the proposed method (H-GWO) has higher identification accuracy. Full article

(This article belongs to the Section Aircraft Actuators)

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Open AccessArticle

Towards Metaverse: Utilizing Extended Reality and Digital Twins to Control Robotic Systems

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Víctor Blanco Bataller

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Niko Laivuori

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Mika Luimula

Actuators 2023, 12(6), 219; https://doi.org/10.3390/act12060219 - 24 May 2023

Abstract

Digitalization shapes the ways of learning, working, and entertainment. The Internet, which enables us to connect and socialize is evolving to become the metaverse, a post-reality universe, enabling virtual life parallel to reality. In addition to gaming and entertainment, industry and academia have [...] Read more.

Digitalization shapes the ways of learning, working, and entertainment. The Internet, which enables us to connect and socialize is evolving to become the metaverse, a post-reality universe, enabling virtual life parallel to reality. In addition to gaming and entertainment, industry and academia have noticed the metaverse’s benefits and possibilities. For industry, the metaverse is the enabler of the future digital workplace, and for academia, digital learning spaces enable realistic virtual training environments. A connection bridging the virtual world with physical production systems is required to enable digital workplaces and digital learning spaces. In this publication, extended reality–digital twin to real use cases are presented. The presented use cases utilize extended reality as high-level user interfaces and digital twins to create a bridge between virtual environments and robotic systems in industry, academia, and underwater exploration. Full article

(This article belongs to the Special Issue Modeling, Optimization and Control of Robotic Systems)

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Open AccessArticle

Experimental Observations of Transient Flows in Separation Control Using a Plasma Actuator

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Actuators 2023, 12(6), 218; https://doi.org/10.3390/act12060218 - 23 May 2023

Abstract

This paper presents the experimental results of separation and reattachment transient flow processes over a NACA0015 airfoil wing when using a plasma actuator for flow control. In addition, it addresses the flow behavior in the transient processes when the flow control device is [...] Read more.

This paper presents the experimental results of separation and reattachment transient flow processes over a NACA0015 airfoil wing when using a plasma actuator for flow control. In addition, it addresses the flow behavior in the transient processes when the flow control device is activated or deactivated, providing insights for future feedback-based active flow control. This approach offers the benefit of enhanced aerodynamic capabilities. The experiments were conducted at a Reynolds number of 66,000 and an angle of attack of 13 degrees for leading-edge separation without control. The plasma actuator was installed on the leading edge of the wing, with a voltage of 8 kV, base frequency of 30 kHz, and burst frequencies ranging from 100 Hz to 600 Hz. Particle image velocimetry was employed for the flow field velocity measurements, and surface pressure data were obtained using eight piezoelectric pressure sensors. The first proper orthogonal decomposition mode of the transient flow velocity field is the focus of this paper and the flow behavior is quantitatively discussed. The results reveal details about the flow separation and reattachment transient processes such as their flow structures and their evolution over time. It is concluded that the time asymmetry between the separation and reattachment transient processes could be leveraged for further improvements to the efficiency of actuators. Full article

(This article belongs to the Special Issue Dielectric Barrier Discharge Plasma Actuator for Active Flow Control)

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Open AccessArticle

Neural Network Sliding Model Control of Radial Translation for Magnetically Suspended Rotor (MSR) in Control Moment Gyro

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Actuators 2023, 12(6), 217; https://doi.org/10.3390/act12060217 (registering DOI) - 23 May 2023

Abstract

For a magnetically suspended control moment gyro (MSCMG), the high-speed rotor is actively suspended by magnetic bearings of 5-DOF, but the nonlinearity of the magnetic suspension force is one of the main reasons for the poor accuracy of radial translation control of the [...] Read more.

For a magnetically suspended control moment gyro (MSCMG), the high-speed rotor is actively suspended by magnetic bearings of 5-DOF, but the nonlinearity of the magnetic suspension force is one of the main reasons for the poor accuracy of radial translation control of the magnetically suspended rotor (MSR). To solve this problem, here, the characteristics of the magnetic suspension force are analyzed, and the nonlinear dynamic model of MSR is established. A sliding mode control (SMC) based on a neural network is presented, and the radial basis function (RBF) neural network is adopted to approximate the nonlinear displacement stiffness and the current displacement stiffness to weaken the chattering in SMC to improve the control accuracy of the MSR. The stability of the neural network SMC for the MSR is analyzed based on Lyapunov functions, and the rules of updating network weights are presented based on adaptive algorithms. Compared with these existing classic control methods, the simulation and experimental tests performed on a single-gimbal MSCMG with an angular momentum of 200 N.m.s indicated that this neural network SMC for MSR’s radial translation can not only make its suspension more stable but can also make its position precision higher. Full article

(This article belongs to the Special Issue Advanced Technologies on the Control Method of Electromagnetic Actuator)

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Open AccessArticle

Integrated Security Control for Nonlinear CPS with Actuator Fault and FDI Attack: An Active Attack-Tolerant Approach

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Actuators 2023, 12(5), 216; https://doi.org/10.3390/act12050216 - 22 May 2023

Abstract

This paper investigated the co-design problem of less conservative integrated security control and communication for a nonlinear cyber-physical system (CPS) with an actuator fault and false data injection (FDI) attacks. Firstly, considering the efficient utilisation and allocation of computing and communication resources, an [...] Read more.

This paper investigated the co-design problem of less conservative integrated security control and communication for a nonlinear cyber-physical system (CPS) with an actuator fault and false data injection (FDI) attacks. Firstly, considering the efficient utilisation and allocation of computing and communication resources, an integrated framework was proposed from the perspective of active defence against FDI attacks. Secondly, the actuator fault and FDI attacks were augmented as a vector, and a robust observer was proposed to estimate the system state, actuator fault and FDI attacks. Furthermore, based on the obtained estimation results and the location of the FDI attack in the dual-end network, we designed an integrated security control strategy of active attack tolerance and active fault tolerance and, by constructing Lyapunov–Krasovskii functions and using time-delay system theory and the affine Bessel–Legendre inequality, a less conservative co-design method for integrated security control and network communication resource saving was developed. Finally, a simulation experiment of a quadruple tank was carried out to demonstrate the effectiveness of the proposed method. Full article

(This article belongs to the Section Control Systems)

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Open AccessArticle

Ferroelectret Polypropylene Foam-Based Piezoelectric Energy Harvester for Different Seismic Mass Conditions

by

Chandana Ravikumar

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Vytautas Markevicius

Actuators 2023, 12(5), 215; https://doi.org/10.3390/act12050215 - 22 May 2023

Abstract

Energy harvesting technologies and material science has made it possible to tap into the abundant amount of surrounding vibrational energy to efficiently convert it into useable energy providing power to portable electronics and IoT devices. Recent investigations show that the piezoelectric effect is [...] Read more.

Energy harvesting technologies and material science has made it possible to tap into the abundant amount of surrounding vibrational energy to efficiently convert it into useable energy providing power to portable electronics and IoT devices. Recent investigations show that the piezoelectric effect is created in cellular polymers called ferroelectrets. These cellular-compliant polymers with polarized pores have a piezoelectric response to generate electrical energy when subjected to mechanical strain or surrounding vibration. It is found that there is a significant difference between ferroelectret polarized cellular polypropylene foam and traditional piezoelectric polymers such as polyvinylidene fluoride (PVDF). The former has approximately ten times higher piezoelectric coefficient than the latter. This means that with an acceleration of 9.81

m / s^{2}

force on this material, ferroelectrets generate up to 39 (µW/g/

{m m}^{3}

) power output. Designing a polypropylene-based piezoelectric energy harvester based on the d33 mode of vibration can be challenging due to several factors, as it requires balancing multiple factors such as mechanical stability, piezoelectric response, circuit topology, electrode size, spacing, placement relative to the piezoelectric material, and so on. This paper proposes the preliminary experimental investigation of ferroelectret cellular polypropylene foam in harvesting performance. Suggestions of different approaches for the structural design of energy harvesters are provided. The vibration-dependent response and generated output are examined concerning pulse or sinusoidal input excitation. The voltage generated for both excitations is compared and suggestions are provided regarding the suitable kind of excitation for the chosen ferroelectret material. Finally, conclusions and prospects for ferroelectret materials used in energy-harvesting applications are given. Full article

(This article belongs to the Special Issue Smart Systems for Vibration Damping, Control and Energy Harvesting Based on Piezoelectric Actuators: Latest Findings and Applications)

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Open AccessArticle

Design of Two-Degree-of-Freedom Fractional-Order Internal Model Control Algorithm for Pneumatic Control Valves

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Actuators 2023, 12(5), 214; https://doi.org/10.3390/act12050214 - 22 May 2023

Abstract

In response to the problems of the inaccurate pneumatic control valve model, the slow valve position control, and the low precision in the industrial control process, some improvement methods are proposed. Firstly, the fractional-order concept is introduced based on the first-order inertia model [...] Read more.

In response to the problems of the inaccurate pneumatic control valve model, the slow valve position control, and the low precision in the industrial control process, some improvement methods are proposed. Firstly, the fractional-order concept is introduced based on the first-order inertia model and IBBO (improved biogeography-based optimization) is used for iteration to obtain a specific transfer function model. Secondly, a fractional-order and two-degree-of-freedom combined internal model control algorithm is proposed. Finally, semi-physical experiments are carried out on a semi-physical experimental platform. The results show that in the field of pneumatic regulating valves, the fractional-order model has good adaptability and effectiveness, and the two-degree-of-freedom fractional-order internal model control algorithm also effectively improves the accuracy, speed, and robustness of the valve position control. Full article

(This article belongs to the Special Issue Applications of Finite-Time Disturbance Rejection Control Method)

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Open AccessReview

Loss Determination Techniques for Piezoelectrics: A Review

by

Yoonsang Park

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Minkyu Choi

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Kenji Uchino

Actuators 2023, 12(5), 213; https://doi.org/10.3390/act12050213 - 21 May 2023

Abstract

Nowadays, heat dissipation in electronic devices is one of the serious issues to be resolved in energy and environmental terms. Piezoelectric materials are being utilized in many electronic devices, yet the roadblock toward further miniaturization of piezoelectric devices was identified as heat dissipation. [...] Read more.

Nowadays, heat dissipation in electronic devices is one of the serious issues to be resolved in energy and environmental terms. Piezoelectric materials are being utilized in many electronic devices, yet the roadblock toward further miniaturization of piezoelectric devices was identified as heat dissipation. Three types of losses (dielectric, elastic, and piezoelectric) are known to be related to the heat dissipation mechanism of piezoelectric materials, therefore obtaining accurate values of the loss factors is essential for minimizing the heat dissipation of piezoelectric devices. The purpose of this review is to introduce several loss determination techniques for piezoelectric materials. The review starts with brief discussions of the loss factors and of the importance of piezoelectric loss that is related to the antiresonance frequency. Then, the review covers the methods developed by our research group, including High Power Piezoelectric Characterization Systems (HiPoCS^TM), the crystallographic orientation method and the partial electrode method, as well as other methods such as the pulse-echo method and computer-based approaches. The review continues with a discussion of piezoelectric device modeling (analytical solution and equivalent circuits) that considers loss factors. Finally, the review provides concluding remarks for addressing current issues and suggesting possible solutions. Full article

(This article belongs to the Special Issue Piezoelectric Actuators—A Special Issue in Honor of Prof. Dr. Kenji Uchino)

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Open AccessArticle

Numerical Study on the Heating Effect of a Spring-Loaded Actuator—Part II: Optimization Design of Heater Parameters

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Actuators 2023, 12(5), 212; https://doi.org/10.3390/act12050212 - 21 May 2023

Abstract

Unfavorable temperatures and humidity will cause the failure of spring actuators. In order to ensure the safe operation of the actuator, it is necessary to optimize the design of the built-in heater system of the actuator itself. In this study, an experimental design [...] Read more.

Unfavorable temperatures and humidity will cause the failure of spring actuators. In order to ensure the safe operation of the actuator, it is necessary to optimize the design of the built-in heater system of the actuator itself. In this study, an experimental design and a response surface model were used to fit the empirical formulas for the minimum temperature, maximum humidity, and maximum temperature on the heater surface. On this basis, a genetic algorithm was used to establish the optimal size of the heater in the chamber of the spring actuator. The study results show that the air inside the actuator shows a trend of a decrease in temperature and an increase in relative humidity from top to bottom. The empirical equation obtained by fitting the second-order response surface model has high accuracy, and the maximum prediction errors for the minimum temperature, maximum relative humidity, and maximum temperature of the heater surface of the spring actuator are −0.5%, 11.7%, and 4.7%, respectively. When the environmental temperature reduces from 313 K to 233 K, the optimal heating power of the heater increases from 10 W to 490 W, the optimal relative length increases from 3.57 to 6, and the optimal relative width increases from 1 to 5.3. Therefore, the study can act as a reference for the temperature and humidity control system of future actuators. Full article

(This article belongs to the Special Issue Actuators in 2022)

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Open AccessArticle

Investigations of the Crystallographic Orientation on the Martensite Variant Reorientation of the Single-Crystal Ni-Mn-Ga Cube and Its Composites for Actuator Applications

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Actuators 2023, 12(5), 211; https://doi.org/10.3390/act12050211 - 20 May 2023

Abstract

High-speed actuators are greatly required in this decade due to the fast development of future technologies, such as Internet-of-Things (IoT) and robots. The ferromagnetic shape memory alloys (FSMAs), whose shape change could be driven by applying an external magnetic field, possess a rapid [...] Read more.

High-speed actuators are greatly required in this decade due to the fast development of future technologies, such as Internet-of-Things (IoT) and robots. The ferromagnetic shape memory alloys (FSMAs), whose shape change could be driven by applying an external magnetic field, possess a rapid response. Hence, these materials are considered promising candidates for the applications of future technologies. Among the FSMAs, the Ni-Mn-Ga-based materials were chosen for their large shape deformation strain and appropriate phase transformation temperatures for near-room temperature applications. Nevertheless, it is widely known that both the intrinsic brittleness of the Ni-Mn-Ga alloy and the constraint of shape deformation strain due to the existence of grain boundaries in the polycrystal inhibit the applications. Therefore, various Ni-Mn-Ga-based composite materials were designed in this study, and their shape deformation behaviors induced by compressive or magnetic fields were examined by the in situ micro CT observations. In addition, the dependence of the martensite variant reorientation (MVR) on the crystallographic directions was also investigated. It was found that most of the MVRs are active within the magnetic field range applied in the regime of the <100>_p, <110>_p, and <111>_p of the single-crystal {100}_p Ni-Mn-Ga cubes. Full article

(This article belongs to the Special Issue Recent Advances in Shape-Memory Materials and Actuators)

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Open AccessArticle

Microactuation of Magnetic Nanofluid Enabled by a Pulsatory Rotating Magnetic Field

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Lucian Pîslaru-Dănescu

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George-Claudiu Zărnescu

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Eros-Alexandru Pătroi

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Rareș-Andrei Chihaia

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Gabriela Telipan

Actuators 2023, 12(5), 210; https://doi.org/10.3390/act12050210 - 19 May 2023

Abstract

A microactuation process was developed with the help of four coils that generate a pulsatory rotating magnetic field. A small actuator stator, which contains a 46 mm acrylonitrile butadiene styrene (ABS) opened box and four coils with E-type ferrite cores, was constructed. Simulations [...] Read more.

A microactuation process was developed with the help of four coils that generate a pulsatory rotating magnetic field. A small actuator stator, which contains a 46 mm acrylonitrile butadiene styrene (ABS) opened box and four coils with E-type ferrite cores, was constructed. Simulations were made for different Duty Cycles, 0.2, 0.5, 0.72 and 0.9, and distances above the E cores, between 0.01 and 6 mm. These simulations determined the magnetic bubble inflating distance, the saturation regions and the average forces that are responsible for nanofluid flow inside the ABS box. An electrical driving scheme was designed, and a drive was constructed to activate four inductive loads that generate a pulsatory rotating magnetic field. The electronic drive can change the actuation frequency (rotation speed) between 1 Hz and 25 Hz and can adjust the Duty Cycle between 5% and 95% (driving force). From simulations and experiments, it was observed that the Duty Cycle must be limited to 0.7 to avoid the magnetic nanofluid saturation at 45 mT. It was found that three applications use a pulsatory rotating magnetic field: a small motor, a small flat pump and a manipulating sheet matrix for displays or chemical droplets mixing. Full article

(This article belongs to the Special Issue Recent Advances in the Design and Applications for Magnetoelastic and Electroelastic Actuators)

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Open AccessArticle

Sliding Mode Active Disturbance Rejection Control of Permanent Magnet Synchronous Motor Based on Improved Genetic Algorithm

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Actuators 2023, 12(5), 209; https://doi.org/10.3390/act12050209 - 19 May 2023

Abstract

Sliding mode control has been widely used to control permanent magnet synchronous motors (PMSM). However, the parameters of the sliding mode controller are difficult to be tuned, which makes the control performance of PMSM hard to be improved. A nonlinear sliding mode control [...] Read more.

Sliding mode control has been widely used to control permanent magnet synchronous motors (PMSM). However, the parameters of the sliding mode controller are difficult to be tuned, which makes the control performance of PMSM hard to be improved. A nonlinear sliding mode control method that integrated a nonlinear reaching law (NRLSMC) and extended state observer (ESO) is proposed in this paper, whose parameters are tuned by an improved genetic algorithm (IGA). The control performance of the nonlinear reaching law in the nonlinear sliding mode controller is analyzed, whose stability is verified based on the Lyapunov theorem. An extended state observer is integrated into the above controller to further improve the anti-interference capability, and compensate for the observed external disturbance of the system into the speed controller in sliding mode. The optimal parameters of the above sliding mode control are tuned by IGA combined with the system speed loop model. The performance of the proposed controller is numerically simulated in MATLAB/Simulink and verified in a control system rapid control prototype (RCP) experimental platform built based on dSPACE 1202. Numerical simulation and experimental results show that the proposed controller can make the PMSM control system with the advantages of no overshoot, fast response, and strong robustness. Full article

(This article belongs to the Special Issue Applications of Intelligent Control in Actuators Systems)

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Open AccessArticle

Actuation Behavior of Hydraulically Amplified Self-Healing Electrostatic (HASEL) Actuator via Dimensional Analysis

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Alexandrea Washington

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Ji Su

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Kwang J. Kim

Actuators 2023, 12(5), 208; https://doi.org/10.3390/act12050208 - 18 May 2023

Abstract

Electroactive polymer (EAP) actuators are an example of a novel soft material device that can be used for several applications including artificial muscles and lenses. The field of EAPs can be broken down into a few fields; however, the field that will be [...] Read more.

Electroactive polymer (EAP) actuators are an example of a novel soft material device that can be used for several applications including artificial muscles and lenses. The field of EAPs can be broken down into a few fields; however, the field that will be discussed in this study is that of Soft Electrohydraulic (SEH or EH) actuators. The device that will specifically be studied is the Hydraulically Amplified Self-Healing Electrostatic (HASEL) actuator. The design of the HASEL actuator is simple. There are two compliant films that house a dielectric liquid, and with the application of a voltage potential, there is an output displacement and force. However, the actuation mechanism is more complex, thus there is a need to understand theoretically and experimentally how the actuator works. This study analytically describes the electrode closure and the experimental testing of the actuators. Then, dimensional analysis techniques are used to determine what factors are contributing to the function of the actuator. For this study, eight dimensionless Π groups were found based on the derived analytical equation. These Π groups were determined based on the input voltage, density, viscosity, and elastic modulus of the materials; these were chosen because of their major contribution to the experimental data. The Π groups that are of particular importance are related to the characteristic length, which is directly related to the displacement of the fluid, the fluid velocity, the fluid pressure, and the dielectric constant. From this study, relationships between the output force, the electrostatic contributions, and other parameters were determined. All in all, this type of analysis can provide guidance on the development of high-performance HASEL actuators. Full article

(This article belongs to the Special Issue Actuators in 2022)

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Open AccessArticle

Distributed Cooperative Cruise Control for High-Speed Trains with Energy-Saving Optimization

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Actuators 2023, 12(5), 207; https://doi.org/10.3390/act12050207 - 17 May 2023

Abstract

With the aim of improving the energy utilization during the cooperative operation of multiple trains, this paper proposes an optimal distributed cooperative cruise control strategy to ensure safe and efficient tracking. A performance index function with distributed characteristics is constructed by considering the [...] Read more.

With the aim of improving the energy utilization during the cooperative operation of multiple trains, this paper proposes an optimal distributed cooperative cruise control strategy to ensure safe and efficient tracking. A performance index function with distributed characteristics is constructed by considering the state errors among trains and energy consumption. An LQR-based optimal design technique is applied to cooperative cruise control to optimize the cooperative control gain to find the optimal solution. Additionally, the scalar coupling gains are introduced to decouple the design of the optimal cooperative control gain from the communication topology of trains. Thus, the proposed strategy is robust for arbitrary directed communication topologies and can eventually be used to achieve the distributed tracking optimization of multiple trains. The asymptotic stability of the system is proved strictly by exploiting the Hurwitz and Lyapunov stability theorem. A numerical simulation example is given to verify the feasibility and effectiveness of the proposed strategy. Full article

(This article belongs to the Section Control Systems)

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Open AccessArticle

Multi-Objective Optimal Design of μ–Controller for Active Magnetic Bearing in High-Speed Motor

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Yuanwen Li

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Changsheng Zhu

Actuators 2023, 12(5), 206; https://doi.org/10.3390/act12050206 - 17 May 2023

Abstract

In this paper, a control strategy based on the inverse system decoupling method and μ-synthesis is proposed to control vibration in a rigid rotor system with active magnetic bearings that are built into high-speed motors. First, the decoupling method is used to [...] Read more.

In this paper, a control strategy based on the inverse system decoupling method and μ-synthesis is proposed to control vibration in a rigid rotor system with active magnetic bearings that are built into high-speed motors. First, the decoupling method is used to decouple the four-degrees-of-freedom state equation of the electromagnetic bearing rigid rotor system; the strongly coupled and nonlinear rotor system is thus decoupled into four independent subsystems, and the eigenvalues of the subsystems are then configured. The uncertain parametric perturbation method is used to model the subsystem, and the multi-objective ant colony algorithm is then used to optimize the sensitivity function and the pole positions to obtain the optimal μ-controller. The closed-loop system thus has the fastest possible response, the strongest internal stability, and the best disturbance rejection capability. Then, the unbalanced force compensation algorithm is used to compensate for the high-frequency eccentric vibration; this algorithm can attenuate the unbalanced eccentric vibration of the rotor to the greatest extent and improve the robust stability of the rotor system. Finally, simulations and experiments show that the proposed control strategy can allow the rotor to be suspended stably and suppress its low-frequency and high-frequency vibrations effectively, providing excellent internal and external stability. Full article

(This article belongs to the Special Issue Linear Motors and Direct-Drive Technology)

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Open AccessArticle

Evaluation of Spiral Pneumatic Rubber Actuator Using Finite Element Analysis for Radial Transportation

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Yujin Jang

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Hiroyuki Nabae

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Koichi Suzumori

Actuators 2023, 12(5), 205; https://doi.org/10.3390/act12050205 - 17 May 2023

Abstract

Emerging actuators with various soft materials and a traveling wave motion are frequently discussed. Various configurations have been proposed and their resulting performances investigated, but it remains challenging to realize large strokes. This study presents an experimentally validated nonlinear finite element model to [...] Read more.

Emerging actuators with various soft materials and a traveling wave motion are frequently discussed. Various configurations have been proposed and their resulting performances investigated, but it remains challenging to realize large strokes. This study presents an experimentally validated nonlinear finite element model to predict the deformation produced by a spiral pneumatic rubber actuator to generate a traveling wave motion. The actuator consists of a membrane mounted on a rubber substrate with three air chambers in a spiral configuration. The sequential deformations of the successive chambers interact with each other and produce radial traveling waves on the membrane surface, driving the objects placed on the actuator. Finite element analysis with ANSYS computer software was used to analyze the elastic movement by considering the influence of different initial structural types. The simulation results indicated an optimal structure with specific ratios. A reasonable correlation was obtained during experimental validation; the predicted displacement values were approximately 17% smaller than the experimental values. Finally, the transportation performance of the prototype was tested, and a velocity of 2.28 mm/s in the desired direction was achieved. We expect that our demonstration will expand the range of applications of the spiral pneumatic rubber actuator to include conveying or worm-like robots. Full article

(This article belongs to the Special Issue Recent Advances in Pneumatic Soft Actuators)

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Open AccessArticle

Analysis of the Antagonistic Arrangement of Pneumatic Muscles Inspired by a Biological Model of the Human Arm

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Actuators 2023, 12(5), 204; https://doi.org/10.3390/act12050204 - 17 May 2023

Abstract

Technical solutions based on biological models are the subject of research by a wide range of experts and mainly concern their mechanical use. When designing a suitable actuator, they use the physical methods of biological representatives, of which a large group consists of [...] Read more.

Technical solutions based on biological models are the subject of research by a wide range of experts and mainly concern their mechanical use. When designing a suitable actuator, they use the physical methods of biological representatives, of which a large group consists of actuators generally referred to as artificial muscles, while another group uses compressed air as an energy carrier. In order to perform the measurements described in this article, a test mechanism based on the opposing arrangement of a pair of pneumatic muscles was constructed. Measurements on the test mechanism were made at set constant pressures in the range of 0.4 MPa to 0.6 MPa, while at each pressure, measurements were made for the counterload range from 0 N to 107.87 N. The measured values were recorded using a microcontroller and subsequently processed into graphic outputs. As part of the measurements, a comparative measurement of the same opposite arrangement of a pair of linear double-acting pneumatic actuators with a single-sided piston rod was also performed. The experiment and measurements were carried out in order to determine the suitability of using pneumatic artificial muscles in the selected arrangement for the implementation of a mechanism imitating the human arm. The target parameters of the experiment were the reaction speed of the course of force when filling the muscle under load and the reaction of the mechanism to a change in the set pressure in the pneumatic system. The summary of the comparison of the measured results is the content of the discussion in this article. Full article

(This article belongs to the Special Issue Artificial Muscles for Biorobotics: Study, Application and Future Perspectives)

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