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Actuators, Volume 12, Issue 7 (July 2023) – 44 articles

Cover Story (view full-size image): This study focused on electromagnetic actuation for controlling magnetic microrobots in minimally invasive therapies. It introduced a human-in-the-loop approach with haptic assistance for safe piloting and utilizing doctors' expertise. This enhances safety and public acceptability, especially in drug delivery inside the body. A haptic device enabled the targeted delivery of microrobots within blood vessels. The novel magnetic guidance strategy optimized the process using two magnetic forces. The electromagnetic actuation system offered up to 70 mm of workspace, allowing easy access from all sides. This design enables efficient microparticle manipulation in a larger 3D workspace, surpassing existing limitations. Two-dimensional and three-dimensional in vitro analysis validated the magnetic navigation platform's efficacy. View this paper
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15 pages, 8255 KiB  
Article
Augmented Reality Based Distant Maintenance Approach
Actuators 2023, 12(7), 302; https://doi.org/10.3390/act12070302 - 24 Jul 2023
Viewed by 1481
Abstract
This paper focuses on the implementation of Industry 4.0-based maintenance approaches using AR technology. The primary objective is to highlight the benefits of AR in maintenance and provide a framework for implementing AR-based maintenance systems. AR can assist maintenance personnel in performing maintenance [...] Read more.
This paper focuses on the implementation of Industry 4.0-based maintenance approaches using AR technology. The primary objective is to highlight the benefits of AR in maintenance and provide a framework for implementing AR-based maintenance systems. AR can assist maintenance personnel in performing maintenance tasks more efficiently by providing real-time instructions and information. By overlaying virtual information on real equipment, AR can guide maintenance personnel through maintenance procedures, reducing human errors and improving the quality of the work. AR can also provide remote assistance to maintenance personnel, allowing experts to remotely guide less experienced personnel through complex maintenance procedures. The proposed application provides motorcycle service assistance using AR and telepresence technologies. It enables remote monitoring of the service flow and performs an automated identification of parts. The system provides instructions for disassembling more complex mechanical components, provides a 3D model of the object, and enables ordering of the necessary parts. Full article
(This article belongs to the Section Actuators for Manufacturing Systems)
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21 pages, 4064 KiB  
Article
Research on CNN-LSTM Brake Pad Wear Condition Monitoring Based on GTO Multi-Objective Optimization
Actuators 2023, 12(7), 301; https://doi.org/10.3390/act12070301 - 24 Jul 2023
Viewed by 1114
Abstract
As the core component of the automobile braking system, brake pads have a complex structure and high failure rate. Their accurate and effective state monitoring can help to evaluate the safety performance of brake pads and avoid accidents caused by brake failure. The [...] Read more.
As the core component of the automobile braking system, brake pads have a complex structure and high failure rate. Their accurate and effective state monitoring can help to evaluate the safety performance of brake pads and avoid accidents caused by brake failure. The wear process of automobile brake pads is a gradual, nonlinear, and non-stationary time-varying system, and it is difficult to extract its features. Therefore, this paper proposes a CNN-LSTM brake pad wear state monitoring method. This method uses a Convolutional Neural Network (CNN) to complete the deep mining of brake pad wear characteristics and realize data dimensionality reduction, and a Long Short-Term Memory (LSTM) network to capture the time dependence of the brake pad wear sequence, so as to construct the nonlinear mapping relationship between brake pad wear characteristics and brake pad wear values. At the same time, the artificial Gorilla Troops Optimization (GTO) algorithm is used to perform multi-objective optimization of the network structure parameters in the CNN-LSTM model, and its powerful global search ability improves the monitoring effect of the brake pad wear status. The results show that the CNN-LSTM model based on GTO multi-objective optimization can effectively monitor the wear state of brake pads, and its coefficient of determination R2 value is 0.9944, the root mean square error RMSE value is 0.0023, and the mean absolute error MAE value is 0.0017. Compared with the BP model, CNN model, LSTM model, and CNN-LSTM model, the value of the coefficient of determination R2 is the closest to 1, which is increased by 8.29%, 5.52%, 4.47%, 3.30%, respectively, which can more effectively realize the monitoring and intelligent early warning of the brake pad wear state. Full article
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21 pages, 8048 KiB  
Article
An Optimized Design of the Soft Bellow Actuator Based on the Box–Behnken Response Surface Design
Actuators 2023, 12(7), 300; https://doi.org/10.3390/act12070300 - 24 Jul 2023
Cited by 2 | Viewed by 1306
Abstract
Soft actuator technology is extensively utilized in robotic manipulation applications. However, several existing designs of soft actuators suffer from drawbacks such as a complex casting process, a multi-air chamber configuration, and insufficient grasping force. In this study, we propose a novel soft bellow [...] Read more.
Soft actuator technology is extensively utilized in robotic manipulation applications. However, several existing designs of soft actuators suffer from drawbacks such as a complex casting process, a multi-air chamber configuration, and insufficient grasping force. In this study, we propose a novel soft bellow design featuring a single air chamber, which simplifies the fabrication process of the actual model. To enhance the performance of the proposed design, we employ the Box–Behnken response surface design to generate a design matrix for implementing different levels of design factors in the finite element model. The FEA response is then subjected to an analysis of variance to identify significant factors and establish a regression model for deformation and stress response prediction. Among the considered responses, the wall thickness emerges as the most influential factor, followed by the divided ratio of radians and the number of bellows. Validation of the optimized soft bellow actuator’s deformation response is performed through comparison with experimental data. Moreover, the soft bellow actuator is capable of exerting a pulling force of 8.16 N when used in conjunction with a simple gripper structure design, enabling effective object manipulation. Additionally, the soft bellow design boasts cost-effectiveness and easy moldability, facilitating seamless integration with different gripper frames for diverse applications. Its simplicity and versatility make it a promising choice for various robotic manipulation tasks. Full article
(This article belongs to the Special Issue Soft Actuators and Robotics)
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24 pages, 24525 KiB  
Article
Monolithic PneuNets Soft Actuators for Robotic Rehabilitation: Methodologies for Design, Production and Characterization
Actuators 2023, 12(7), 299; https://doi.org/10.3390/act12070299 - 24 Jul 2023
Cited by 2 | Viewed by 1145
Abstract
Soft-robotics for biomedical applications, such as rehabilitation robots, is a field of intense research activity. Different actuation solutions have been proposed in the last decades, involving study and development of soft actuators of different types and materials. The purpose of the paper is [...] Read more.
Soft-robotics for biomedical applications, such as rehabilitation robots, is a field of intense research activity. Different actuation solutions have been proposed in the last decades, involving study and development of soft actuators of different types and materials. The purpose of the paper is to present procedures for an optimized design, and for easy and low cost production and characterization of monolithic PneuNets soft-actuators. An innovative design approach has been developed. The parameterization of the geometry, combined with FEM simulations is the basis for an optimized design of the actuator, as a function of the obtained bending and of the generated forces. Simple and cheap characterization setup and procedures have been identified for the actuator characterization and for simulation results validation. An easy and low-cost fabrication method based on lost wax core obtained through a silicone based mold has been developed for a monolithic PneuNets soft-actuator. The proposed solution performs well in bending, without the need for a strain limiting layer. Experimental results validated simulations, confirming the feasibility of adopting an optimized simulation-based design approach. Full article
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18 pages, 5705 KiB  
Article
Dynamic Analysis and Piezoelectric Energy Harvesting from a Nonideal Portal Frame System including Nonlinear Energy Sink Effect
Actuators 2023, 12(7), 298; https://doi.org/10.3390/act12070298 - 22 Jul 2023
Viewed by 1142
Abstract
This paper investigates, through numerical simulations, the application of piezoelectric materials in energy generation. The mathematical model describes a U-shaped portal frame system, excited by an engine with unbalanced mass and coupled to a nonlinear energy sink (NES), which is used as a [...] Read more.
This paper investigates, through numerical simulations, the application of piezoelectric materials in energy generation. The mathematical model describes a U-shaped portal frame system, excited by an engine with unbalanced mass and coupled to a nonlinear energy sink (NES), which is used as a passive vibration absorber. The influence of the piezoelectric material parameters used in the energy collection and the dimensioning parameters of the NES system is deeply analyzed in this paper. Numerical simulations are presented considering all combinations of the parameters of the piezoelectric material model and the NES. The system dynamics were analyzed through phase diagrams and the 0–1 test. The estimation of energy collection was carried out by calculating the average power. The numerical results show that a more significant potential for energy generation is obtained for certain combinations of parameters, as well as chaotic behavior in some cases. Full article
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17 pages, 2448 KiB  
Article
Improved Vehicle Vibration Control through Optimization of Suspension Parameters Using the Response Surface Method and a Non-Linear Programming with a Quadratic Lagrangian Algorithm
Actuators 2023, 12(7), 297; https://doi.org/10.3390/act12070297 - 21 Jul 2023
Cited by 1 | Viewed by 1314
Abstract
Vibration-control techniques generally fall into two categories: passive methods that optimize the structure of the suspension to absorb any impact from the ground, and active methods that directly control the vertical force of the suspension by hydraulic or electric actuators when the vehicle [...] Read more.
Vibration-control techniques generally fall into two categories: passive methods that optimize the structure of the suspension to absorb any impact from the ground, and active methods that directly control the vertical force of the suspension by hydraulic or electric actuators when the vehicle traverses a bumpy road. In this study, a vibration-control method is described that employs both an optimal controller and suspension parameter optimization. Continuous speed bumps are implemented to simulate more complex and realistic driving conditions. First, a vehicle system is modeled using a semi-recursive multibody formulation, which allows for a more precise description of the longitudinal–vertical dynamics. Then, an optimal control method for vehicle vibration control is introduced. Second, the Latin hypercube design is utilized to analyze the response surface methodology (RSM) model. For suspension optimization, the RSM model and the non-linear programming with a quadratic Lagrangian (NLPQL) algorithm are employed. Thirdly, both passive suspension optimization and active motion control are employed for vibration control. The results indicate that the presented method can effectively control vehicle vibration, decreasing the average vibration by 30.8%. The results suggest that the novel approach can also enhance the ride comfort in autonomous vehicles traversing, e.g., a series of speed bumps. Full article
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18 pages, 7747 KiB  
Article
Prediction and Control of Small Deviation in the Time-Delay of the Image Tracker in an Intelligent Electro-Optical Detection System
Actuators 2023, 12(7), 296; https://doi.org/10.3390/act12070296 - 21 Jul 2023
Cited by 1 | Viewed by 762
Abstract
A small deviation in the time-delay of the image tracker is essential for improving the tracking precision of an electro-optical system, and for future advances in actuator technology. The core goal of this manuscript is to address issues such as tracking the controller [...] Read more.
A small deviation in the time-delay of the image tracker is essential for improving the tracking precision of an electro-optical system, and for future advances in actuator technology. The core goal of this manuscript is to address issues such as tracking the controller time-delay compensation and the precision of an electro-optical detection system using an advanced filter design, a fire control modeling, and an anti-occlusion target detection system. To address this problem, a small deviation in the time-delay prediction and control method of the image tracker is proposed based on the principle of linear motion transformation. The time-delay error formation is analyzed in detail to reveal the scientific mechanism between the tracking controller feedback and the line-of-sight position correction. An advanced N-step Kalman filtering controller model is established by combining a line-of-sight firing control judgment and a single-sample training anti-occlusion DSST target tracking strategy. Finally, an actuator platform with three degrees of freedom is used to test the optical mechatronics system. The results show that the distribution probability of the line-of-sight measuring error in a circle with a radius of 0.15 mrad is 72%. Compared with the traditional control method, the tracking precision of the optimal method is improved by 58.3%. Full article
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13 pages, 6932 KiB  
Article
Electromagnetic Design and Analysis of Inertial Mass Linear Actuator for Active Vibration Isolation System
Actuators 2023, 12(7), 295; https://doi.org/10.3390/act12070295 - 20 Jul 2023
Cited by 1 | Viewed by 1066
Abstract
Underwater radiated noise from anthropogenic structures must be reduced to protect the marine environment. Active vibration isolation that can reduce noise generated from vibration sources by providing counteracting forces can solve this issue. This paper presents a 120 N class electromagnetic inertial mass [...] Read more.
Underwater radiated noise from anthropogenic structures must be reduced to protect the marine environment. Active vibration isolation that can reduce noise generated from vibration sources by providing counteracting forces can solve this issue. This paper presents a 120 N class electromagnetic inertial mass linear actuator for an active vibration control system in a large ship. The proposed actuator is operated based on the Lorentz force, also known as electromagnetic force. To achieve a high thrust force to weight ratio, a permanent magnet with outer radial magnetization is used. In order to design and analyze the proposed model, a simple magnetic equivalent circuit analysis was first conducted to achieve an appropriate force, and its value was compared and verified with the magnetostatic finite element method. The dynamic characteristics of the actuator were then evaluated, and the performance was analyzed at various operating frequency points. The bobbin housing supporting the coil causes an eddy current loss due to materials with electrical conductivity. As a result, the damping force is generated by the reduction in magnetic flux, and the control force tends to decrease. Full article
(This article belongs to the Section High Torque/Power Density Actuators)
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16 pages, 5072 KiB  
Article
A Preliminary Virtual Study on the Feasibility of Transferring Muscular Activation Pattern Behaviors of Psychomotor Exercises
Actuators 2023, 12(7), 294; https://doi.org/10.3390/act12070294 - 19 Jul 2023
Viewed by 1128
Abstract
Research has demonstrated that Taekwondo training helps to enhance the coordination capabilities in people with developmental coordination disorders. These excellent results depend on many factors, including the behavior of the muscular activation patterns of psychomotor exercises during Taekwondo training. Our basic idea is [...] Read more.
Research has demonstrated that Taekwondo training helps to enhance the coordination capabilities in people with developmental coordination disorders. These excellent results depend on many factors, including the behavior of the muscular activation patterns of psychomotor exercises during Taekwondo training. Our basic idea is to study the behavior of the muscular activation pattern of Taekwondo training (performed by athletes) and to apply the adapted behavior of the muscular activation pattern to other subjects with reduced coordination capabilities to enhance them, in line with the sustainable human development goals. This paper presents a preliminary feasibility study and a first step in this direction using a virtual simulation. First, the Taekwondo front-kick exercise was studied and reproduced using a virtual human model in OpenSim. Second, some perturbations were applied to the virtual human model to analyze the behavior of the muscular activation patterns. Third, functional electrical stimulation (FES) patterns were properly simulated to reproduce the same sequence (and value) of signals of muscular activation in another subject. The proposed methodology was conceived on the basis of a simple example of a Taekwondo kick by using a virtual human model, but its general application can fit all kinds of psychomotor exercises. If future works confirm the simulation results presented in this paper with real implementation, the methodology proposed here could be applied every time human capabilities must be increased with or without sports training (e.g., remaining seated on a chair or lying on a bed). Full article
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22 pages, 17504 KiB  
Article
A Large Force Haptic Interface with Modular Linear Actuators
Actuators 2023, 12(7), 293; https://doi.org/10.3390/act12070293 - 18 Jul 2023
Viewed by 1168
Abstract
This paper presents a haptic interface with modular linear actuators that addresses the limitations of conventional devices based on rotary joints. The proposed haptic interface is composed of parallel linear actuators that provide high backdrivability and small inertia. The performance of the haptic [...] Read more.
This paper presents a haptic interface with modular linear actuators that addresses the limitations of conventional devices based on rotary joints. The proposed haptic interface is composed of parallel linear actuators that provide high backdrivability and small inertia. The performance of the haptic interface is compared to those of conventional mechanisms in terms of force capability, reflected inertia, and structural stiffness. High stiffness, large range of motion, and high force capability, which are in trade-off relationships in traditional haptic interfaces, are achieved. The device can apply up to 83 N continuously, i.e., three-fold more than most haptic devices. The theoretical minimum haptic force density and stiffness of the proposed mechanism are 1.3 to 1.9 and 37 times those of the conventional mechanisms under similar conditions, respectively. The system is scalable because the structural stiffness depends on only the timing belt stiffness, whereas that of conventional haptic interfaces is inversely proportional to the cube of the structural length. The modular actuator enables changes in the degrees of freedom (DOFs) for different applications. The proposed haptic interface was tested through an interaction experiment in a virtual environment with virtual walls. Full article
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17 pages, 5342 KiB  
Article
Design and Analysis of a Novel Actuator with a Double-Roller Gear Drive
Actuators 2023, 12(7), 292; https://doi.org/10.3390/act12070292 - 18 Jul 2023
Viewed by 1393
Abstract
In recent years, with the development of robot transmission technology, the market demand for high-performance actuators, which can be applied to lower limb exoskeleton assist robots, is increasing. These robots help achieve human–robot interaction through rigid and flexible coupling, and they can ensure [...] Read more.
In recent years, with the development of robot transmission technology, the market demand for high-performance actuators, which can be applied to lower limb exoskeleton assist robots, is increasing. These robots help achieve human–robot interaction through rigid and flexible coupling, and they can ensure the flexibility of the elderly or patients in daily walking and rehabilitation training. A novel actuator with a double-roller gear drive structure is proposed with high bearing capability and high transmission efficiency due to multi-tooth rolling contact with small tooth difference such that friction is greatly reduced in the transmission process compared to what occurs in involute planetary transmission. The bearing capacity of the tooth surface was analyzed by using the loaded contact analysis method. Finally, a prototype was manufactured with the 3D printer, and the maximum output torque of the developed actuator was tested with an experimental setup. The results show that this novel actuator, with its double-roller gear drive, has huge potential for use in the hip joint of an exoskeleton robot. Full article
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17 pages, 8958 KiB  
Article
Design and Optimization of a Permanent Magnet-Based Spring–Damper System
Actuators 2023, 12(7), 291; https://doi.org/10.3390/act12070291 - 18 Jul 2023
Cited by 1 | Viewed by 876
Abstract
This paper reports the design and optimization of a permanent magnet-based spring. The aim of the optimization, performed using a particular form of the self-organizing map (SOM) algorithm, was to determine the dimensions of a ring PM-based spring with a force–displacement curve similar [...] Read more.
This paper reports the design and optimization of a permanent magnet-based spring. The aim of the optimization, performed using a particular form of the self-organizing map (SOM) algorithm, was to determine the dimensions of a ring PM-based spring with a force–displacement curve similar to a desired one. For each step in the optimization process, a spring composed of different ring-shaped magnets was analyzed using a semi-analytical model. Its characteristic was compared with the desired one to search for a minimum cost function obtained by subtracting the evaluated and the desired force–displacement curve. The resulting algorithm was efficient in the design of a spring with a desired characteristic. The geometry obtained was used to study an electrodynamic damper based on the exploitation of the interaction between the moving magnet of the spring and a conductive cylinder. A parametric analysis was performed: the damping effect grows when the cylinder thickness increases and decreases with the gap between the cylinder and the magnets. Also, the cylinder thickness needed to reduce to one the number of overshoots in the moving magnet’s position decreases with the gap increase. Computations were performed using the research code EN4EM (Electric Network 4 ElectroMagnetics) developed by the authors. Full article
(This article belongs to the Special Issue Electromagnetic Actuators)
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15 pages, 940 KiB  
Article
Comfort-Oriented Semi-Active Suspension Configuration with Inerter-Based Network Synthesis
Actuators 2023, 12(7), 290; https://doi.org/10.3390/act12070290 - 16 Jul 2023
Viewed by 953
Abstract
This paper presents a comfort-oriented semi-active suspension system composed of a network-synthesized passive section and a controllable section based on a semi-active inerter. Firstly, the semi-active suspension system is divided into a passive part and a controllable part. For the passive part, first-order [...] Read more.
This paper presents a comfort-oriented semi-active suspension system composed of a network-synthesized passive section and a controllable section based on a semi-active inerter. Firstly, the semi-active suspension system is divided into a passive part and a controllable part. For the passive part, first-order and second-order robust positive real controllers are designed. The problem with H2 cost is considered, and the bilinear matrix inequalities (BMI) are solved using an iterative method to obtain two admittance functions. The admittance functions are physically realized as two mechanical networks composed of mechanical passive elements such as inerter, spring, and damper (ISD). Then, the parameters of these mechanical elements in those networks are optimized by Particle Swarm Optimization (PSO). Secondly, a semi-active inerter based on Sky-hook control is introduced for the semi-active part of the suspension system. Finally, the semi-active ISD suspension structure is verified by a quarter vehicle model. The simulation results show that the first-order and second-order suspension systems optimize the RMS of the spring mass acceleration by 14.2% and 23.9%, respectively, as compared to traditional suspension systems. Furthermore, frequency-domain analysis also shows that both suspension systems effectively reduce the value of spring mass acceleration in the low-frequency band. Full article
(This article belongs to the Section Actuators for Land Transport)
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18 pages, 7399 KiB  
Article
Transparent Localized Haptics: Utilization of PVDF Actuators on Touch Displays
Actuators 2023, 12(7), 289; https://doi.org/10.3390/act12070289 - 16 Jul 2023
Viewed by 1070
Abstract
Generating localized haptic feedback on touch displays has been a challenge in recent years. In this study, we introduce a haptic interface using transparent thin-film PVDF actuators to address this issue. The transparency feature can be used to mount the actuators at any [...] Read more.
Generating localized haptic feedback on touch displays has been a challenge in recent years. In this study, we introduce a haptic interface using transparent thin-film PVDF actuators to address this issue. The transparency feature can be used to mount the actuators at any location beneath the display, enabling localized haptic feedback as the generated vibration is primarily evident on the mounting area. Two different configurations are designed, simulated and prepared to explore the effectiveness of the proposed approach. The first configuration is used to characterize the haptic interface. Modal and forced-vibration analyses are performed to identify important design characteristics based on human factors. Subsequent 2AFC psychophysics experiments validate the characteristics. In the second configuration, eight actuators are attached to the touch surface in a 2 × 4 matrix formation and excited at different voltage amplitudes. Human experiments are conducted based on the results from corresponding forced-vibration analysis. The results show that subjects demonstrate an accuracy of 96% in identifying locations with haptic feedback when the actuators are excited with 232 Vpp. Overall, our study demonstrates the effectiveness of the proposed transparent haptic interface equipped with PVDF actuators in achieving localized haptic feedback on touch displays. Full article
(This article belongs to the Special Issue Actuators for Haptic Feedback Applications)
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28 pages, 5604 KiB  
Article
Structural Optimization of Lightweight Composite Floors with Integrated Constrained Layer Damping for Vibration Control
Actuators 2023, 12(7), 288; https://doi.org/10.3390/act12070288 - 13 Jul 2023
Viewed by 959
Abstract
Due to current architectural trends, contemporary public buildings are becoming open-plan spaces with much less weight and damping. Consequently, Vibration Serviceability Limit State (VSLS) due to human-induced vibrations has become an increasing concern for structural engineers, especially when designing offices, hospitals, or gymnasiums. [...] Read more.
Due to current architectural trends, contemporary public buildings are becoming open-plan spaces with much less weight and damping. Consequently, Vibration Serviceability Limit State (VSLS) due to human-induced vibrations has become an increasing concern for structural engineers, especially when designing offices, hospitals, or gymnasiums. When dealing with resonant vibrations, a slight increase in the floor-damping enables decreasing considerably the vibration level. The damping strategy studied in this work is usually known in the literature as Constrained Layer Damping (CLD) and consists of a viscoelastic layer constrained between the concrete slab and the steel beam of a lightweight composite floor. In this paper, a complete structural checking methodology has been developed for analyzing all the limit states that determine the final sizing of a steel–concrete composite floor treated with CLD, including a detailed analysis of the VSLS. The methodology has been used for setting a structural optimization problem for floors with and without CLD treatments. Thus, it has been demonstrated that the integration of CLD treatments at the design stage of the building allows the development of lighter floor structures with a smaller embodied carbon (EC) footprint, especially for long-span schemes with restrictive vibration limitations. Full article
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21 pages, 7019 KiB  
Article
Linear and Nonlinear Models for Drop Simulation of an Aircraft Landing Gear System with MR Dampers
Actuators 2023, 12(7), 287; https://doi.org/10.3390/act12070287 - 13 Jul 2023
Cited by 1 | Viewed by 1304
Abstract
In this study, our focus is on the drop test simulation of an MR (Magnetorheological) damper-based main landing gear (MRMLG), aiming to explore multi-degree-of-freedom (DOF) dynamic models during aircraft landing. Three different 6-DOF dynamic models are proposed in this work, and their drop [...] Read more.
In this study, our focus is on the drop test simulation of an MR (Magnetorheological) damper-based main landing gear (MRMLG), aiming to explore multi-degree-of-freedom (DOF) dynamic models during aircraft landing. Three different 6-DOF dynamic models are proposed in this work, and their drop performances are compared with results achieved by commercial software. The proposed models include a nonlinear aircraft model (NLAM); a linearized approximated aircraft model (LAAM) linearizing from the nonlinear equations of motion in NLAM; and a fully approximated aircraft model (FAAM) which linearizes the MRMLG’s strut force model. In order to evaluate the drop performance of the aircraft landing gear system with MR dampers, a 7-DOF aircraft model incorporating the nonlinear MRMLG was formulated using RecurDyn. The principal comparative parameters are the coefficient of determination (R2) for the system response of each model with the RecurDyn model and root mean square error (RMSE), which is the ensemble of CG displacement data for each model. In addition, the ensemble of time series data is created for diverse drop scenarios, providing valuable insights into the performance of the proposed drop test models of an aircraft landing gear system featuring MR dampers. Full article
(This article belongs to the Special Issue Active, Semi-active and Passive Vibration Control)
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15 pages, 7203 KiB  
Article
Dynamic Modeling and Analysis of Spacecraft with Multiple Large Flexible Structures
Actuators 2023, 12(7), 286; https://doi.org/10.3390/act12070286 - 13 Jul 2023
Viewed by 923
Abstract
An analytical dynamic model is presented for a spacecraft with multiple large flexible structures. Based on the partial differential equations (PDEs) of the motion of the solar panel and deployable arm, the governing equations of the main-body and deployable antenna and the boundary [...] Read more.
An analytical dynamic model is presented for a spacecraft with multiple large flexible structures. Based on the partial differential equations (PDEs) of the motion of the solar panel and deployable arm, the governing equations of the main-body and deployable antenna and the boundary conditions at each end point are used to obtain the frequency and mode shapes of the system. Then, the ordinary differential equations (ODEs) of the system can be obtained from the orthogonality relations and mode shape. The influence of the deployable antenna on the frequencies and mode shapes of the spacecraft is investigated. The frequency veering and mode interchanged phenomenon are observed with the variation of the diameter of the deployable antenna. Using the ODEs, the dynamic responses of the spacecraft are calculated to study the influence of the control torque on the attitude and position of the antenna in the attitude maneuver. Full article
(This article belongs to the Special Issue Advanced Spacecraft Structural Dynamics and Actuation Control)
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15 pages, 4117 KiB  
Article
Improved Mass Flow Rate Regulation Methods Based on Variable Frequency Control: A Case Study of Oxidizer Agent Weighing for Solid Propellants
Actuators 2023, 12(7), 285; https://doi.org/10.3390/act12070285 - 13 Jul 2023
Viewed by 816
Abstract
The feeding and weighing of oxidizer agents is the key process of solid rocket motor propellant preparation, and its accuracy directly affects the burning performance of solid rocket motors. At present, the existing multi-batch feeding methods have the problem of low accuracy and [...] Read more.
The feeding and weighing of oxidizer agents is the key process of solid rocket motor propellant preparation, and its accuracy directly affects the burning performance of solid rocket motors. At present, the existing multi-batch feeding methods have the problem of low accuracy and high time consumption of the oxidizer agent. In this paper, an improved mass flow rate regulation method based on variable frequency control is proposed to improve accuracy and reduce time consumption. The nonlinear variation process of the mass flow rate during the opening and closing process of the air-operated pinch valve is analyzed. The periodic opening and closing frequency of the air-operated pinch valve is introduced to establish the mathematical model of the mass flow rate and frequency, and then, the model parameters are obtained through the discrete element method. The plan of the method of variable frequency regulation and the frequency parameters were determined using the multi-objective optimization method. The experiments are carried out, and the results show that compared to the existing multi-batch feeding method, optimized with the improved mass flow rate regulation methods based on the variable frequency control method, improved the feeding and weighing accuracy by 0.37% and reduced time consumption by 25.6%. Full article
(This article belongs to the Section Aircraft Actuators)
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16 pages, 3490 KiB  
Article
Periodic Disturbance Compensation Control of a Rope-Driven Lower Limb Rehabilitation Robot
Actuators 2023, 12(7), 284; https://doi.org/10.3390/act12070284 - 12 Jul 2023
Cited by 1 | Viewed by 839
Abstract
In order to solve the external periodic disturbance and unknown dynamics influence in the passive rehabilitation process of a rope-driven lower limb rehabilitation robot, a control method with periodic repeated learning was designed. In this control method, the closed-loop dynamics are divided into [...] Read more.
In order to solve the external periodic disturbance and unknown dynamics influence in the passive rehabilitation process of a rope-driven lower limb rehabilitation robot, a control method with periodic repeated learning was designed. In this control method, the closed-loop dynamics are divided into a periodic disturbance term, an unknown dynamics term, and a basic term, and the shape function is designed by using the Stone–Weirstrass theorem. In the process of periodic operation, the estimated value of the shape function coefficient is repeatedly learned to obtain the periodic disturbance term approximation and to realize the compensation in advance. Through the design of the impedance learning rate, the unknown dynamic term is periodically learned, and the unknown dynamics approximation is obtained. By combining the two approximations with the basic terms which can be solved directly, the external periodic disturbance is compensated for in advance and the control precision is improved. The control algorithm was verified by simulation, and the error fluctuation of the system gradually decreases and reaches the ideal value within several cycles. The performance of the control system is stable, and the problem of limb impedance caused by different patients is well solved. Full article
(This article belongs to the Section Control Systems)
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19 pages, 14341 KiB  
Article
Tele-Guidance of a Soft Magnetic Microrobot Transported by a Fluid in a Vascular Network
Actuators 2023, 12(7), 283; https://doi.org/10.3390/act12070283 - 12 Jul 2023
Viewed by 1057
Abstract
Electromagnetic actuation represents a novel wireless control approach utilized for the manipulation of magnetic microrobots, particularly in the context of diverse minimally invasive therapeutic applications. This study presented contributions relating to the integration of a human operator into the control system of an [...] Read more.
Electromagnetic actuation represents a novel wireless control approach utilized for the manipulation of magnetic microrobots, particularly in the context of diverse minimally invasive therapeutic applications. This study presented contributions relating to the integration of a human operator into the control system of an electromagnetic actuation framework through haptic assistance. The intervention of a human operator serves multiple purposes, encompassing the safe piloting of the microrobot during the procedure and the utilization of the doctor’s expertise. Consequently, this human-in-the-loop approach not only ensures heightened safety but also enhances public acceptability, particularly in the realm of drug delivery within the human body. To facilitate these objectives, a haptic device was proposed to propel and orient the microrobots within blood vessels, thereby enabling their targeted delivery. Additionally, a novel magnetic guidance strategy was introduced, relying on the utilization of two magnetic forces to simplify and optimize the guidance process. The electromagnetic actuation system, developed in our research laboratory, offers a comprehensive workspace that has been obtained through analytical and quantitative modeling of the magnetic field generated by the system. With an accessible workspace encompassing a cubic volume of 70 mm in length, the system facilitates easy access from all four lateral sides. Such an architectural design allows for efficient manipulation of microparticles within a significantly larger 3D workspace, surpassing the limitations imposed by traditional systems primarily confined to a small central area, as observed in existing literature. Experimental evaluations encompassing both 2D and 3D scenarios were conducted to validate the efficacy of the magnetic navigation platform. Full article
(This article belongs to the Special Issue Electromagnetic Actuators)
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12 pages, 333 KiB  
Review
A Survey of Optimal Control Allocation for Aerial Vehicle Control
Actuators 2023, 12(7), 282; https://doi.org/10.3390/act12070282 - 11 Jul 2023
Viewed by 1015
Abstract
In vehicle control, control allocation is often used to abstract control variables from actuators, simplifying controller design and enhancing performance. Surveying available literature reveals that explicit solutions are restricted to strong assumptions on the actuators, or otherwise fail to exploit the capabilities of [...] Read more.
In vehicle control, control allocation is often used to abstract control variables from actuators, simplifying controller design and enhancing performance. Surveying available literature reveals that explicit solutions are restricted to strong assumptions on the actuators, or otherwise fail to exploit the capabilities of the actuator constellation. A remedy is to formulate hierarchical minimization problems that take into account the limits of the actuators at the expense of a longer computing time. In this paper, we compared the most common norms of the objective functions for linear or linearized plants, and show available numeric solver types. Such a comparison has not been found in the literature before and indicates that some combinations of linear and quadratic norms are not sufficiently researched. While the bulk of the review is restricted to control-affine plant models, some extensions to dynamic and nonlinear allocation problems are shown. For aerial vehicles, a trend toward linearized incremental control schemes is visible, which forms a compromise between real-time capabilities and the ability to resolve some nonlinearities common in these vehicles. Full article
(This article belongs to the Special Issue Fault-Tolerant Control for Unmanned Aerial Vehicles (UAVs))
23 pages, 775 KiB  
Article
Distributed Model Predictive Control and Coalitional Control Strategies—Comparative Performance Analysis Using an Eight-Tank Process Case Study
Actuators 2023, 12(7), 281; https://doi.org/10.3390/act12070281 - 10 Jul 2023
Cited by 1 | Viewed by 954
Abstract
Complex systems composed of multiple interconnected sub-systems need to be controlled with specialized control algorithms. In this paper, two classes of control algorithms suitable for such processes are presented. Firstly, two distributed model predictive control (DMPC) strategies with different formulations are described. Afterward, [...] Read more.
Complex systems composed of multiple interconnected sub-systems need to be controlled with specialized control algorithms. In this paper, two classes of control algorithms suitable for such processes are presented. Firstly, two distributed model predictive control (DMPC) strategies with different formulations are described. Afterward, a coalitional control (CC) strategy is proposed, with two different communication topologies, i.e., a default decentralized topology and a distributed topology. All algorithms were tested on the same simulation setup consisting of eight water tanks. The simulation results show that the coalitional control methodology has a similar performance to the distributed algorithms. Moreover, due to its simplified formulation, the former can be easily tested on embedded systems with limited computation storage. Full article
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16 pages, 2115 KiB  
Article
Incremental Nonlinear Control for Aeroelastic Wing Load Alleviation and Flutter Suppression
Actuators 2023, 12(7), 280; https://doi.org/10.3390/act12070280 - 09 Jul 2023
Viewed by 2035
Abstract
This paper proposes an incremental nonlinear control method for an aeroelastic system’s gust load alleviation and active flutter suppression. These two control objectives can be achieved without modifying the control architecture or the control parameters. The proposed method has guaranteed stability in the [...] Read more.
This paper proposes an incremental nonlinear control method for an aeroelastic system’s gust load alleviation and active flutter suppression. These two control objectives can be achieved without modifying the control architecture or the control parameters. The proposed method has guaranteed stability in the Lyapunov sense and also has robustness against external disturbances and model mismatches. The effectiveness of this control method is validated by wind tunnel tests of an active aeroelastic parametric wing apparatus, which is a typical wing section containing heave, pitch, flap, and spoiler degrees of freedom. Wind tunnel experiment results show that the proposed nonlinear incremental control can reduce the maximum gust loads by up to 46.7% and the root mean square of gust loads by up to 72.9%, while expanding the flutter margin by up to 15.9%. Full article
(This article belongs to the Special Issue From Theory to Practice: Incremental Nonlinear Control)
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17 pages, 9667 KiB  
Article
Research on the Vibration Reduction Mechanism of a New Tensioning Platform with an Embedded Superstructure
Actuators 2023, 12(7), 279; https://doi.org/10.3390/act12070279 - 08 Jul 2023
Viewed by 879
Abstract
Aiming at the problem of precision driving and vibration suppression for sensitive payloads on-orbit, this paper proposes a new compliant platform based on an embedded superstructure and a smart material actuator. Firstly, the main structure of the platform is designed and optimized to [...] Read more.
Aiming at the problem of precision driving and vibration suppression for sensitive payloads on-orbit, this paper proposes a new compliant platform based on an embedded superstructure and a smart material actuator. Firstly, the main structure of the platform is designed and optimized to achieve the expected indicators via the response surface method. Then, the vibration reduction mechanism of the platform with the embedded superstructure is studied by establishing an equivalent model. Following that, a four-phase superstructure is matched and designed with a compact space, and the results are verified by finite element modal analysis. Finally, both the tensioning performance and vibration reduction performance under fixed frequency harmonic disturbance are studied via transient dynamic simulation. Based on the obtained results, directions for future improvements are proposed. The relevant conclusions can provide a reference for function integration of precision tensioning and vibration suppression. Full article
(This article belongs to the Special Issue Recent Developments in Precision Actuation Technologies)
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14 pages, 5068 KiB  
Article
Modelling the Periodic Response of Micro-Electromechanical Systems through Deep Learning-Based Approaches
Actuators 2023, 12(7), 278; https://doi.org/10.3390/act12070278 - 07 Jul 2023
Viewed by 894
Abstract
We propose a deep learning-based reduced order modelling approach for micro- electromechanical systems. The method allows treating parametrised, fully coupled electromechanical problems in a non-intrusive way and provides solutions across the whole device domain almost in real time, making it suitable for design [...] Read more.
We propose a deep learning-based reduced order modelling approach for micro- electromechanical systems. The method allows treating parametrised, fully coupled electromechanical problems in a non-intrusive way and provides solutions across the whole device domain almost in real time, making it suitable for design optimisation and control purposes. The proposed technique specifically addresses the steady-state response, thus strongly reducing the computational burden associated with the neural network training stage and generating deep learning models with fewer parameters than similar architectures considering generic time-dependent problems. The approach is validated on a disk resonating gyroscope exhibiting auto-parametric resonance. Full article
(This article belongs to the Special Issue Actuators in 2022)
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31 pages, 7907 KiB  
Review
A Review of Recent Developments in Permanent Magnet Eddy Current Couplers Technology
Actuators 2023, 12(7), 277; https://doi.org/10.3390/act12070277 - 07 Jul 2023
Cited by 3 | Viewed by 1601
Abstract
Permanent magnet eddy current couplers (PMECCs) have the characteristics of contactless torque transmission, removal of torque ripple, smooth dynamic process, and adjustable speed, and can be used as couplings, dampers, brakes, and speed governors. Their applications in industry, vehicles, and energy fields are [...] Read more.
Permanent magnet eddy current couplers (PMECCs) have the characteristics of contactless torque transmission, removal of torque ripple, smooth dynamic process, and adjustable speed, and can be used as couplings, dampers, brakes, and speed governors. Their applications in industry, vehicles, and energy fields are gradually expanding. At the same time, the requirements for the torque density and dynamic performance of PMECCs are increasing. Therefore, a large amount of research work has focused on the fast and accurate modeling, design, and optimization of PMECCs. This paper provides a survey on the development of PMECCs technology. The main topics include the structure and classification of PMECCs, modeling methods, loss and heat transfer analysis modeling, and optimization design. In addition, this paper shows the future trends of PMECCs research. All the highlighted insights and suggestions of this review will hopefully lead to increasing efforts toward the model’s construction and the optimal design of PMECCs for future applications. Full article
(This article belongs to the Section High Torque/Power Density Actuators)
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19 pages, 14219 KiB  
Article
Research on Self-Priming Piezoelectric Microjet and Its Ejection Performance Control
Actuators 2023, 12(7), 276; https://doi.org/10.3390/act12070276 - 07 Jul 2023
Viewed by 1035
Abstract
The inkjet printing technology, based on piezoelectric microjet, realizes the high-efficiency processing of special-shaped structures, and has the advantages of high precision, high efficiency, and the ability to manufacture arbitrary complex parts. In this paper, a self-priming piezoelectric micro-jet device is proposed and [...] Read more.
The inkjet printing technology, based on piezoelectric microjet, realizes the high-efficiency processing of special-shaped structures, and has the advantages of high precision, high efficiency, and the ability to manufacture arbitrary complex parts. In this paper, a self-priming piezoelectric micro-jet device is proposed and its structure and microjet process are described. ANSYS two-phase two-way fluid-structure coupling simulation analysis is carried out, and the mechanism of the piezoelectric microjet is described in detail. The effects of voltage amplitude, input signal frequency, nozzle diameter, and oil viscosity on the ejection performance of the device are studied, and a set of effective control methods are summarized. Finally, the correctness of the piezoelectric microjet mechanism and the feasibility of the proposed self-priming piezoelectric micro-jet device are verified by experiments, and its ejection performance is tested. The experimental results are consistent with the ANSYS simulation results, which verifies the correctness of the experiment. Full article
(This article belongs to the Special Issue Piezoelectric Ultrasonic Actuators and Motors)
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20 pages, 4130 KiB  
Article
Balancing Control of an Absolute Pressure Piston Manometer Based on Fuzzy Linear Active Disturbance Rejection Control
Actuators 2023, 12(7), 275; https://doi.org/10.3390/act12070275 - 06 Jul 2023
Viewed by 888
Abstract
As an international standard pressure-measuring instrument, the absolute pressure piston manometer’s working medium is gas, so the actual working process will be affected by many internal uncertainties and external disturbances, leading to its long stability time and poor performance. In this paper, a [...] Read more.
As an international standard pressure-measuring instrument, the absolute pressure piston manometer’s working medium is gas, so the actual working process will be affected by many internal uncertainties and external disturbances, leading to its long stability time and poor performance. In this paper, a fuzzy linear active disturbance rejection control strategy (FLADRC) for absolute pressure piston manometers is proposed to address these problems. First, the characteristics of the main components are analyzed according to the actual working principle of the system to establish a theoretical model of the controlled system. Second, the corresponding linear active disturbance rejection controller (LADRC) is designed according to the model. The principle of fuzzy control is introduced to adaptively adjust the controller parameters of the LADRC in real time, which improves the disadvantages of the LADRC parameters, which are difficult to rectify and have poor immunity to disturbances due to fixed parameters, and the stability of the control method is subsequently demonstrated. Finally, a simulation model is built in the Simulink environment in MATLAB, and three different pressure operating points are selected for the corresponding experiments to make a comparative analysis with Kp, PID, and LADRC. The results show that FLADRC enables the absolute pressure piston manometer to achieve better stability and greater immunity to disturbances. This also verifies the effectiveness and feasibility of the control strategy in practical engineering applications. Full article
(This article belongs to the Special Issue New Control Schemes for Actuators)
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22 pages, 3851 KiB  
Article
LSTM-CNN Network-Based State-Dependent ARX Modeling and Predictive Control with Application to Water Tank System
Actuators 2023, 12(7), 274; https://doi.org/10.3390/act12070274 - 06 Jul 2023
Cited by 1 | Viewed by 913
Abstract
Industrial process control systems commonly exhibit features of time-varying behavior, strong coupling, and strong nonlinearity. Obtaining accurate mathematical models of these nonlinear systems and achieving satisfactory control performance is still a challenging task. In this paper, data-driven modeling techniques and deep learning methods [...] Read more.
Industrial process control systems commonly exhibit features of time-varying behavior, strong coupling, and strong nonlinearity. Obtaining accurate mathematical models of these nonlinear systems and achieving satisfactory control performance is still a challenging task. In this paper, data-driven modeling techniques and deep learning methods are used to accurately capture a category of a smooth nonlinear system’s spatiotemporal features. The operating point of these systems may change over time, and their nonlinear characteristics can be locally linearized. We use a fusion of the long short-term memory (LSTM) network and convolutional neural network (CNN) to fit the coefficients of the state-dependent AutoRegressive with the eXogenous variable (ARX) model to establish the LSTM-CNN-ARX model. Compared to other models, the hybrid LSTM-CNN-ARX model is more effective in capturing the nonlinear system’s spatiotemporal characteristics due to its incorporation of the strengths of LSTM for learning temporal characteristics and CNN for capturing spatial characteristics. The model-based predictive control (MPC) strategy, namely LSTM-CNN-ARX-MPC, is developed by utilizing the model’s local linear and global nonlinear features. The control comparison experiments conducted on a water tank system show the effectiveness of the developed models and MPC methods. Full article
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15 pages, 2553 KiB  
Article
Fabric-Based, Pneumatic Exosuit for Lower-Back Support in Manual-Handling Tasks
Actuators 2023, 12(7), 273; https://doi.org/10.3390/act12070273 - 03 Jul 2023
Viewed by 1242
Abstract
Lower-back pain (LBP) is a major cause of occupational disability and morbidity. This study investigates the effectiveness of a fabric-based pneumatic exosuit in reducing discomfort and lumbar muscle activation in healthy individuals who are performing manual-handling tasks. The suit combines the comfort of [...] Read more.
Lower-back pain (LBP) is a major cause of occupational disability and morbidity. This study investigates the effectiveness of a fabric-based pneumatic exosuit in reducing discomfort and lumbar muscle activation in healthy individuals who are performing manual-handling tasks. The suit combines the comfort of soft exosuits and the support of rigid exoskeletons. Ten healthy subjects performed a circuit of lifting tasks, simulating manual-handling work, with and without AireLevate support. We assessed the comfort levels and ease of task completion via a questionnaire after each manual-handling task. There was no difference in spinal range of motion, local discomfort, or general discomfort of activities with or without the AireLevate. There was a statistically significant reduction in muscle activation of the erector spinae at the L-5 level with AireLevate support (p < 0.02). This study demonstrates the exosuit’s ability in reducing lower-back muscle activation during manual-handling tasks, while maintaining comfort and mobility. Practitioner summary: We developed a soft exosuit which was shown to significantly reduce the muscle action of the erector muscles of the lumbar spine. In addition, participants perceived that the suit was easy to use and did not limit manual-handling tasks. Full article
(This article belongs to the Section Actuators for Robotics)
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