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Actuators
Volume 12
Issue 5
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Actuators, Volume 12, Issue 5 (May 2023) – 36 articles

Cover Story (view full-size image): The picture illustrates the FEM of a winglet equipped with two independent morphing flaps and relevant kinematics. The scope of the system is to enhance aircraft performance at specific flight regimes and enable dedicated load distribution laws to reduce the loading of the wing. The lower flap is controlled by an actuator mounted in line, while the upper flap is controlled by another actuator through a dedicated kinematic chain. Both the flaps implement a finger-like mechanism to efficiently alter the chamber. Non-linear modelling and simulation approaches proved the compliance of the design with the requirements and with the targets of the project and paved the way to the next phases of the research, that is to say, the demonstration on ground and the final flight tests. View this paper
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20 pages, 4084 KiB  
Article
Integrated Security Control for Nonlinear CPS with Actuator Fault and FDI Attack: An Active Attack-Tolerant Approach
by Li Zhao, Wei Li, Yajie Li, Nani Han and Naiqin Zheng
Actuators 2023, 12(5), 216; https://doi.org/10.3390/act12050216 - 22 May 2023
Viewed by 1018
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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14 pages, 2542 KiB  
Article
Ferroelectret Polypropylene Foam-Based Piezoelectric Energy Harvester for Different Seismic Mass Conditions
by Chandana Ravikumar and Vytautas Markevicius
Actuators 2023, 12(5), 215; https://doi.org/10.3390/act12050215 - 22 May 2023
Viewed by 1173
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/s2 force on this material, ferroelectrets generate up to 39 (µW/g/mm3) 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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27 pages, 12356 KiB  
Article
Design of Two-Degree-of-Freedom Fractional-Order Internal Model Control Algorithm for Pneumatic Control Valves
by Min Zhu, Siyuan Chen, Zihao Xu and Xueping Dong
Actuators 2023, 12(5), 214; https://doi.org/10.3390/act12050214 - 22 May 2023
Cited by 1 | Viewed by 1181
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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22 pages, 4385 KiB  
Review
Loss Determination Techniques for Piezoelectrics: A Review
by Yoonsang Park, Minkyu Choi and Kenji Uchino
Actuators 2023, 12(5), 213; https://doi.org/10.3390/act12050213 - 21 May 2023
Viewed by 1611
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 (HiPoCSTM), 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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19 pages, 5448 KiB  
Article
Numerical Study on the Heating Effect of a Spring-Loaded Actuator—Part II: Optimization Design of Heater Parameters
by Zhen Zhao, Lei Xi, Jianmin Gao, Liang Xu and Yunlong Li
Actuators 2023, 12(5), 212; https://doi.org/10.3390/act12050212 - 21 May 2023
Viewed by 1068
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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30 pages, 8235 KiB  
Article
Investigations of the Crystallographic Orientation on the Martensite Variant Reorientation of the Single-Crystal Ni-Mn-Ga Cube and Its Composites for Actuator Applications
by Wan-Ting Chiu, Motoki Okuno, Masaki Tahara, Tomonari Inamura and Hideki Hosoda
Actuators 2023, 12(5), 211; https://doi.org/10.3390/act12050211 - 20 May 2023
Cited by 4 | Viewed by 1189
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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29 pages, 9450 KiB  
Article
Microactuation of Magnetic Nanofluid Enabled by a Pulsatory Rotating Magnetic Field
by Lucian Pîslaru-Dănescu, George-Claudiu Zărnescu, Eros-Alexandru Pătroi, Rareș-Andrei Chihaia and Gabriela Telipan
Actuators 2023, 12(5), 210; https://doi.org/10.3390/act12050210 - 19 May 2023
Cited by 1 | Viewed by 1041
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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25 pages, 7694 KiB  
Article
Sliding Mode Active Disturbance Rejection Control of Permanent Magnet Synchronous Motor Based on Improved Genetic Algorithm
by Shuai Li, Henian Li, Hai Wang, Chunlai Yang, Jingsong Gui and Ronghua Fu
Actuators 2023, 12(5), 209; https://doi.org/10.3390/act12050209 - 19 May 2023
Cited by 2 | Viewed by 1140
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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25 pages, 53546 KiB  
Article
Actuation Behavior of Hydraulically Amplified Self-Healing Electrostatic (HASEL) Actuator via Dimensional Analysis
by Alexandrea Washington, Ji Su and Kwang J. Kim
Actuators 2023, 12(5), 208; https://doi.org/10.3390/act12050208 - 18 May 2023
Cited by 3 | Viewed by 1580
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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20 pages, 537 KiB  
Article
Distributed Cooperative Cruise Control for High-Speed Trains with Energy-Saving Optimization
by Feng Zhou, Kewu Tao, Bin Chen, Shuo Li, Zhengfa Zhu and Yingze Yang
Actuators 2023, 12(5), 207; https://doi.org/10.3390/act12050207 - 17 May 2023
Viewed by 1021
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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23 pages, 6749 KiB  
Article
Multi-Objective Optimal Design of μ–Controller for Active Magnetic Bearing in High-Speed Motor
by Yuanwen Li and Changsheng Zhu
Actuators 2023, 12(5), 206; https://doi.org/10.3390/act12050206 - 17 May 2023
Cited by 2 | Viewed by 1279
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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12 pages, 16589 KiB  
Article
Evaluation of Spiral Pneumatic Rubber Actuator Using Finite Element Analysis for Radial Transportation
by Yujin Jang, Hiroyuki Nabae and Koichi Suzumori
Actuators 2023, 12(5), 205; https://doi.org/10.3390/act12050205 - 17 May 2023
Viewed by 1122
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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19 pages, 9996 KiB  
Article
Analysis of the Antagonistic Arrangement of Pneumatic Muscles Inspired by a Biological Model of the Human Arm
by Peter Tuleja, Rudolf Jánoš, Ján Semjon, Marek Sukop and Peter Marcinko
Actuators 2023, 12(5), 204; https://doi.org/10.3390/act12050204 - 17 May 2023
Cited by 1 | Viewed by 1178
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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25 pages, 6342 KiB  
Article
Research on Magnetic Characteristics and Fuzzy PID Control of Electromagnetic Suspension
by Wei Wei, Songjian Yu and Baozuo Li
Actuators 2023, 12(5), 203; https://doi.org/10.3390/act12050203 - 17 May 2023
Cited by 1 | Viewed by 1219
Abstract
This paper proposes an electromagnetic suspension with an electromagnetic actuator, which can improve the riding comfort and stability of the vehicle without changing the safety of traditional MacPherson suspension. First, the electromagnetic suspension structure is introduced, and the principle of the proposed actuator [...] Read more.
This paper proposes an electromagnetic suspension with an electromagnetic actuator, which can improve the riding comfort and stability of the vehicle without changing the safety of traditional MacPherson suspension. First, the electromagnetic suspension structure is introduced, and the principle of the proposed actuator is described in detail. Second, a magnetic flux density model of a single PM ring (permanent magnetic ring) and a magnet assembly are built, and a theoretical analysis of the magnetic flux density is carried out for comparison. Then, the magnetic flux distribution of the magnetic field is simulated and analyzed using the finite element method (FEM), and is compared with theoretical and other experimental data. Finally, a vehicle dynamics model with 7 DOF is built, and vehicle simulations based on the fuzzy PID algorithm are carried out on a C-grade road surface and a deceleration strip. The theoretical results and simulation analyses of the FEM indicate that compared with the MacPherson suspension, the root mean square values of the acceleration of centroid acceleration for the electromagnetic suspension are increased by 59.08% and 33.34%, respectively, on a C-grade road surface and a deceleration strip, and other physical quantities have also been improved. The structure and characteristics of the proposed electromagnetic suspension that improve the riding comfort of the suspension and enhance the stability of the MacPherson suspension are feasible. Full article
(This article belongs to the Special Issue Advanced Technologies on the Control Method of Electromagnetic Actuator)
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18 pages, 8353 KiB  
Article
Development of a Deformable Water-Mobile Robot
by Changlong Ye, Yang Su, Suyang Yu and Yinchao Wang
Actuators 2023, 12(5), 202; https://doi.org/10.3390/act12050202 - 12 May 2023
Cited by 2 | Viewed by 1218
Abstract
This article proposes a deformable water-mobile robot that can be used for rescue work. The robot body adopts an open-motion chain structure with two degrees of freedom, including two drive modules and one main control module. The three modules are connected through deformation [...] Read more.
This article proposes a deformable water-mobile robot that can be used for rescue work. The robot body adopts an open-motion chain structure with two degrees of freedom, including two drive modules and one main control module. The three modules are connected through deformation joints, and each drive module is equipped with an underwater thruster. The robot can obtain a triangle, linear shape, curved shape, and U-shape through deformation and have three types of motion: linear shape motion, U-shaped motion, and curved shape motion. In the linear shape, a multi-island genetic algorithm was used to optimize the structural parameters with the minimum resistance and the maximum volume. Floating state analysis was conducted in the U-shape, and the structural parameters were reasonably designed. By experimenting with the robot prototype on water, the robot can achieve oscillating, linear, U-shaped, and horizontal rotary motion, has an automatic adjustment function, and effective buoyancy meets the required requirements. Full article
(This article belongs to the Special Issue Modeling, Optimization and Control of Robotic Systems)
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15 pages, 16694 KiB  
Article
A Novel High-Voltage-Cable Stripping Robot
by Jun Zhong, Wenxu Ai, Zhichao Wang, Shaoguang Hu and Hongshuang Zhang
Actuators 2023, 12(5), 201; https://doi.org/10.3390/act12050201 - 12 May 2023
Viewed by 1329
Abstract
One of the primary duties in the regular maintenance of electrical distribution networks is the cable stripping operation. In this paper, a unique robot is proposed to overcome drawbacks of the conventional manual operation of cable stripping, such as poor efficiency, low safety, [...] Read more.
One of the primary duties in the regular maintenance of electrical distribution networks is the cable stripping operation. In this paper, a unique robot is proposed to overcome drawbacks of the conventional manual operation of cable stripping, such as poor efficiency, low safety, and high labor intensity. This innovative cable-stripping robot is made up of a rotating mechanism, a cable gripping component, and a cutter feeding mechanism that can be adjusted depending on the working environment and workload. The robot’s motors, sensors, main control chip, and wireless communication modules are all carefully selected. A carefully designed cascade controller is created for the robot in an effort to lessen damage to the aluminum core. While the outside location loop uses the PID algorithm, the inner speed control loop uses fuzzy PID. The robot can successfully accomplish cable stripping work and demonstrates its potential to reduce labor intensity. Cable stripping experiments are conducted to validate the effect of the robot and its controller. Full article
(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)
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23 pages, 1342 KiB  
Article
Dynamic Model of a Novel Planar Cable Driven Parallel Robot with a Single Cable Loop
by Antonio González-Rodríguez, Andrea Martín-Parra, Sergio Juárez-Pérez, David Rodríguez-Rosa, Francisco Moya-Fernández, Fernando J. Castillo-García and Jesús Rosado-Linares
Actuators 2023, 12(5), 200; https://doi.org/10.3390/act12050200 - 12 May 2023
Cited by 3 | Viewed by 1793
Abstract
Cable-Driven Parallel Robots (CDPRs) are a special kind of parallel manipulator that uses cables to control the position and orientation of the mobile platform or end effector. The use of cables instead of rigid links offers some advantages over their conventional rigid counterparts. [...] Read more.
Cable-Driven Parallel Robots (CDPRs) are a special kind of parallel manipulator that uses cables to control the position and orientation of the mobile platform or end effector. The use of cables instead of rigid links offers some advantages over their conventional rigid counterparts. As cables can only pull but not push, the number of cables (n) required to command the end-effector is always n+1. This configuration is known as fully-constrained, and it is the most extended configuration for CDPRs. Although CDPRs have many advantages, such as their ability to cover large working areas, one of their main problems is that their working area (workspace) is limited in comparison to its frame area (planar case) or frame volume (spatial case), due to the minimum and maximum allowed tensions. Depending on these tension values, the workspace can notoriously decrease. In order to tackle this problem, lots of works focus on solving kinematics or dynamics problems for cable sagging, i.e., they take into account sagging when modelling the robot kinematic and include these poses inside the usable robot workspace. Taking into account phenomena such as this increases the mathematical complexity of the problem, and much more complex techniques are required. On the other hand, the lack of workspace problem can be tackled by adding active or passive elements to the robot design. In this sense, this paper proposes two mechanical modifications: to add passive carriages to the robot frame and to use a single cable loop to command the end-effector position and orientation. This work presents the kinematic, static, and dynamic models of the novel design and shows the gain of workspace for a planar case while taking into account different parameters of the robot. Full article
(This article belongs to the Section Actuators for Robotics)
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17 pages, 5958 KiB  
Article
A Lightweight Exoskeleton Force Feedback Glove
by Shigang Peng, Meng Yu, Xinyu Geng, Xiang Cheng and Pengfei Wang
Actuators 2023, 12(5), 199; https://doi.org/10.3390/act12050199 - 12 May 2023
Cited by 1 | Viewed by 1763
Abstract
The wearable force feedback glove provides a promising solution for enhancing immersion during teleoperation. In this study, a lightweight five-finger exoskeleton force feedback glove (EFFG) was designed, enabling driving force detection and flexible force feedback. This wireless prototype weighs only 278 g. The [...] Read more.
The wearable force feedback glove provides a promising solution for enhancing immersion during teleoperation. In this study, a lightweight five-finger exoskeleton force feedback glove (EFFG) was designed, enabling driving force detection and flexible force feedback. This wireless prototype weighs only 278 g. The glove features a bionic structure and optimized linkage length to ensure operator safety while providing extensive coverage of the finger working space. Moreover, a detailed illustration of the kinematic and dynamic analyses, as well as the circuit structure, was presented. With this prototype as the basis, an isomorphic teleoperation system is designed to achieve force feedback during teleoperation. Concurrently, a driving force-based impedance controller was proposed to enable smooth and precise force feedback. Finally, the performance of the EFFG prototype was evaluated in both unconstrained and constrained environments, demonstrating that the proposed glove is lightweight, capable of detecting driving force, and provides flexible force feedback. Full article
(This article belongs to the Special Issue Wearable E-Textile Technologies: Sensors, Actuators, and Integrated Systems)
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23 pages, 7508 KiB  
Article
Analysis and Optimization of Motion Coupling for the Coordinated Operation of Flexible Multi-Arm Space Robots
by Guangtang Pan, Qingxuan Jia, Gang Chen, Yifan Wang and Fenglei Sun
Actuators 2023, 12(5), 198; https://doi.org/10.3390/act12050198 - 11 May 2023
Viewed by 1026
Abstract
This paper presents a novel approach for analyzing and optimizing motion coupling in the coordinated operation tasks of flexible space multi-arm robots (FMSRs). The method integrates motion coupling between multiple arms and system stiffness to improve the motion and force accuracy of FMSRs [...] Read more.
This paper presents a novel approach for analyzing and optimizing motion coupling in the coordinated operation tasks of flexible space multi-arm robots (FMSRs). The method integrates motion coupling between multiple arms and system stiffness to improve the motion and force accuracy of FMSRs by optimizing the configuration. First, a comprehensive model of an FMSR is established using the hypothetical modal method. Then, the motion coupling relationship among multiple arms is analyzed, and a motion coupling degree evaluation index is developed. Furthermore, the constraint relationship of coordinated operation is analyzed, and an equivalent stiffness model for the coordinated operation of the FMSR is formulated along with a stiffness evaluation index. Based on these analyses, the motion trajectory of the FMSR is optimized by comprehensively considering both the motion coupling degree and the equivalent stiffness factors. Finally, numerical simulation experiments are conducted to validate the proposed method, and the results show that the accuracy of the FMSR can be improved by 40% using this approach. Full article
(This article belongs to the Section Actuators for Robotics)
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26 pages, 34661 KiB  
Article
Event-Triggered Fault Estimation and Fault Tolerance for Cyber-Physical Systems with False Data Injection Attacks
by Yunji Li, Wenzhuo Zhou and Yajun Wu
Actuators 2023, 12(5), 197; https://doi.org/10.3390/act12050197 - 10 May 2023
Viewed by 1144
Abstract
This paper investigates an event-triggered framework for addressing fault estimation and fault tolerance issues in discrete-time cyber-physical systems (CPSs) with partial state saturations and random false data injection attacks (FDIAs). A stochastic variable is introduced to characterize the random FDIAs and to establish [...] Read more.
This paper investigates an event-triggered framework for addressing fault estimation and fault tolerance issues in discrete-time cyber-physical systems (CPSs) with partial state saturations and random false data injection attacks (FDIAs). A stochastic variable is introduced to characterize the random FDIAs and to establish the corresponding model. A reduced-order fault estimator and an event condition are co-derived to reconstruct system states and actuator faults. The proposed event-triggered transmission scheme helps reduce network utilization in the sensor-to-estimator channel. A sufficient condition for the proposed event-triggered estimator is derived, which minimizes state and fault estimation errors even when the controlled plants are subject to exogenous disturbances, fault signals, and random attacks. Furthermore, a fault-tolerant compensation controller is proposed using the estimated states and faults, ensuring that the considered systems achieve mean-squared stability. Finally, a DC motor platform is developed to further demonstrate the effectiveness of the designed estimator-based fault-tolerant controller. Full article
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24 pages, 6546 KiB  
Article
Characterization of an Antagonistic Actuation System with Nonlinear Compliance for an Upper-Arm Exoskeleton
by Max Jäger, Thomas Helbig, Moritz Goos, Sebastian Köhring and Hartmut Witte
Actuators 2023, 12(5), 196; https://doi.org/10.3390/act12050196 - 10 May 2023
Cited by 1 | Viewed by 1666
Abstract
The parallel connection of technical and biological systems with a comparable mechanical behavior offers the possibility of reducing the interaction forces between those systems. Especially in the context of human–robot interaction (e.g., exoskeletons), it can improve user safety and acceptance at the same [...] Read more.
The parallel connection of technical and biological systems with a comparable mechanical behavior offers the possibility of reducing the interaction forces between those systems. Especially in the context of human–robot interaction (e.g., exoskeletons), it can improve user safety and acceptance at the same time. With this aim, we used antagonistic actuators with nonlinear compliance for a modular upper-extremity exoskeleton following biological paragons, mirroring the “blueprint” of its human user. In a test-bed setup, we compared antagonistic compliant actuation with antagonistic stiff, unilateral stiff and unilateral compliant actuation in the artificial “elbow joint” of the exoskeleton test bed. We show that this type of actuation allows the variation of the joint stiffness during motion, independent of the position. With the approach we propose, compliance leads to reduced force peaks and angular jerk, without sacrifices in terms of time constants and overshoot of amplitudes. We conclude that the presented actuation principle has considerable benefits in comparison to other types of exoskeleton actuation, even when using only commercially available and 3D printed components. Based on our work, further investigations into the control of compliant antagonistically actuated exoskeletons become realizable. Full article
(This article belongs to the Special Issue Actuators and Robots for Biomedical Applications)
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17 pages, 5229 KiB  
Article
Contribution to Improve Magnetic Performance and Torque Ripple Reduction of the Low-Speed DSPM Machine
by Tarek Kendjouh, Cherif Guerroudj, Jean-Frédéric Charpentier, Nicolas Bracikowski, Larbi Hadjout and Lemnouer Bekhouche
Actuators 2023, 12(5), 195; https://doi.org/10.3390/act12050195 - 09 May 2023
Viewed by 1360
Abstract
This article deals with the performance improvement of a toothed pole variable reluctance machine excited by permanent magnets housed in the stator yoke. The objective was to reduce the electromagnetic torque ripples caused by the structure geometry and by the supply technique. The [...] Read more.
This article deals with the performance improvement of a toothed pole variable reluctance machine excited by permanent magnets housed in the stator yoke. The objective was to reduce the electromagnetic torque ripples caused by the structure geometry and by the supply technique. The machine was designed to meet the specifications of a small wind energy conversion system. The proposed solution improved the electromagnetic design of the new structure in order to minimize the variation of the reluctance. This improvement was obtained by action on the geometry of the structure (the location of the permanent magnets), by action on the stator and rotor tooth pitch, and by the application of an indirect control strategy called torque sharing function. The PSO optimization algorithm was applied in the first part for the optimization of the machine’s global parameters to maximize torque density and then, in the second part, for the research of the optimum tooth pitch parameters to minimize torque ripple. Static and dynamic performances were obtained using 2D-FEM and MATLAB/Simulink software. The results reveal that by action on the stator/rotor tooth pitch, the ripple torque was reduced by about 53%, and by approximately 76% with the used command technique. Full article
(This article belongs to the Special Issue Advanced Technologies on the Control Method of Electromagnetic Actuator)
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21 pages, 10124 KiB  
Article
Kinematic Chain of a Morphing Winglet: Specifications, Conceptual and Advanced Design
by Salvatore Ameduri, Ignazio Dimino, Lorenzo Pellone, Antonio Concilio, Umberto Mercurio, Federico Gallorini, Giulio Pispola and Moreno D’Andrea
Actuators 2023, 12(5), 194; https://doi.org/10.3390/act12050194 - 09 May 2023
Viewed by 1175
Abstract
The present work focuses on the actuation system of a morphing winglet conceived to adaptively alter the load distribution on the wing, to reduce its stress level and enhance the climb performance. The winglet is equipped with two flaps, independently controlled by dedicated [...] Read more.
The present work focuses on the actuation system of a morphing winglet conceived to adaptively alter the load distribution on the wing, to reduce its stress level and enhance the climb performance. The winglet is equipped with two flaps, independently controlled by dedicated kinematic chains, in turn moved by linear electro-magnetic actuators. An interior finger-like architecture, relevant part of the actuation system, makes particularly smooth the deflections. Starting from a survey on similar applications and on the basis of the requirements at aircraft level, the specifications of the actuation system were defined. A preliminary outline of the system was thus addressed, identifying the main components, their role and their working mode. Then, the advanced design was finalized. To this scope and considering the large displacements that characterize this kind of application, a non-linear finite element approach was implemented. Both the deflection capability with and without loads and the stress level of the system were investigated. A critical overview was finally organized, comparing the achieved results with the expectations. Full article
(This article belongs to the Special Issue Actuators in 2022)
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13 pages, 5924 KiB  
Article
A Comparative Study of Two Common Pump-Controlled Hydraulic Circuits for Single-Rod Actuators
by Ahmed Imam, Mohamed Tolba and Nariman Sepehri
Actuators 2023, 12(5), 193; https://doi.org/10.3390/act12050193 - 03 May 2023
Cited by 1 | Viewed by 1415
Abstract
Pump-controlled hydraulic circuits are proven to be more efficient than conventional valve-controlled circuits. Pump-controlled hydraulic circuits for double rod cylinders are well developed and are in use in many practical applications. Existing pump-controlled circuits for single-rod actuators experience oscillation issues under specific operating [...] Read more.
Pump-controlled hydraulic circuits are proven to be more efficient than conventional valve-controlled circuits. Pump-controlled hydraulic circuits for double rod cylinders are well developed and are in use in many practical applications. Existing pump-controlled circuits for single-rod actuators experience oscillation issues under specific operating conditions; that is identified as a critical operating zone on the load-velocity plane. The challenge in these circuits is to find out the proper way to compensate for the differential flow at both sides of the cylinder in all operating conditions. The two main types of valves commonly used by researchers, to compensate for differential flow in single-rod cylinder circuits, are: pilot-operated check valves, and shuttle valves. In this research, a performance comparison between circuits equipped with either valves, in terms of the size of the critical zone and the oscillations’ characteristics, was accomplished. Simulation studies showed that the circuits that utilize pilot-operated check valves possesses smaller oscillatory zones and less severe oscillations, when compared to circuits with shuttle valves. Experimental work verified the simulation results and proved the accuracy of the mathematical models. Hence, pump-controlled circuits with pilot-operated check valves are recommended to be the basic platform for further efforts to solve the oscillation problem in pump-controlled circuits. Full article
(This article belongs to the Special Issue Actuators in 2022)
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24 pages, 13623 KiB  
Article
Data-Driven Robotic Tactile Grasping for Hyper-Personalization Line Pick-and-Place
by Zhen Xie, Josh Ye Seng Chen, Guo Wei Lim and Fengjun Bai
Actuators 2023, 12(5), 192; https://doi.org/10.3390/act12050192 - 01 May 2023
Cited by 3 | Viewed by 2675
Abstract
Industries such as the manufacturing or logistics industry need algorithms that are flexible to handle novel or unknown objects. Many current solutions in the market are unsuitable for grasping these objects in high-mix and low-volume scenarios. Finally, there are still gaps in terms [...] Read more.
Industries such as the manufacturing or logistics industry need algorithms that are flexible to handle novel or unknown objects. Many current solutions in the market are unsuitable for grasping these objects in high-mix and low-volume scenarios. Finally, there are still gaps in terms of grasping accuracy and speed that we would like to address in this research. This project aims to improve the robotic grasping capability for novel objects with varying shapes and textures through the use of soft grippers and data-driven learning in a hyper-personalization line. A literature review was conducted to understand the tradeoffs between the deep reinforcement learning (DRL) approach and the deep learning (DL) approach. The DRL approach was found to be data-intensive, complex, and collision-prone. As a result, we opted for a data-driven approach, which to be more specific, is PointNet GPD in this project. In addition, a comprehensive market survey was performed on tactile sensors and soft grippers with consideration of factors such as price, sensitivity, simplicity, and modularity. Based on our study, we chose the Rochu two-fingered soft gripper with our customized force-sensing resistor (FSR) force sensors mounted on the fingertips due to its modularity and compatibility with tactile sensors. A software architecture was proposed, including a perception module, picking module, transfer module, and packing module. Finally, we conducted model training using a soft gripper configuration and evaluated grasping with various objects, such as fast-moving consumer goods (FMCG) products, fruits, and vegetables, which are unknown to the robot prior to grasping. The grasping accuracy was improved from 75% based on push and grasp to 80% based on PointNetGPD. This versatile grasping platform is independent of gripper configurations and robot models. Future works are proposed to further enhance tactile sensing and grasping stability. Full article
(This article belongs to the Special Issue Advanced Technologies and Applications in Robotics)
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26 pages, 10932 KiB  
Article
Novel Adaptive Magnetic Springs for Reliable Industrial Variable Stiffness Actuation
by Branimir Mrak, Jeroen Willems, Jonathan Baake and Chris Ganseman
Actuators 2023, 12(5), 191; https://doi.org/10.3390/act12050191 - 30 Apr 2023
Viewed by 1377
Abstract
Parallel elastic actuation is a highly promising concept for assisting preplanned trajectories such as repetitive tasks in industrial machines and robots. Nevertheless, due to the persisting challenges on spring lifetime, its full potential has yet to be leveraged in the industry. We propose [...] Read more.
Parallel elastic actuation is a highly promising concept for assisting preplanned trajectories such as repetitive tasks in industrial machines and robots. Nevertheless, due to the persisting challenges on spring lifetime, its full potential has yet to be leveraged in the industry. We propose a novel adaptive magnetic spring as a fatigue-free spring mechanism to enable variable stiffness actuators in long lifetime applications. The spring is designed to flexibly deal with variations in operating conditions, i.e., mass customization. We propose a co-design methodology which simultaneously optimizes the sizing of the magnetic spring (for the given machine and its operating conditions), together with the controls and ideal dynamic response of the system. This mechanism and the methodology are applied to a design problem of a weaving machine drivetrain, where the benefits of the adaptive magnetic spring are highlighted with respect to a fixed stiffness magnetic spring, and the current industrial benchmark without springs. Experimentally validated findings show a consistent and considerable improvement with respect to energy consumption and peak torque reduction of up to 47% and 64%, respectively, when comparing to the current industrial benchmark. Full article
(This article belongs to the Special Issue Actuators in 2022)
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18 pages, 3858 KiB  
Article
A Computationally Efficient Hysteresis Model for Magneto-Rheological Clutches and Its Comparison with Other Models
by Zi-Qi Yang and Mehrdad R. Kermani
Actuators 2023, 12(5), 190; https://doi.org/10.3390/act12050190 - 28 Apr 2023
Cited by 1 | Viewed by 1451
Abstract
The collaborative robot market has experienced rapid growth, leading to advancements in compliant actuation and torque control. Magneto-rheological (MR) clutches offer a hardware-level solution for achieving both compliance and torque control through adjustable coupling between the input and output of the MR clutch. [...] Read more.
The collaborative robot market has experienced rapid growth, leading to advancements in compliant actuation and torque control. Magneto-rheological (MR) clutches offer a hardware-level solution for achieving both compliance and torque control through adjustable coupling between the input and output of the MR clutch. However, the presence of frequency-dependent magnetic hysteresis makes controlling the output torque challenging. In this paper, we present a comparative study of six widely used hysteresis models and propose a computationally efficient algebraic model to address the issue of hysteresis modeling and control of the output torque of rotary MR clutches. We compare the estimated torques with experimental measurements from a prototype MR clutch, to evaluate the computational complexity and accuracy of the model. Our proposed algebraic hysteresis model demonstrates superior accuracy and approximately two times less computational complexity than the Bouc–Wen model, and approximately twenty times less memory requirement than neural network-based models. We show that our proposed model has excellent potential for embedded indirect torque control schemes in systems with hysteresis, such as MR clutches and isolators. Full article
(This article belongs to the Special Issue Smart Materials for Smart Actuators and Semi-active Components)
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11 pages, 3441 KiB  
Article
Characteristic Analysis of Heterochiral TCP Muscle as a Extensile Actuator for Soft Robotics Applications
by Beau Ragland and Lianjun Wu
Actuators 2023, 12(5), 189; https://doi.org/10.3390/act12050189 - 28 Apr 2023
Viewed by 1499
Abstract
A soft actuator is an essential component in a soft robot that enables it to perform complex movements by combining different fundamental motion modes. One type of soft actuator that has received significant attention is the twisted and coiled polymer artificial muscle (TCP [...] Read more.
A soft actuator is an essential component in a soft robot that enables it to perform complex movements by combining different fundamental motion modes. One type of soft actuator that has received significant attention is the twisted and coiled polymer artificial muscle (TCP actuator). Despite many recent advancements in TCP actuator research, its use as an extensile actuator is less common in the literature. This works introduces the concept of using TCP actuators as thermal-driven extensile actuators for robotics applications. The low-profile actuator can be easily fabricated to offer two unique deformation capabilities. Results from the characterization indicate that extensile actuators, made with various rod diameters and under different load conditions, display remarkable elongation deformation. Additionally, a proof-of-concept soft-earthworm robot was developed to showcase the potential application of the extensile actuator and to demonstrate the benefits of combining different types of motion modes. Full article
(This article belongs to the Special Issue Soft Actuators and Robotics)
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20 pages, 5718 KiB  
Article
A Multi-Scale Attention Mechanism Based Domain Adversarial Neural Network Strategy for Bearing Fault Diagnosis
by Quanling Zhang, Ningze Tang, Xing Fu, Hao Peng, Cuimei Bo and Cunsong Wang
Actuators 2023, 12(5), 188; https://doi.org/10.3390/act12050188 - 27 Apr 2023
Cited by 2 | Viewed by 1368
Abstract
There are a large number of bearings in aircraft engines that are subjected to extreme operating conditions, such as high temperature, high speed, and heavy load, and their fatigue, wear, and other failure problems seriously affect the reliability of the engine. The complex [...] Read more.
There are a large number of bearings in aircraft engines that are subjected to extreme operating conditions, such as high temperature, high speed, and heavy load, and their fatigue, wear, and other failure problems seriously affect the reliability of the engine. The complex and variable bearing operating conditions can lead to differences in the distribution of data between the source and target operating conditions, as well as insufficient labels. To solve the above challenges, a multi-scale attention mechanism-based domain adversarial neural network strategy for bearing fault diagnosis (MADANN) is proposed and verified using Case Western Reserve University bearing data and PT500mini mechanical bearing data in this paper. First, a multi-scale feature extractor with an attention mechanism is proposed to extract more discriminative multi-scale features of the input signal. Subsequently, the maximum mean discrepancy (MMD) is introduced to measure the difference between the distribution of the target domain and the source domain. Finally, the fault diagnosis process of the rolling is realized by minimizing the loss of the feature classifier, the loss of the MMD distance, and maximizing the loss of the domain discriminator. The verification results indicate that the proposed strategy has stronger learning ability and better diagnosis performance than shallow network, deep network, and commonly used domain adaptive models. Full article
(This article belongs to the Special Issue Dynamics and Control of Aerospace Systems)
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17 pages, 4623 KiB  
Article
Parallel Network-Based Sliding Mode Tracking Control for Robotic Manipulators with Uncertain Dynamics
by Honggang Wu, Xinming Zhang, Linsen Song, Yufei Zhang, Chen Wang, Xiaonan Zhao and Lidong Gu
Actuators 2023, 12(5), 187; https://doi.org/10.3390/act12050187 - 27 Apr 2023
Cited by 4 | Viewed by 1362
Abstract
Robot dynamics model uncertainty and unpredictable external perturbations are important factors that influence control accuracy and stability. To accurately compensate for the dynamics model in sliding mode control (SMC), a new parallel network (PCR) is proposed in this paper. The network parallelizes the [...] Read more.
Robot dynamics model uncertainty and unpredictable external perturbations are important factors that influence control accuracy and stability. To accurately compensate for the dynamics model in sliding mode control (SMC), a new parallel network (PCR) is proposed in this paper. The network parallelizes the radial basis function and convolutional neural network, which gives it the advantage of making full use of one-dimensional data fitting results and two-dimensional data feature information, realizing the deep learning of multidimensional data and improving the model’s compensation accuracy and anti-interference ability. Meanwhile, based on the integration of adaptive control techniques and gradient descent, a new weight update algorithm is designed to realize the online learning of PCR networks under loss-free functions. Then, a new sliding mode controller (PCR-SMC) is established. The model-free intelligent control of the robot is accomplished without knowledge of the predetermined upper bounds. Additionally, the stability analysis of the control system is proved by the Lyapunov theorem. Lastly, robot tracking control simulations are performed on two trajectories. The results demonstrate the high-precision tracking performance of this controller in comparison with the RBF-SMC controller. Full article
(This article belongs to the Special Issue Modeling, Optimization and Control of Robotic Systems)
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