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Actuators, Volume 11, Issue 6 (June 2022) – 32 articles

Cover Story (view full-size image): This paper presents a novel cam-based variable stiffness actuator (VSA). It significantly differs from its counterparts in that the external load is distributed on its two motors with a small difference. It is a feasible method to improve VSA’s output power, especially in compact joints, such as rehabilitation devices. The stiffness adjustment involves a spring-balanced crank-slider mechanism with a variable-length base frame. Its tunable node is the common node for force decomposition, synthesis, stiffness adjustment, and position control by setting it as the common groove of two differential variable-pitch cams. The pitch curve synthesis method is put forward to optimize load distribution. The dual motors can work together closely in the same direction against the output load. View this paper
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14 pages, 926 KiB  
Article
Energy-Aware Model Predictive Control of Assembly Lines
by Francesco Liberati, Chiara Maria Francesca Cirino and Andrea Tortorelli
Actuators 2022, 11(6), 172; https://doi.org/10.3390/act11060172 - 20 Jun 2022
Cited by 1 | Viewed by 2078
Abstract
This paper presents a model predictive approach to the energy-aware control of tasks’ execution in an assembly line. The proposed algorithm takes into account both the need for optimizing the assembly line operations (in terms of the minimization of the total cycle time) [...] Read more.
This paper presents a model predictive approach to the energy-aware control of tasks’ execution in an assembly line. The proposed algorithm takes into account both the need for optimizing the assembly line operations (in terms of the minimization of the total cycle time) and that of optimizing the energy consumption deriving from the operations, by exploiting the flexibility added by the presence of a local source of renewable energy (a common scenario of industries that are often equipped, e.g., with photovoltaic plants) and, possibly, also exploiting an energy storage plant. The energy-related objectives we take into account refer to the minimization of the energy bill and the minimization of the peaks in the power injected and absorbed from the grid (which is desirable also from the perspective of the network operator). We propose a mixed-integer linear formulation of the optimization problem, through the use of H-infinite norms, instead of the quadratic ones. Simulation results show the effectiveness of the proposed algorithm in finding a trade-off that allows keeping at a minimum the cycle time, while saving on the energy bill and reducing peak powers. Full article
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16 pages, 4086 KiB  
Article
Electromechanical Performance of Biocompatible Piezoelectric Thin-Films
by S. Ranjan Mishra, Soran Hassani Fard, Taha Sheikh and Kamran Behdinan
Actuators 2022, 11(6), 171; https://doi.org/10.3390/act11060171 - 19 Jun 2022
Cited by 5 | Viewed by 3019
Abstract
The present study analyzed a computational model to evaluate the electromechanical properties of the AlN, BaTiO3, ZnO, PVDF, and KNN-NTK thin-films. With the rise in sustainable energy options for health monitoring devices and smart wearable sensors, developers need a scale to [...] Read more.
The present study analyzed a computational model to evaluate the electromechanical properties of the AlN, BaTiO3, ZnO, PVDF, and KNN-NTK thin-films. With the rise in sustainable energy options for health monitoring devices and smart wearable sensors, developers need a scale to compare the popular biocompatible piezoelectric materials. Cantilever-based energy harvesting technologies are seldom used in sophisticated and efficient biosensors. Such approaches only study transverse sensor loading and are confined to fewer excitation models than real-world applications. The present research analyses transverse vibratory and axial-loading responses to help design such sensors. A thin-film strip (50 × 20 × 0.1 mm) of each sample was examined under volumetric body load stimulation and time-based axial displacement in both the d31 and d33 piezoelectric energy generation modes. By collecting evidence from the literature of the material performance, properties, and performing a validated finite element study to evaluate these performances, the study compared them with lead-based non-biocompatible materials such as PZT and PMN-PT under comparable boundary conditions. Based on the present study, biocompatible materials are swiftly catching up to their predecessors. However, there is still a significant voltage and power output performance disparity that may be difficult to close based on the method of excitation (i.e., transverse, axial, or shear. According to this study, BaTiO3 and PVDF are recommended for cantilever-based energy harvester setups and axially-loaded configurations. Full article
(This article belongs to the Special Issue Multifunctional Active Materials and Structures Based Actuators)
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16 pages, 5251 KiB  
Article
Design, Development and Experimental Assessment of a Cost-Effective Bellow Pneumatic Actuator
by Goran Gregov, Tomislav Ploh and Ervin Kamenar
Actuators 2022, 11(6), 170; https://doi.org/10.3390/act11060170 - 19 Jun 2022
Cited by 5 | Viewed by 2564
Abstract
Soft pneumatic actuators offer great advantages compared to rigid ones, particularly due to their compliant nature, which allows them to adapt to uncertainties in the environment. As such, they enable human-safe interactions and are often applied to various applications, such as for example, [...] Read more.
Soft pneumatic actuators offer great advantages compared to rigid ones, particularly due to their compliant nature, which allows them to adapt to uncertainties in the environment. As such, they enable human-safe interactions and are often applied to various applications, such as for example, soft grippers or wearable devices for human motion assistance. The presented research describes the process of design, development and finally control of two cost-effective bellow pneumatic actuators. The properties of the developed devices are experimentally assessed by performing three different types of experiments. In a first instance, the testing of blocking force was performed, followed by experimental assessment of velocity-displacement characteristics, and finally, the dynamical properties for sinusoidally forced motion were examined. It was shown that the actuator can provide over 100 N force and assure a contraction ratio over 40% of its full length, with maximum velocity exceeding 60 mm/s. Experimental responses to a sinusoidally forced motion allowed establishing that no significant change due to the fatigue, creep and relaxation occur in material properties. Finally, the positioning performances of both developed devices were assessed by employing PID and LQR controllers which allowed their precise position control with fast responses and steady-state errors within the 0.2 mm margin. The performed research gives some insights into the future development of the pneumatically driven mechatronics systems used for position control. Full article
(This article belongs to the Section Actuators for Robotics)
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16 pages, 3749 KiB  
Article
Multiphysical Simulation, Model Order Reduction (ECSW) and Experimental Validation of an Active Magnetic Bearing
by Johannes Maierhofer, Christoph Dietz, Oliver M. Zobel and Daniel J. Rixen
Actuators 2022, 11(6), 169; https://doi.org/10.3390/act11060169 - 17 Jun 2022
Cited by 3 | Viewed by 1785
Abstract
Model order reduction techniques can be used during the operation phase of a product to generate virtual sensor outputs and enable diagnosis and monitoring systems. This contribution shows an approach with the example of an active magnetic bearing. The reduced model is used [...] Read more.
Model order reduction techniques can be used during the operation phase of a product to generate virtual sensor outputs and enable diagnosis and monitoring systems. This contribution shows an approach with the example of an active magnetic bearing. The reduced model is used to calculate a non-measurable physical quantity (here force) and uses a measurable quantity (temperature) to check for plausibility. As a test case, the dynamic force response under the influence of varying eddy currents due to temperature changes is investigated. Using a special test rig with a 6-dof force measurement platform, the effects are shown and the simulation results are validated. Full article
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56 pages, 5179 KiB  
Review
Biorobotics: An Overview of Recent Innovations in Artificial Muscles
by Matthew Craddock, Emmanuel Augustine, Sam Konerman and Minchul Shin
Actuators 2022, 11(6), 168; https://doi.org/10.3390/act11060168 - 17 Jun 2022
Cited by 10 | Viewed by 6452
Abstract
In this overview of recent developments in the field of biorobotics we cover the developments in materials such as the use of polyester fabric being used as artificial skin and the start of whole new ways to actuate artificial muscles as a whole. [...] Read more.
In this overview of recent developments in the field of biorobotics we cover the developments in materials such as the use of polyester fabric being used as artificial skin and the start of whole new ways to actuate artificial muscles as a whole. In this, we discuss all of the relevant innovations from the fields of nano and microtechnology, as well as in the field of soft robotics to summarize what has been over the last 4 years and what could be improved for artificial muscles in the future. The goal of this paper will be to gain a better understanding of where the current field of biorobotics is at and what its current trends in manufacturing and its techniques are within the last several years. Full article
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14 pages, 5924 KiB  
Article
A Design of Biomimetic Prosthetic Hand
by Sakura Narumi, Xiansong Huang, Jongho Lee, Hiroyuki Kambara, Yousun Kang and Duk Shin
Actuators 2022, 11(6), 167; https://doi.org/10.3390/act11060167 - 16 Jun 2022
Cited by 7 | Viewed by 4099
Abstract
Many patients with upper limb defects desire myoelectric prosthetic hands, but they are still not used for some reasons. One of the most significant reasons is its external appearance, which has the discomfort caused by the structural difference between a human hand and [...] Read more.
Many patients with upper limb defects desire myoelectric prosthetic hands, but they are still not used for some reasons. One of the most significant reasons is its external appearance, which has the discomfort caused by the structural difference between a human hand and a robotic link. The structure must be based on human anatomy to create a more natural-looking prosthesis. This study designed a biomimetic prosthetic hand with bones, ligaments, tendons, and multiple muscles based on the human musculoskeletal system. We verified the proposed prosthetic hand using the viscoelastic angle sensor to determine whether it works like a human hand. We also compared the finger force of the prosthetic hand with that of a human finger. It could be capable of controlling the angle and the stiffness of the joint by multiple extensor and flexor muscles, like humans. Full article
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14 pages, 4475 KiB  
Article
Development of a Series Elastic Tendon Actuator (SETA) Based on Gait Analysis for a Knee Assistive Exosuit
by Hee Don Lee, Heejin Park, Dae Han Hong and Tae Hun Kang
Actuators 2022, 11(6), 166; https://doi.org/10.3390/act11060166 - 15 Jun 2022
Cited by 6 | Viewed by 2625
Abstract
An exosuit is a wearable robot that assists the muscular strength of a human that wears it by using multiple wires with similar functions to human muscles. This study focuses on the development of a series elastic tendon actuator (SETA) for the actuation [...] Read more.
An exosuit is a wearable robot that assists the muscular strength of a human that wears it by using multiple wires with similar functions to human muscles. This study focuses on the development of a series elastic tendon actuator (SETA) for the actuation of an exosuit. A gait analysis was performed for walking on stairs to deduce the design requirements of SETA, and the necessary performances were then determined based on these requirements. The SETA is designed to assign compliance to rigid wires using linear springs. The deformation in linear springs generated during tension was measured through an encoder to calculate the human robot interaction (HRI) force. By utilizing the HRI force as feedback of an admittance controller, the SETA was capable of providing wire tensions required by an exosuit. The performance of the SETA was verified through series elastic component (SEC) deformation and force control experiments. The SEC deformation increased from 0 to 3.86 mm when the wire tension increased from 0 to 100 N. This force controller demonstrated a slight vibration owing to the mechanical properties of the springs constituting the SEC during the step input; however, the value gradually converged to 100 N. The developed SETA was applied to an exosuit system for supporting knee strength of the elderly when walking on stairs. Full article
(This article belongs to the Special Issue Actuation Solutions for Wearable Robots)
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17 pages, 4944 KiB  
Article
Performance Analysis of Magnetorheological Damper with Folded Resistance Gaps and Bending Magnetic Circuit
by Leping Liu, Yinan Xu, Feng Zhou, Guoliang Hu and Lifan Yu
Actuators 2022, 11(6), 165; https://doi.org/10.3390/act11060165 - 15 Jun 2022
Cited by 7 | Viewed by 2065
Abstract
The traditional magnetorheological (MR) damper subject to the limited space has shortcomings such as small damping force, narrow dynamic range and low adaptability. In this study, a new MR damper with folded resistance gaps and bending magnetic circuit was proposed for improving the [...] Read more.
The traditional magnetorheological (MR) damper subject to the limited space has shortcomings such as small damping force, narrow dynamic range and low adaptability. In this study, a new MR damper with folded resistance gaps and bending magnetic circuit was proposed for improving the damping performance. The length of the resistance gap was increased by configuring the multi-stage folded annular gap structure, and the magnetic circuit was established to activate the non-flux region. The mathematical model was established for the MR damper to analyze the damper force, magnetic circuit and dynamic performance. Subsequently, the finite element analysis (FEA) methodology was utilized to investigate the changes of magnetic flux densities in the folded resistance gaps. The test rig was setup to explore and verify the dynamic performance of the proposed MR damper under different excitation conditions. The results indicate the maximum damping force is approximately 4346 N at the current of 1.5 A, frequency of 0.25 Hz and amplitude of 7.5 mm. The damping force and dynamic range of the proposed MR damper are enhanced by 55.82% and 62.21% compared to that of the traditional MR damper at the applied current of 1.5 A, respectively, thus highlighting its high vibration control ability. Full article
(This article belongs to the Special Issue Smart Materials in Robotics and Actuators)
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20 pages, 10755 KiB  
Article
Investigation on the Opposing Jet in the Hypersonic Rarefied Flow over a Vehicle Based on the DSMC Method
by Yi Shen, Jun Zhang, Xiao Xu, Jing Liu, Zhaoming Zhang and Yanmei Jiao
Actuators 2022, 11(6), 164; https://doi.org/10.3390/act11060164 - 15 Jun 2022
Cited by 3 | Viewed by 1798
Abstract
In this paper, an opposing jet is applied to the space shuttle arc leading edge and the lifting body cone leading edge in the hypersonic condition of the rarefied flow field. The DSMC numerical algorithm is used to simulate and analyze the underlying [...] Read more.
In this paper, an opposing jet is applied to the space shuttle arc leading edge and the lifting body cone leading edge in the hypersonic condition of the rarefied flow field. The DSMC numerical algorithm is used to simulate and analyze the underlying working physics of the opposing jet. The results provide a reference for designing hypersonic vehicles in near space that reduce drag and protect against heat. Full article
(This article belongs to the Section Aircraft Actuators)
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17 pages, 4522 KiB  
Article
Sound Driven Actuator Using Helmholtz Resonance
by Takeru Niwano and Mitsuharu Matsumoto
Actuators 2022, 11(6), 163; https://doi.org/10.3390/act11060163 - 15 Jun 2022
Cited by 1 | Viewed by 1874
Abstract
Repairing cracks in the concrete of a building is very important to ensure the safety of a nuclear power plant. However, repair work in areas with very strong radiation is very difficult. Many robots have been proposed to solve this problem. However, they [...] Read more.
Repairing cracks in the concrete of a building is very important to ensure the safety of a nuclear power plant. However, repair work in areas with very strong radiation is very difficult. Many robots have been proposed to solve this problem. However, they cannot operate wirelessly and have problems such as being left as debris in the event of an accident. To solve the problem, this paper investigates the feasibility of sound-driven robots. We focused on Helmholtz resonance to achieve this goal. In this paper, Helmholtz resonators were adopted as the drive source of the actuator, and a new prototype was created by devising the arrangement. We also examined the physical characteristics of the developed prototype. Unlike conventional actuators, the proposed device can be moved remotely simply by irradiating sound from the outside. The advantage of using sound waves is that the robot can move without being affected by electric or magnetic fields. Through some experiments, it was confirmed that the developed actuator can be moved remotely with sound. Full article
(This article belongs to the Section Control Systems)
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18 pages, 15250 KiB  
Article
Research on PID Position Control of a Hydraulic Servo System Based on Kalman Genetic Optimization
by Ying-Qing Guo, Xiu-Mei Zha, Yao-Yu Shen, Yi-Na Wang and Gang Chen
Actuators 2022, 11(6), 162; https://doi.org/10.3390/act11060162 - 15 Jun 2022
Cited by 10 | Viewed by 3947
Abstract
With the wide application of hydraulic servo technology in control systems, the requirement of hydraulic servo position control performance is greater and greater. In order to solve the problems of slow response, poor precision, and weak anti-interference ability in hydraulic servo position controls, [...] Read more.
With the wide application of hydraulic servo technology in control systems, the requirement of hydraulic servo position control performance is greater and greater. In order to solve the problems of slow response, poor precision, and weak anti-interference ability in hydraulic servo position controls, a Kalman genetic optimization PID controller is designed. Firstly, aiming at the nonlinear problems such as internal leakage and oil compressibility in the hydraulic servo system, the mathematical model of the hydraulic servo system is established. By analyzing the working characteristics of the servo valve and hydraulic cylinder in the hydraulic servo system, the parameters in the mathematical model are determined. Secondly, a genetic algorithm is used to search the optimal proportional integral differential (PID) controller gain of the hydraulic servo system to realize the accurate control of valve-controlled hydraulic cylinder displacement in the hydraulic servo system. Under the positioning benchmark of step signal and sine wave signal, the PID algorithm and the genetic optimized PID algorithm are compared in the system simulation model established by Simulink. Finally, to solve the amplitude fluctuations caused by the GA optimized PID and reduce the influence of external disturbances, a Kalman filtering algorithm is added to the hydraulic servo system to reduce the amplitude fluctuations and the influence of external disturbances on the system. The simulation results show that the designed Kalman genetic optimization PID controller can be better applied to the position control of the hydraulic servo system. Compared with the traditional PID control algorithm, the PID algorithm optimized by genetic algorithm improves the system’s response speed and control accuracy; the Kalman filter is a good solution for the amplitude fluctuations caused by GA-optimized PID that reduces the influence of external disturbances on the hydraulic servo system. Full article
(This article belongs to the Special Issue Vibration Control and Structure Health Monitoring)
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18 pages, 10715 KiB  
Article
Binary Controller Based on the Electrical Activity Related to Head Yaw Rotation
by Enrico Zero, Chiara Bersani and Roberto Sacile
Actuators 2022, 11(6), 161; https://doi.org/10.3390/act11060161 - 15 Jun 2022
Viewed by 1635
Abstract
A human machine interface (HMI) is presented to switch on/off lights according to the head left/right yaw rotation. The HMI consists of a cap, which can acquire the brain’s electrical activity (i.e., an electroencephalogram, EEG) sampled at 500 Hz on 8 channels with [...] Read more.
A human machine interface (HMI) is presented to switch on/off lights according to the head left/right yaw rotation. The HMI consists of a cap, which can acquire the brain’s electrical activity (i.e., an electroencephalogram, EEG) sampled at 500 Hz on 8 channels with electrodes that are positioned according to the standard 10–20 system. In addition, the HMI includes a controller based on an input–output function that can compute the head position (defined as left, right, and forward position with respect to yaw angle) considering short intervals (10 samples) of the signals coming from three electrodes positioned in O1, O2, and Cz. An artificial neural network (ANN) training based on a Levenberg–Marquardt backpropagation algorithm was used to identify the input–output function. The HMI controller was tested on 22 participants. The proposed classifier achieved an average accuracy of 88% with the best value of 96.85%. After calibration for each specific subject, the HMI was used as a binary controller to verify its ability to switch on/off lamps according to head turning movement. The correct prediction of the head movements was greater than 75% in 90% of the participants when performing the test with open eyes. If the subjects carried out the experiments with closed eyes, the prediction accuracy reached 75% of correctness in 11 participants out of 22. One participant controlled the light system in both experiments, open and closed eyes, with 100% success. The control results achieved in this work can be considered as an important milestone towards humanoid neck systems. Full article
(This article belongs to the Special Issue Intelligent Humanoid Mobile Robots)
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19 pages, 4983 KiB  
Article
Performance-Optimized Dielectric Elastomer Actuator System with Scalable Scissor Linkage Transmission
by Daniel Bruch, Tobias Pascal Willian, Hendrik Cornelius Schäfer and Paul Motzki
Actuators 2022, 11(6), 160; https://doi.org/10.3390/act11060160 - 14 Jun 2022
Cited by 4 | Viewed by 2271
Abstract
Thanks to their outstanding properties, in the last few years Dielectric Elastomer Actuators (DEAs) have increasingly attracted the interest of the scientific community and generated a surge in the effort devoted to their industrialization. Compared to conventional actuator systems, DEAs are based on [...] Read more.
Thanks to their outstanding properties, in the last few years Dielectric Elastomer Actuators (DEAs) have increasingly attracted the interest of the scientific community and generated a surge in the effort devoted to their industrialization. Compared to conventional actuator systems, DEAs are based on inexpensive and widely available polymeric materials, which make them potentially attractive from a market perspective. However, DEA systems with a given layout and dimensions have a fixed force-stroke response that is only suitable for a specific load profile. This leads to a wide variety of designs combined with small production volumes and high costs, limiting the competitive advantage. This work addresses this issue by proposing a combination of DEA systems with compliant scissor linkage transmission mechanisms, which provide linear stroke and force scaling and simultaneously maintain performance optimization by leaving the convertible energy density of the DEA unaffected. For this purpose, three systems are designed, based on a same strip-shaped DEA combined with inclined buckled beam biasing mechanisms. Two of the systems are coupled with scissor linkages that offer transmission ratios of 3:1 and 1:3, respectively, to adapt the system to different load profiles. The system design is explained in detail, and the functional principle is validated through experiments. Full article
(This article belongs to the Special Issue Smart Dielectric Elastomer Actuator and Sensor Systems)
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13 pages, 3957 KiB  
Article
Design of a Panoramic Scanning Device Based on a Piezoelectric Ceramic Stack Actuator and Friction Transmission
by Minpeng Dai, Hao Ding, Chenwei Huang, Yi Zhu and Ming Wang
Actuators 2022, 11(6), 159; https://doi.org/10.3390/act11060159 - 13 Jun 2022
Cited by 1 | Viewed by 1986
Abstract
In view of the complex structure and inaccurate positioning capabilities of the existing panoramic scanning system, a panoramic scanning device based on a piezoelectric ceramic stack actuator and friction transmission was designed. In our model, the output displacement of the piezoelectric ceramics is [...] Read more.
In view of the complex structure and inaccurate positioning capabilities of the existing panoramic scanning system, a panoramic scanning device based on a piezoelectric ceramic stack actuator and friction transmission was designed. In our model, the output displacement of the piezoelectric ceramics is amplified by a bridge-type flexure hinge and applied to a shaft by friction to achieve panoramic scanning imaging. The mathematical model of the device was established, and the working characteristics were analyzed. The analysis demonstrated that the linear displacement increment of the shaft is a superposition. A modality simulation was performed, and the simulation results show that the designed device works normally at a frequency of 511.5 Hz. The test results indicated that the displacement of the actuator can reach 6 μm at an input voltage of 100 V. Moreover, the laser scanning results showed that the designed device can perform panoramic scanning imaging, which meets the requirements for use on the high-speed imaging system. Full article
(This article belongs to the Section Miniaturized and Micro Actuators)
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15 pages, 2644 KiB  
Article
Numerical Study of the Fish-like Robot Swimming in Fluid with High Reynolds Number: Immersed Boundary Method
by Jun Zhang, Zhichao Lv, Haobo Hua, Chunming Zhang, Haiyang Yu and Yanmei Jiao
Actuators 2022, 11(6), 158; https://doi.org/10.3390/act11060158 - 13 Jun 2022
Cited by 1 | Viewed by 1580
Abstract
Fish-like robots have been widely used in intelligent surveillance and investigation because of their high swimming efficiency and low traveling noise. Numerical simulations are usually selected to simulate the movement modes and hydrodynamic characteristics of fish-like robots during design and manufacture. However, the [...] Read more.
Fish-like robots have been widely used in intelligent surveillance and investigation because of their high swimming efficiency and low traveling noise. Numerical simulations are usually selected to simulate the movement modes and hydrodynamic characteristics of fish-like robots during design and manufacture. However, the body-fitted grid method traditionally utilized in numerical simulations often has difficulty dealing with moving solid boundaries. In this work, the immersed boundary method, superior in handling the moving boundary conditions, is employed to simulate the movement of a fish-like robot swimming in high Reynolds number flows in combination with the RANS turbulence model. The numerical method is first validated using a fluid flowing over a square block, and the corresponding results are in good agreement with the ones reported in reference. Then, the swing of the fish-like robot under three different Reynolds numbers is studied. The lift coefficient and the drag coefficient of the fish-like robot decrease with increasing the Reynolds number. This paper provides remarkable support for future designs and applications of fish-like robots. Full article
(This article belongs to the Section Actuators for Robotics)
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18 pages, 5482 KiB  
Article
Vibration Isolation Performance of an Adaptive Magnetorheological Elastomer-Based Dynamic Vibration Absorber
by Young Choi and Norman M. Wereley
Actuators 2022, 11(6), 157; https://doi.org/10.3390/act11060157 - 12 Jun 2022
Cited by 6 | Viewed by 2904
Abstract
This study evaluates the vibration isolation performance of an adaptive magnetorheological elastomer (MRE)-based dynamic vibration absorber (MRE-DVA) for mitigating the high frequency vibrations (100–250 Hz) of target devices. A simple and effective MRE-DVA design was presented and its vibration isolation performance was experimentally [...] Read more.
This study evaluates the vibration isolation performance of an adaptive magnetorheological elastomer (MRE)-based dynamic vibration absorber (MRE-DVA) for mitigating the high frequency vibrations (100–250 Hz) of target devices. A simple and effective MRE-DVA design was presented and its vibration isolation performance was experimentally measured. A cylindrical shaped MRE pad was configured to be operated in shear mode and also worked as a semi-actively tunable spring for achieving adaptive DVA. A complex stiffness analysis for the damper force cycle was conducted and it was experimentally observed that the controllable dynamic stiffness range of the MRE-DVA was greater than two over the tested frequency range. The transmissibility of a target system was measured and used as a performance index to evaluate its vibration isolation performance. It was also experimentally demonstrated that a better vibration isolation performance of the target device exposed to the high frequency vibrations could be achieved by using the adaptive MRE-DVA. Full article
(This article belongs to the Special Issue Active, Semi-active and Passive Vibration Control)
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18 pages, 2522 KiB  
Article
Control-Force Spectrum Considering Both Natural Period and Damping Ratio for Active Base-Isolated Building
by Yinli Chen, Daiki Sato, Kou Miyamoto and Jinhua She
Actuators 2022, 11(6), 156; https://doi.org/10.3390/act11060156 - 11 Jun 2022
Cited by 2 | Viewed by 1700
Abstract
The active structural control (ASC) has been applied to base-isolated buildings to achieve a high-damping system. The critical step for designing an ASC system is selecting control parameters and isolation parameters that satisfy the design restrictions. However, the conventional methods are limited in [...] Read more.
The active structural control (ASC) has been applied to base-isolated buildings to achieve a high-damping system. The critical step for designing an ASC system is selecting control parameters and isolation parameters that satisfy the design restrictions. However, the conventional methods are limited in theoretically estimating the maximum control force, which requires great demand for trial-and-error approaches and numerical simulations. This paper constructed the equivalent model of the feedback control system that theoretically expresses the dependence of vibration characteristics (natural period and damping ratio) of the control system on the feedback gain. Then, the control-force spectrum is proposed that estimates the maximum control force for a feedback control system, adjusting both the natural period and damping ratio of the control system. The maximum responses and control force are estimated without additional numerical simulations and trial-and-error approaches using the equivalent model and control-force spectrum. Moreover, a design method was devised for determining the allowance range of the vibration characteristics of structures (damping ratio and natural period) and controllers that satisfy the design limitations (maximum responses and maximum control force). The design method does not require trial-and-error and numerical simulations, thus simplifying the design procedure. Finally, this paper uses numerical examples and a design example to verify the validity of the control-force spectrum and design method. Full article
(This article belongs to the Special Issue Active, Semi-active and Passive Vibration Control)
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15 pages, 2780 KiB  
Article
Transonic Buffet Active Control with Local Smart Skin
by Kai Ren, Chuanqiang Gao, Fangqi Zhou and Weiwei Zhang
Actuators 2022, 11(6), 155; https://doi.org/10.3390/act11060155 - 10 Jun 2022
Cited by 2 | Viewed by 1861
Abstract
Transonic flight has high economic benefits, but the appearance of transonic buffet limits the flight envelope. The shock control bump currently used for transonic buffet suppression tends to degrade the aerodynamic performance of the non-buffeting state. In this study, a smart skin system [...] Read more.
Transonic flight has high economic benefits, but the appearance of transonic buffet limits the flight envelope. The shock control bump currently used for transonic buffet suppression tends to degrade the aerodynamic performance of the non-buffeting state. In this study, a smart skin system is used to eliminate the fluctuating load of transonic buffet by measuring the airfoil lift coefficient as the feedback signal and adjusting the local skin height using data-driven, model-free adaptive control. Since the actuator height is dynamically adjusted only after the occurrence of transonic buffet, the smart skin can completely suppress the fluctuating load and does not affect the aerodynamic performance in the non-buffeting state. The suppression effect of the proposed smart skin on transonic buffet is verified by numerical simulation of the flow. The simulation results show that due to the introduction of closed-loop control, the fluctuating load of transonic buffet can be effectively suppressed for different positions and maximum heights of the actuator. Even when the flow state changes, the robust smart skin system can also achieve the control goal. Therefore, smart skins combining flexible materials and control technologies have the potential to effectively improve the aerodynamic performance of aircraft. Full article
(This article belongs to the Special Issue Active Flow Control: Recent Advances in Fundamentals and Applications)
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26 pages, 4925 KiB  
Review
A Review on Thomson Coil Actuators in Fast Mechanical Switching
by Mohmmad Al-Dweikat, Jian Cui, Shuai Sun, Mingming Yang, Guogang Zhang and Yingsan Geng
Actuators 2022, 11(6), 154; https://doi.org/10.3390/act11060154 - 10 Jun 2022
Cited by 5 | Viewed by 4980
Abstract
With the rapid development of DC power systems and the increasing demand for DC circuit breakers, electromagnetic repulsive drives-based Thomson coil actuators (TCA) are widely investigated to provide the high-speed actuating required for ultra-fast mechanical switches, especially those used in hybrid DC circuit [...] Read more.
With the rapid development of DC power systems and the increasing demand for DC circuit breakers, electromagnetic repulsive drives-based Thomson coil actuators (TCA) are widely investigated to provide the high-speed actuating required for ultra-fast mechanical switches, especially those used in hybrid DC circuit breakers. The actuating mechanism is required to be fast, reliable, and economic. This article summarizes the development of Thomson coil actuators in circuit breakers in recent years, further illustrating the basic principles and the actuator topology. In addition, it discusses the various structural components of TCA and describes the utilized modeling and simulation methods. The main objective was to provide a comprehensive overview of the TCA field. Full article
(This article belongs to the Section High Torque/Power Density Actuators)
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23 pages, 6157 KiB  
Article
Design and Experiment Evaluation of Load Distribution on the Dual Motors in Cam-Based Variable Stiffness Actuator with Helping Mode
by Fanghua Mei, Shusheng Bi, Yueri Cai and Hanjun Gao
Actuators 2022, 11(6), 153; https://doi.org/10.3390/act11060153 - 8 Jun 2022
Viewed by 2081
Abstract
This paper presents a novel cam-based variable stiffness actuator (VSA). It significantly differs from its counterparts in that the external load distributes on its two motors with a small difference. It is a feasible method to improve VSA’s output power, especially in compact [...] Read more.
This paper presents a novel cam-based variable stiffness actuator (VSA). It significantly differs from its counterparts in that the external load distributes on its two motors with a small difference. It is a feasible method to improve VSA’s output power, especially in compact joints, such as rehabilitation devices. The stiffness adjustment involves a spring-balanced crank-slider mechanism with a variable-length base frame. Its tunable node is the common node for force decomposition, synthesis, stiffness adjustment, and position control by setting it at the common groove of two differential variable-pitch cams. The paper establishes analytical expressions among the pressure angle of the cam pitch curve, load distribution, and its crucial design indexes and constraints. Based on this, the pitch curve synthesis method is put forward to optimize the load distribution. In addition, a reasonable tradeoff can be easily made by locally adjusting the cam pressure angle. So, the dual motors can work against the output load together in the same direction with a close amount. In the fabricated prototype, current stratification caused by the unstable friction direction has been observed. The estimation results of motor frictionless current matched the designed load distribution behavior. Full article
(This article belongs to the Special Issue Actuation Solutions for Wearable Robots)
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9 pages, 1136 KiB  
Communication
Effect of Wearing Running Shoes on Lower Limb Kinematics by Using OpenSim Simulation Software
by Gunarajulu Renganathan, Hamidreza Barnamehei, Swagata Das and Yuichi Kurita
Actuators 2022, 11(6), 152; https://doi.org/10.3390/act11060152 - 6 Jun 2022
Cited by 7 | Viewed by 2406
Abstract
(1) Flatfoot is a common malformation in both children and adults, in which a proper arch fails to develop. This study aimed to see how over-the-counter running shoes improved the gait patterns of flatfoot patients. (2) Methods: Three healthy flatfoot subjects were included [...] Read more.
(1) Flatfoot is a common malformation in both children and adults, in which a proper arch fails to develop. This study aimed to see how over-the-counter running shoes improved the gait patterns of flatfoot patients. (2) Methods: Three healthy flatfoot subjects were included in the study. Flatfoot was diagnosed by a lateral talometatarsal angle of more than 4 degrees and a talocalcaneal angle of more than 30 degrees. All the patient data were captured using Vicon motion caption cameras. The subjects were allowed to walk at self-selected speeds with and without running shoes. (3) Results: Significant differences in lower limb kinematics were observed between barefoot and running shoe gait. In addition, by wearing the running shoes, the center of mass and lower limb kinematics changed. (4) Conclusion: The improvement in balance and control was clearly indicated, and the change in gait on the entire lower limb influenced normalizing the stresses of the foot with running shoes. These valuable results can be used for rehabilitation programs. Full article
(This article belongs to the Special Issue Soft Exoskeleton and Supernumerary Limbs for Human Augmentation)
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12 pages, 585 KiB  
Article
Data-Driven Predictive Control of Interconnected Systems Using the Koopman Operator
by Duvan Tellez-Castro, Camilo Garcia-Tenorio, Eduardo Mojica-Nava, Jorge Sofrony and Alain Vande Wouwer
Actuators 2022, 11(6), 151; https://doi.org/10.3390/act11060151 - 6 Jun 2022
Cited by 5 | Viewed by 2079
Abstract
Interconnected systems are widespread in modern technological systems. Designing a reliable control strategy requires modeling and analysis of the system, which can be a complicated, or even impossible, task in some cases. However, current technological developments in data sensing, processing, and storage make [...] Read more.
Interconnected systems are widespread in modern technological systems. Designing a reliable control strategy requires modeling and analysis of the system, which can be a complicated, or even impossible, task in some cases. However, current technological developments in data sensing, processing, and storage make data-driven control techniques an appealing alternative solution. In this work, a design methodology of a decentralized control strategy is developed for interconnected systems based only on local and interconnection time series. Then, the optimization problem associated with the predictive control design is defined. Finally, an extension to interconnected systems coupled through their input signals is discussed. Simulations of two coupled Duffing oscillators, a bipedal locomotion model, and a four water tank system show the effectiveness of the approach. Full article
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16 pages, 6626 KiB  
Article
Coupled Force–Position Control for Dynamic Contact Force Tracking in Uncertain Environment
by Xiaogang Song, Bing Li, Wenfu Xu and Zhisen Li
Actuators 2022, 11(6), 150; https://doi.org/10.3390/act11060150 - 5 Jun 2022
Viewed by 2537
Abstract
Both the position and force control of robots are needed in industrial manufacturing, such as in assembly and grinding, etc. In this paper, we concentrate on two issues. One is the system oscillation in traditional hybrid force–position control (HFPC) during switching between force [...] Read more.
Both the position and force control of robots are needed in industrial manufacturing, such as in assembly and grinding, etc. In this paper, we concentrate on two issues. One is the system oscillation in traditional hybrid force–position control (HFPC) during switching between force and position control because the diagonal elements in the selection matrix are either 0 or 1. Another issue is the poor force-tracking performance of conventional impedance control, which depends on accurate environmental models. To address these issues, a coupled force–position control (CFPC) method is presented in this paper by combining the proposed adaptive impedance control method with a modified HFPC method. The selection matrix S of HFPC is replaced with a weighted matrix Sw. A weighted matrix regulator is designed to realize smooth switching between position and force control by adjusting the matrix weights in real time, and an adaptive impedance control algorithm is proposed to improve the force-tracking performance in complex environments. To verify the feasibility of the CFPC method proposed in this paper, simulations and physical experiments were conducted. The results show that the CFPC method has the advantages of a better force-tracking performance and a smoother switching between position and force control compared to the traditional HFPC method. A grinding experiment was conducted to further compare the performances of the HFPC and CFPC methods. The roughness values of the ground plates were 0.059 μm for the HFPC method and 0.031 μm for the proposed CFPC method, which demonstrates that the proposed CFPC method has a better performance. Full article
(This article belongs to the Special Issue Mechanism Design and Control for Robotics)
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10 pages, 4354 KiB  
Article
Novel Magnetic Circuit Design and Acceleration Calculation of Horizontal Linear Vibration Motor
by Zhixiong Jiang, Kihong Park and Sangmoon Hwang
Actuators 2022, 11(6), 149; https://doi.org/10.3390/act11060149 - 2 Jun 2022
Cited by 1 | Viewed by 2098
Abstract
This study proposes a novel magnetic circuit design to reduce the size of horizontal linear vibration motors (HLVMs) used in vehicle touchscreens. The HLVM prototype uses two thick permanent magnets to create a magnetic circuit below the voice coil; however, the novel design [...] Read more.
This study proposes a novel magnetic circuit design to reduce the size of horizontal linear vibration motors (HLVMs) used in vehicle touchscreens. The HLVM prototype uses two thick permanent magnets to create a magnetic circuit below the voice coil; however, the novel design places four thin permanent magnets above and below the voice coil. Moreover, the coil position has been changed to a yoke center to create an effective magnetic circuit with short magnets. Compared with the vertical linear vibration motor, the force calculation method of the HLVM is significantly different. In this study, a new force calculation method is used to analyze the electromagnetic–mechanical coupling of the HLVM. As a prototype, the novel design is small in size (−28.85%) but possesses similar acceleration. The experimental results verify the analysis results of the HLVM in the displacement and acceleration on a dummy jig. Full article
(This article belongs to the Section Control Systems)
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20 pages, 6287 KiB  
Article
Experimental and Numerical Study on Incident Shock Wave/Boundary Layer Interaction Control
by Chuanbiao Zhang, Yanhao Luo, Hua Liang, Shanguang Guo and Hesen Yang
Actuators 2022, 11(6), 148; https://doi.org/10.3390/act11060148 - 2 Jun 2022
Cited by 1 | Viewed by 1891
Abstract
This study was designed to explore the control effect of pulsed arc discharge plasma actuation on the incident shock wave/boundary layer interaction (ISWBLI). Research was conducted on an ISWBLI flow field with 10 kHz single-channel pulsed arc discharge plasma actuation and pulsed arc [...] Read more.
This study was designed to explore the control effect of pulsed arc discharge plasma actuation on the incident shock wave/boundary layer interaction (ISWBLI). Research was conducted on an ISWBLI flow field with 10 kHz single-channel pulsed arc discharge plasma actuation and pulsed arc discharge plasma actuation array applied at Mach 2.0 experimentally and numerically. In the investigation, high-speed schlieren flow field visualization technology was adopted, focusing on the change in shock wave intensity caused by plasma actuation. Combined with the detached eddy simulation (DES) method, the numerical simulation focused on the regulating effect of plasma actuation on the separation zone. The key research results showed that, in terms of the spatial flow field, the simulation results were consistent with the experimental results. The single-channel actuation could only just achieve the control effect on the ISWBLI, while array actuation effectively weakened the shock wave intensity. Furthermore, the ISWBLI separation zone in the base flow field was crescent shaped. Its length at the middle of the flat plate was longer than that at the two sides. It was identified that, after applying single-channel actuation, the start of separation slightly moved forward. Similarly, after the application of array actuation, the start point of separation at the middle section in a spanwise direction moved forward by about 19 mm. The length of the separation zone increased by 30 mm but reduced at the two sides. Its influence, spanwise, was also significantly diminished. Full article
(This article belongs to the Special Issue Active Flow Control: Recent Advances in Fundamentals and Applications)
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18 pages, 9014 KiB  
Article
Development of a Novel Dual Servo Magnetic Levitation Stage
by Dahoon Ahn, Ji-Won Jin, Hyeeun Yun and Jaeheon Jeong
Actuators 2022, 11(6), 147; https://doi.org/10.3390/act11060147 - 30 May 2022
Cited by 5 | Viewed by 2914
Abstract
The main objective of this paper is to propose, design, and control a novel dual servo magnetic levitation stage which is precise and vacuum compatible. The dual servo mechanism, comprising a coarse stage and a fine stage, was applied to a magnetic levitation [...] Read more.
The main objective of this paper is to propose, design, and control a novel dual servo magnetic levitation stage which is precise and vacuum compatible. The dual servo mechanism, comprising a coarse stage and a fine stage, was applied to a magnetic levitation stage system for the first time. The dual servo stage achieves high precision and a long stroke at the same time. The fine stage, which comprises voice coil motors, achieves high-precision motion by overcoming the limit of the coarse stage, the form of which is a planar motor. The planar motor was mathematically modeled and analyzed with respect to the main design parameters, after which the fine stage was optimally designed to be driven by high force. Both stages including a common heat exchanger were manufactured, and the heat exchanger cools down the heat given off from the planar motor and voice coil motors. The position measuring system consisted of laser interferometers and capacitive sensors, and the integrated dual servo stage was controlled with a master–slave control scheme. The experimental results showed a precision of 10 nm, thus confirming the suitability of the developed magnetic levitation stage for a high-precision fabrication process such as wafer lithography. Full article
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17 pages, 4377 KiB  
Article
Fusion Localization Algorithm Based on Robust IMM Model Combined with Semi-Definite Programming
by Yan Wang, Yang Cheng and Long Cheng
Actuators 2022, 11(6), 146; https://doi.org/10.3390/act11060146 - 29 May 2022
Cited by 2 | Viewed by 1608
Abstract
With the continuous development of wireless sensor network (WSN) technology, WSN has gradually become one of the key technologies of the Internet, and is widely used in indoor target location technology. However, the obstacles will have a great influence on the distance measurement, [...] Read more.
With the continuous development of wireless sensor network (WSN) technology, WSN has gradually become one of the key technologies of the Internet, and is widely used in indoor target location technology. However, the obstacles will have a great influence on the distance measurement, and it will result in a large positioning error. Therefore, how to deal with the non-line-of-sight (NLOS) error becomes an important problem. In this paper, Interacting Multiple Model (IMM) was used to identify NOLS/LOS. The NLOS probability was calculated by Markov transform probability, and the likelihood function was calculated by extended Kalman filter (EKF). The NLOS probability was compared with the LOS probability to judge whether the measurement contained the NLOS error. A robust algorithm combining IMM model with semidefinite programming (IMM-SDP) was proposed. The improved convex programming algorithm was proposed to reduce the NLOS error. Simulation and experimental results showed that the proposed algorithm can effectively reduce the influence of NLOS error and achieve higher positioning accuracy compared with the existing positioning methods. Full article
(This article belongs to the Special Issue Wireless Sensor–Actuator Networks)
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14 pages, 5539 KiB  
Article
Research on Control Strategy of Heavy-Haul Train on Long and Steep Downgrades
by Huazhen Yu, Guoxuan Tai, Zhengnan Lin and Youneng Huang
Actuators 2022, 11(6), 145; https://doi.org/10.3390/act11060145 - 28 May 2022
Viewed by 1827
Abstract
The control of heavy-haul trains has always been the focus of China’s railway transportation development. One key challenge is the coordination of electric braking and air braking control when the electric-air combined braking is applied on long and steep downgrades. This is normally [...] Read more.
The control of heavy-haul trains has always been the focus of China’s railway transportation development. One key challenge is the coordination of electric braking and air braking control when the electric-air combined braking is applied on long and steep downgrades. This is normally reliant on manual driving and thus is not cost-effective. To improve the safety and efficiency of train operation in existing heavy-haul railway lines, a multi-label random forest (ML-RF) based approach for heavy-haul train (HHT) operation is proposed. The control characteristics of electric braking and air braking on long and steep downgrades are analyzed first. A prediction model of control strategy is then established with the combination of line conditions and definition of multi-label learning. To evaluate the performance of the model, the 10-fold cross-validation method is adopted. Furthermore, a model parameter optimization algorithm based on evaluation metrics is designed. The feasibility of the proposed approach is demonstrated by the testing results on the actual train running data of one railway line. Full article
(This article belongs to the Section Actuators for Land Transport)
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16 pages, 1239 KiB  
Article
Simultaneous Identification of Free and Supported Frequency Response Functions of a Rotor in Active Magnetic Bearings
by Michael Kreutz, Johannes Maierhofer, Thomas Thümmel and Daniel J. Rixen
Actuators 2022, 11(6), 144; https://doi.org/10.3390/act11060144 - 28 May 2022
Cited by 1 | Viewed by 1846
Abstract
Frequency response functions (FRFs) of rotor systems can be used as indicator functions for condition monitoring. Component-wise FRFs are of high interest to locate errors in the case of defects. To enable continuous monitoring, measurements should be taken during operation. This contribution shows [...] Read more.
Frequency response functions (FRFs) of rotor systems can be used as indicator functions for condition monitoring. Component-wise FRFs are of high interest to locate errors in the case of defects. To enable continuous monitoring, measurements should be taken during operation. This contribution shows methods of using active magnetic bearings (AMBs) for simultaneously determining different FRFs of a rotor system. The AMBs, in addition to supporting the rotor, are used simultaneously as sensors and actuators. Two different types of FRFs, namely, the one associated with the free rotor and with the supported rotor can be determined from a single experiment. This procedure does not need any change in the assembly because the AMBs are simultaneously used as bearing and excitation device. Considering as excitation the total bearing force of the AMBs results in the FRF of the free rotor. The FRF of the supported system is determined by considering a perturbation force only, which is applied on top of the controlled AMB force. As a showcase, an academic rotor test rig is used with and without rotation to verify the applicability of the method. To evaluate and interpret the results of the experiments, a numerical model of the rotor using finite-element formulations is used. Full article
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15 pages, 2639 KiB  
Article
Research on Takagi-Sugeno Fuzzy-Model-Based Vehicle Stability Control for Autonomous Vehicles
by Zeyu Jiao, Jian Wu, Zhengfeng Chen, Fengbo Wang, Lijun Li, Qingfeng Kong and Fen Lin
Actuators 2022, 11(6), 143; https://doi.org/10.3390/act11060143 - 26 May 2022
Cited by 2 | Viewed by 2021
Abstract
Human–machine cooperative driving is an important stage in the development of autonomous driving technology. However, in emergencies, the problem of vehicle stability control for human–computer cooperative autonomous vehicles is still worthy of attention. This paper mainly realizes the stability control of the human–machine [...] Read more.
Human–machine cooperative driving is an important stage in the development of autonomous driving technology. However, in emergencies, the problem of vehicle stability control for human–computer cooperative autonomous vehicles is still worthy of attention. This paper mainly realizes the stability control of the human–machine cooperative driving vehicle through active steering and considers the influence of the change of vehicle speed on the vehicle stability control performance. Therefore, a vehicle stability control method based on the superposition of steering torque is proposed, in which the Takagi-Sugeno fuzzy model is used to solve the variable parameter problem. Firstly, a vehicle system model with steering moment as input is established to ensure that the driver can participate in the steering control. Secondly, the nonlinear T-S fuzzy model is established by fuzzifying the local linear model. Then, the parallel-distributed-compensation (PDC) method is used to design the vehicle stability controller, and the asymptotic stability of the system in the range of variable parameters is proved by using the Lyapunov stability principle. Finally, the simulation and experimental results show that the control method can improve the handling stability of the human–machine cooperative driving vehicle under the condition of vehicle speed variation. Full article
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