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Actuators
Volume 12
Issue 10
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Actuators, Volume 12, Issue 10 (October 2023) – 31 articles

Cover Story (view full-size image): Independent metering is a well-known strategy for making proportional hydraulic cylinder drives more efficient and more flexible because each port of the actuator is controlled individually by independent two-way proportional valves. In this paper, the concept is realized as an open-loop control for a hydraulic cylinder drive, which, in combination with a human operator, constitutes a so-called cybernetic proportional system. The piston velocity commanded by the operator is controlled by the compensation of the static characteristics of the proportional seat-type valves. Basic simulations show the benefits and also the problems of open-loop independent metering. Furthermore, the measurements on one actuator of a real excavator regarding controllability and energy consumption are presented. View this paper
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21 pages, 11705 KiB  
Article
Application of Opposition-Based Learning Jumping Spider Optimization Algorithm in Gas Turbine Coupled Cooling System
by Dazhi Wang, Tianyi Li, Yongliang Ni, Keling Song and Yanming Li
Actuators 2023, 12(10), 396; https://doi.org/10.3390/act12100396 - 23 Oct 2023
Cited by 1 | Viewed by 1560
Abstract
A gas turbine cooling system is a typical multivariable, strongly coupled, nonlinear system; however, the randomness and large disturbances make it difficult to control the variables precisely. In order to solve the problem of precise process control for multi-input and multi-output coupled systems [...] Read more.
A gas turbine cooling system is a typical multivariable, strongly coupled, nonlinear system; however, the randomness and large disturbances make it difficult to control the variables precisely. In order to solve the problem of precise process control for multi-input and multi-output coupled systems with flow, pressure, and temperature, this article conducts the following research: (1) Designing a secondary circuit for waste hot water and establishing a water-circulating gas turbine cooling system to improve the efficiency of waste heat utilization. (2) Identifying the coupled system model and establishing a mathematical model of the coupling relationship based on the characteristic data of input and output signals in the gas turbine cooling system. (3) Designing a coupled-system decoupling compensator to weaken the relationships between variables, realizing the decoupling between coupled variables. (4) An Opposition-based Learning Jumping Spider Optimization Algorithm is proposed to be combined with the PID control algorithm, and the parameters of the PID controller are adjusted to solve the intelligent control problems of heat exchanger water inlet flow rate, pressure, and temperature in the gas turbine cooling system. After simulation verification, the gas turbine cooling system based on an Opposition-based Learning Jumping Spider Optimization Algorithm can realize the constant inlet flow rate, with an error of no more than 1 m3/h, constant inlet water temperature, with an error of no more than 0.2 °C, and constant main-pipe pressure, with an error of no more than 0.01 MPa. Experimental results show that a gas turbine cooling system based on the Opposition-based Learning Jumping Spider Optimization Algorithm can accurately realize the internal variable controls. At the same time, it can provide a reference for decoupling problems in strongly coupled systems, the controller parameter optimization problems, and process control problems in complex systems. Full article
(This article belongs to the Special Issue Applications of Intelligent Control in Actuators Systems)
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18 pages, 7060 KiB  
Article
Torque Increase Strategy for Induction Motor in the Field-Weakening Region Based on Model Predictive Control
by Jingtao Huang, Shuai Liu, Peng Zhang and Yanan Wang
Actuators 2023, 12(10), 395; https://doi.org/10.3390/act12100395 - 22 Oct 2023
Cited by 1 | Viewed by 1861
Abstract
In the field-weakening region, the traditional field-weakening method for induction motor drives based on model predictive control (MPC) is to take a no-load operation as the premise and adjust the flux reference in the cost function proportional to the inverse of the rotor [...] Read more.
In the field-weakening region, the traditional field-weakening method for induction motor drives based on model predictive control (MPC) is to take a no-load operation as the premise and adjust the flux reference in the cost function proportional to the inverse of the rotor speed, which leads to poor torque output. This paper presents a novel field-weakening method for IM drives based on MPC. Considering the induction motor field-weakening limiting conditions and according to the speed adaptive field-weakening strategy with a voltage closed-loop, the speed adaptive field-weakening controllers were designed to optimize the references of the excitation current and torque current. In the rotor field-orientation d–q coordinate system, the stator flux amplitude and torque reference values were optimized by the optimal distribution current. Then, according to the dead-beat control principle, they were converted into an equivalent stator flux vector reference. Moreover, the stator voltage vector reference can be obtained. For an induction motor fed by a three-level neutral point clamped (3L-NPC) inverter, the cost function was constructed by combining all the constraints, including the voltage vector, the neutral potential balance, and the switching frequency. In this way, the high-performance field-weakening operation for the induction motor based on a model predictive control can be realized. The simulation and experiment results show that the proposed method can increase the torque output by 22% in the field-weakening region; at the same time, the steady characteristics and the dynamic response performance can be maintained well. Full article
(This article belongs to the Special Issue Applications of Intelligent Control in Actuators Systems)
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20 pages, 7888 KiB  
Article
Electromechanical Actuator-Based Solution for a Scissor Lift
by Łukasz Stawiński, Viacheslav Zakharov, Andrzej Kosucki and Tatiana Minav
Actuators 2023, 12(10), 394; https://doi.org/10.3390/act12100394 - 21 Oct 2023
Cited by 1 | Viewed by 2907
Abstract
Electrification and hybridization in non-road mobile machinery have attracted considerable attention in recent years. Normally, these green solutions concentrate on drivetrains, slowly penetrating to the implements or, as they are commonly known, working hydraulics. The primary difficulties associated with drivetrains were successfully addressed [...] Read more.
Electrification and hybridization in non-road mobile machinery have attracted considerable attention in recent years. Normally, these green solutions concentrate on drivetrains, slowly penetrating to the implements or, as they are commonly known, working hydraulics. The primary difficulties associated with drivetrains were successfully addressed through the implementation of electric solutions and the utilization of hydraulic configurations. However, existing hydraulics solutions are typically challenged by innovative pure electromechanical solutions to perform the same work. Therefore, the purpose of this study is to illustrate the impact of replacing a conventional hydraulic topology with an electromechanical actuator (EMA) solution. This paper presents a case study of the electrification of a scissor lift, which was evaluated by simulation and experimental works from an energy perspective. The simulation study demonstrated the energy consumption and power requirements in conventional hydraulic (i.e., non-efficient in comparison with advanced systems) and EMA-based topologies for a single lifting cycle. Finally, an average of 35–50% of the consumed energy was saved, which is confirmed based on a completed simulation study case for the scissor lift application. Full article
(This article belongs to the Special Issue Innovative and Intelligent Actuation for Heavy-Duty Applications)
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18 pages, 28485 KiB  
Article
A Soft Actor-Critic Approach for a Blind Walking Hexapod Robot with Obstacle Avoidance
by Lei Wang, Ruiwen Li, Ziwei Huangfu, Yishan Feng and Yiyang Chen
Actuators 2023, 12(10), 393; https://doi.org/10.3390/act12100393 - 21 Oct 2023
Cited by 5 | Viewed by 1893
Abstract
This paper investigates a path planning approach for the walking and obstacle avoidance of a blind hexapod robot in various field conditions. Hexapod robots often perform field tasks in unstructured environments, and their external sensors are affected by weather and light. This paper [...] Read more.
This paper investigates a path planning approach for the walking and obstacle avoidance of a blind hexapod robot in various field conditions. Hexapod robots often perform field tasks in unstructured environments, and their external sensors are affected by weather and light. This paper proposes the use of internal sensors to sense the terrain and a slightly modified soft actor-critic algorithm to train the motion strategy. A hexapod robot is capable of walking smoothly on rough ground only using internal sensors that are not affected by weather factors, and the soft actor-critic approach is superior for overcoming high-dimensional issues for multi-degree-freedom robot motion in unstructured environments.The experiments showed that the hexapod robot not only traversed rugged terrain at a fixed speed but also possessed obstacle avoidance capabilities. Full article
(This article belongs to the Section Actuators for Robotics)
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16 pages, 9168 KiB  
Article
Motion Analysis of Wire Rope Maintenance Device
by Wei Wang, Hao Yang, Yan Chen, Xudong Huang, Jinlong Cao and Weilun Zhang
Actuators 2023, 12(10), 392; https://doi.org/10.3390/act12100392 - 19 Oct 2023
Viewed by 1732
Abstract
This work outlines a design for a wire rope maintenance device that is based on commonly used, low-dropping point lubricating grease for wire rope lubrication and operates along the strand’s twist direction. Unlike similar existing devices, this device scrapes abrasives from the wire [...] Read more.
This work outlines a design for a wire rope maintenance device that is based on commonly used, low-dropping point lubricating grease for wire rope lubrication and operates along the strand’s twist direction. Unlike similar existing devices, this device scrapes abrasives from the wire rope’s surface along the strand’s twist direction and applies lubricating grease in the same direction. It addresses issues related to the accumulation of old lubricating grease between strands, as well as the problems of a heavy weight, high traction force requirements, complex operation, unstable motion, potential surface damage to the wire rope, and the strong pollution found in existing products. The wheel system of this device was kinematically modeled and subjected to force analysis, and its accuracy was verified through simulations and experiments. Test results show that when this device is used for cleaning and lubricating wire ropes, it requires less than 150 N of traction force, maintains a stable speed of 0.6 m/s, and ensures coaxiality within ±0.1 mm, thus meeting the maintenance requirements of ropeway wire ropes. In future work, the effects of different factors, such as changes in scraper shape and size, lubricating grease application speed, and temperature and pressure inside the grease storage chamber can be studied to understand their influence on the application of grease to wire ropes. Full article
(This article belongs to the Section Actuators for Land Transport)
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21 pages, 1712 KiB  
Review
Fault Detection for Point Machines: A Review, Challenges, and Perspectives
by Xiaoxi Hu, Tao Tang, Lei Tan and Heng Zhang
Actuators 2023, 12(10), 391; https://doi.org/10.3390/act12100391 - 18 Oct 2023
Cited by 32 | Viewed by 6600
Abstract
Point machines are the actuators for railway switching and crossing systems that guide trains from one track to another. Hence, the safe and reliable behavior of point machines are pivotal for rail transportation. Recently, scholars and researchers have attempted to deploy various kinds [...] Read more.
Point machines are the actuators for railway switching and crossing systems that guide trains from one track to another. Hence, the safe and reliable behavior of point machines are pivotal for rail transportation. Recently, scholars and researchers have attempted to deploy various kinds of sensors on point machines for anomaly detection and/or incipient fault detection using date-driven algorithms. However, challenges arise when deploying condition monitoring and fault detection to trackside point machines in practical applications. This article begins by reviewing studies on fault and anomaly detection in point machines, encompassing employed methods and evaluation metrics. It subsequently conducts an in-depth analysis of point machines and outlines the envisioned intelligent fault detection system. Finally, it presents eight challenges and promising research directions along with a blueprint for intelligent point machine fault detection. Full article
(This article belongs to the Special Issue Electro-Mechanical Actuator, Diagnostic and Fault-Tolerant Control Systems)
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23 pages, 21774 KiB  
Article
Active Vibration Control Using Loudspeaker-Based Inertial Actuator with Integrated Piezoelectric Sensor
by Minghao Chen, Qibo Mao, Lihua Peng and Qi Li
Actuators 2023, 12(10), 390; https://doi.org/10.3390/act12100390 - 17 Oct 2023
Cited by 2 | Viewed by 2172
Abstract
With the evolution of the aerospace industry, structures have become larger and more complex. These structures exhibit significant characteristics such as extensive flexibility, low natural frequencies, numerous modes, and minimal structural damping. Without implementing vibration control measures, the risk of premature structural fatigue [...] Read more.
With the evolution of the aerospace industry, structures have become larger and more complex. These structures exhibit significant characteristics such as extensive flexibility, low natural frequencies, numerous modes, and minimal structural damping. Without implementing vibration control measures, the risk of premature structural fatigue failure becomes imminent. In present times, the installation of inertial actuators and control signal acquisition units typically requires independent setups, which can be cumbersome for practical engineering purposes. To address this issue, this study introduces a novel approach: an independent control unit combining a loudspeaker-based inertial actuator (LBIA) with an integrated piezoelectric ceramic sensor. This unit enables autonomous vibration control, offering the advantages of ease of use, low cost, and lightweight construction. Experimental verification was performed to assess the mechanical properties of the LBIA. Additionally, a mathematical model for the LBIA with an integrated piezoelectric ceramic sensor was developed, and its efficacy as a control unit for thin plate structure vibration control was experimentally validated, showing close agreement with numerical results. Furthermore, the LBIA’s benefits as an actuator for low-frequency mode control were verified through experiments using external sensors. To further enhance control effectiveness, a mathematical model of the strain differential feedback controller based on multi-bandpass filtering velocity improvement was established and validated through experiments on the clamp–clamp thin plate structure. The experimental results demonstrate that the designed LBIA effectively reduces vibration in low-frequency bands, achieving vibration energy suppression of up to 12.3 dB and 23.6 dB for the first and second modes, respectively. Moreover, the LBIA completely suppresses the vibration of the fourth mode. Additionally, the improved control algorithm, employing bandpass filtering, enhances the effectiveness of the LBIA-integrated sensor, enabling accurate multimodal damping control of the structure’s vibrations for specified modes. Full article
(This article belongs to the Special Issue Dynamics and Control of Aerospace Systems)
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19 pages, 15451 KiB  
Article
Sensor Fault Diagnosis, Isolation, and Accommodation for Heating, Ventilating, and Air Conditioning Systems Based on Soft Sensor
by Lei Nie, Yizhu Ren, Rouhui Wu and Mengying Tan
Actuators 2023, 12(10), 389; https://doi.org/10.3390/act12100389 - 17 Oct 2023
Cited by 5 | Viewed by 1917
Abstract
Heating, Ventilating, and Air Conditioning (HVAC) systems often suffer from unscheduled maintenance or abnormal shutdown due to the fault of their interior sensor system. Traditional fault diagnosis methods for HVAC sensor systems primarily focus on sensor fault diagnosis and isolation, lacking fault accommodation. [...] Read more.
Heating, Ventilating, and Air Conditioning (HVAC) systems often suffer from unscheduled maintenance or abnormal shutdown due to the fault of their interior sensor system. Traditional fault diagnosis methods for HVAC sensor systems primarily focus on sensor fault diagnosis and isolation, lacking fault accommodation. Therefore, to realize effective sensor fault detection, identification, and accommodation (SFDIA), a method for HVAC SFDIA based on the soft sensor is proposed. First, a diagnosis soft sensor with multi-variable input is constructed to estimate the output of the physical sensor being diagnosed. The residual between the estimated value of the diagnosis soft sensor and the measurement of the physical sensor is used as an indicator of the sensor’s condition. If the residual exceeds the fault threshold, the sensor is diagnosed to be faulty. In order to maintain valid sensor output, an accommodation soft sensor is constructed using the historical normal value. The erroneous output of the faulty sensor is substituted by the estimated value from the accommodation soft sensor, thereby realizing sensor fault tolerance control. Experimental results demonstrate that the average false alarm rate for sensor fault diagnosis is 1.57% and the average fault diagnosis rate is 96.51%. The predictive mean absolute error (MAE) and root-mean-square error (RMSE) of the recovered soft sensors are 0.0525 and 0.0738, respectively. Thus, the soft sensors developed in this paper exhibit satisfying ability in HVAC SFDIA. Full article
(This article belongs to the Section Actuators for Manufacturing Systems)
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21 pages, 8541 KiB  
Article
Parameter Optimization of Vibration Reduction Structure for Low-Speed, Multi-Acting Cam Ring Motor
by Gaocheng An, Wenkang Wang, Hongquan Dong, Baoyu Liu, Wei Song and Zhenhua Hu
Actuators 2023, 12(10), 388; https://doi.org/10.3390/act12100388 - 16 Oct 2023
Viewed by 1560
Abstract
To address the issue of serious torque pulsation and optimize the output characteristics of multi-acting cam ring motors at low speed, a sensitivity analysis was conducted on the parameters of the triangular groove at the valve plate. Firstly, a mathematical model of the [...] Read more.
To address the issue of serious torque pulsation and optimize the output characteristics of multi-acting cam ring motors at low speed, a sensitivity analysis was conducted on the parameters of the triangular groove at the valve plate. Firstly, a mathematical model of the flow area between the rotor hole and the valve plate hole was established. Then, a numerical simulation model was built to study the motor output characteristics. Finally, the coupling effect of the triangular groove parameters on the motor torque pulsation rate was analyzed based on the response surface methodology. The results show that the motor torque pulsation rate can be reduced by 55% when adjusting depth angle θ1, width angle θ2, and length l. The influence order of design parameters on the pulsation rate is θ1>l>θ2; among all parameter combinations, the coupling of the triangular groove between the depth angle and the length has the most significant effect on the pulsation rate. Full article
(This article belongs to the Special Issue Recent Advances in the Design Solutions of Electro-Hydraulic Actuators for Mechatronic Systems)
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20 pages, 4589 KiB  
Article
The Design of a Tracking Controller for Flexible Ball Screw Feed System Based on Integral Sliding Mode Control with a Generalized Extended State Observer
by Muzhi Zhu, Dafei Bao and Xingrong Huang
Actuators 2023, 12(10), 387; https://doi.org/10.3390/act12100387 - 15 Oct 2023
Cited by 2 | Viewed by 1674
Abstract
This article proposes a servo control strategy for compensating matched and mismatched perturbations in flexible ball screw feed systems to improve their tracking performance. The perturbations that satisfy or dissatisfy the matching conditions include external disturbances, parameter uncertainties, and unmodeled dynamics. The flexible [...] Read more.
This article proposes a servo control strategy for compensating matched and mismatched perturbations in flexible ball screw feed systems to improve their tracking performance. The perturbations that satisfy or dissatisfy the matching conditions include external disturbances, parameter uncertainties, and unmodeled dynamics. The flexible ball screw feed model includes both a rigid body and first-order axial structural dynamics. A generalized extended state observer is adopted to observe the matched and mismatched perturbations and various state variables of the system, and an improved integral sliding mode controller is proposed that can simultaneously compensate for the perturbations of the system that satisfy and dissatisfy the matching conditions. In addition, vibration compensation is designed for first-order axial vibration of the system to develop a controller that can quickly and accurately track the ideal reference trajectory, suppress system structural vibrations, and be robust to time-varying uncertainties and external disturbances. Finally, the tracking performance, anti-interference performance, and vibration suppression performance of the designed controller are verified via simulation and comparative experiments. Full article
(This article belongs to the Section Control Systems)
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24 pages, 4654 KiB  
Article
Modal Behavior of Microcantilevers Arrays with Tunable Electrostatic Coupling
by Nir Dick and Slava Krylov
Actuators 2023, 12(10), 386; https://doi.org/10.3390/act12100386 - 13 Oct 2023
Viewed by 1405
Abstract
We analyse the spectral content and parametric resonant dynamics of an array of elastically and electrostatically coupled interdigitated micro cantilevers assembled into two identical half-arrays. In this uncommon arrangement, within each of the half-arrays, the beams are coupled only elastically. The half-arrays are [...] Read more.
We analyse the spectral content and parametric resonant dynamics of an array of elastically and electrostatically coupled interdigitated micro cantilevers assembled into two identical half-arrays. In this uncommon arrangement, within each of the half-arrays, the beams are coupled only elastically. The half-arrays are intercoupled only electrostatically, through fringing fields. First, by using the reduced order (RO) model, we analyse the voltage-dependent evolution of the eigenvalues and the eigenvectors of the equivalent mass-spring system, starting from the small two, three and four beams arrays and up to large beams assemblies. We show that at the coupling voltages below a certain critical value, the shape of the eigenvectors, the frequencies of the veering and of the crossing are influenced by the electrostatic coupling and can be tuned by the voltage. Next, by implementing the assumed modes techniques we explore the parametric resonant behavior of the array. We show that in the case of the sub critical electrostatic coupling the actuating voltages required to excite parametric resonance in the damped system can be lower than in a strongly coupled array. The results of the work may inspire new designs of more efficient resonant sensors. Full article
(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Nonlinear Control and Dynamics for MEMS)
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24 pages, 8732 KiB  
Article
Multi-Objective Optimization of Two-Stage Helical Pairs in Helical Hydraulic Rotary Actuator Using Ensemble of Metamodels and NSGA-II
by Song Liu, Baoren Li, Runlin Gan, Yue Xu and Gang Yang
Actuators 2023, 12(10), 385; https://doi.org/10.3390/act12100385 - 13 Oct 2023
Cited by 3 | Viewed by 2084
Abstract
This paper aims to optimize the two-stage helical pairs (TSHPs) in a helical hydraulic rotary actuator (HHRA) in terms of volume, transmission efficiency, and maximum contact stress. Volume and transmission efficiency can be determined through analytical mathematical models. However, calculating the contact stress [...] Read more.
This paper aims to optimize the two-stage helical pairs (TSHPs) in a helical hydraulic rotary actuator (HHRA) in terms of volume, transmission efficiency, and maximum contact stress. Volume and transmission efficiency can be determined through analytical mathematical models. However, calculating the contact stress of helical pairs necessitates complex and time-consuming finite element simulation. To address this issue, a method for predicting the maximum contact stress using an ensemble of metamodels (EMs) is proposed, with an automated finite element simulation process developed for data provision. The superiority of the EMs is validated through comparative analysis with three stand-alone metamodels. The optimization is carried out using the NSGA-II algorithm, including four combinations of the three objectives, and global sensitivity is analyzed over the objectives. The results indicate a trade-off relationship between maximum contact stress and volume in the optimal space. Moreover, considering multiple combinations enhances the robustness of the optimization results. The method is effectively applied to the design of the TSHPs and provides a new idea for the related actuator design. Full article
(This article belongs to the Special Issue Innovative and Intelligent Actuation for Heavy-Duty Applications)
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20 pages, 12262 KiB  
Article
A New Composite Control Strategy for an Astronaut Virtual Operation Training System Based on Cable-Driven Technology
by Feng Xue, Lixun Zhang, Lailu Li, Zhenhan Wang and Da Song
Actuators 2023, 12(10), 384; https://doi.org/10.3390/act12100384 - 12 Oct 2023
Cited by 1 | Viewed by 1448
Abstract
In recent years, virtual microgravity training technology for astronauts based on cable-driven designs has emerged, and it solves the following problems: high costs, short training times, and low safety of existing equipment. However, this technology does not solve the reduced motion accuracy problem [...] Read more.
In recent years, virtual microgravity training technology for astronauts based on cable-driven designs has emerged, and it solves the following problems: high costs, short training times, and low safety of existing equipment. However, this technology does not solve the reduced motion accuracy problem of the operated object due to the elastic deformation of cables, and this problem will reduce the operational experience of astronauts during training. In view of this problem, a cable-driven virtual operation training system for astronauts is designed, and a new composite control strategy based on parallel cables is proposed, which effectively improves motion control accuracy by allocating cable tension and using a tension compliance control method to suppress the influence of cable deformation. In addition, the desired tension of cables is optimized based on the system’s workspace so that the system can achieve more complex virtual microgravity training tasks. Finally, verification via experiments demonstrated that the training system and the new composite control strategy are effective. Full article
(This article belongs to the Section Actuators for Robotics)
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21 pages, 2947 KiB  
Article
Optimal Design Method of Post-Assembly Magnetizing Device with Field–Circuit Coupling Analysis
by Zi-Ang Zhu, Yun-Chong Wang, Xue-Fei Qin, Lei Yao, Johan Gyselinck and Jian-Xin Shen
Actuators 2023, 12(10), 383; https://doi.org/10.3390/act12100383 - 11 Oct 2023
Viewed by 1630
Abstract
Post-assembly magnetization can significantly simplify the manufacturing of the rotor of permanent magnet (PM) electrical machines. The optimization of the post-assembly magnetizing device using finite element analysis (FEA) is time-consuming; therefore, a globally optimal solution aiming at achieving an adequate magnetizing level and [...] Read more.
Post-assembly magnetization can significantly simplify the manufacturing of the rotor of permanent magnet (PM) electrical machines. The optimization of the post-assembly magnetizing device using finite element analysis (FEA) is time-consuming; therefore, a globally optimal solution aiming at achieving an adequate magnetizing level and minimal energy consumption is difficult to achieve. In this paper, a field–circuit coupling analysis (FCCA) model is proposed to optimize the auxiliary stator-type magnetizing device for interior permanent magnet synchronous machines (IPMSMs). A reasonable simplification of the highly saturated magnetic circuit is made based on FEA results so that the magnetic equivalent circuit (MEC) model can be established. On the other hand, the eddy currents in the PMs are equivalent to an eddy current short-circuit; thus, by converting the field calculation into a circuit calculation, the time cost can be reduced significantly, which greatly improves the speed of multi-objective optimization of the magnetizing device with multiple degrees of freedom. A V-type IPMSM is taken as a study case, and its post-assembly magnetizing device is optimized with the proposed method. FEA and experimental results show that the PMs are fully magnetized, while the required energy consumption is greatly reduced when compared with an existing magnetizing device. Full article
(This article belongs to the Special Issue Electromagnetic Actuators)
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22 pages, 1433 KiB  
Article
Investigation and Optimization of Energy Consumption for Hybrid Hydraulic Excavator with an Innovative Powertrain
by Van Hien Nguyen, Tri Cuong Do and Kyoung Kwan Ahn
Actuators 2023, 12(10), 382; https://doi.org/10.3390/act12100382 - 10 Oct 2023
Cited by 3 | Viewed by 1984
Abstract
This paper presents an innovative powertrain design and an energy regeneration system for hybrid hydraulic excavators to reduce energy consumption and emissions. The proposed system is designed to maximize engine efficiency and make full use of the energy gained from boom and arm [...] Read more.
This paper presents an innovative powertrain design and an energy regeneration system for hybrid hydraulic excavators to reduce energy consumption and emissions. The proposed system is designed to maximize engine efficiency and make full use of the energy gained from boom and arm retraction. The powertrain features an innovative design that incorporates a continuously variable transmission (CVT), which drives the main pump. It enables precise control of both the engine’s speed and torque, ensuring that the engine operates within the high-efficiency range. The energy regeneration system is applied to regenerate the potential energy of the boom and arm, which can be used to either charge the battery or directly supply power to the main pump. Moreover, an energy management strategy based on an equivalent consumption minimization strategy is used to distribute the power while offering maximum engine efficiency. When compared with the existing hybrid system and conventional system, the simulation results indicated that the proposed approach achieves energy-saving efficiencies of 16.9% and 77.1%, respectively, at high velocities and 22.25% and 53.5%, respectively, at medium velocities. This research signifies a promising advancement for sustainable and efficient hydraulic excavator operations. Full article
(This article belongs to the Special Issue Innovative and Intelligent Actuation for Heavy-Duty Applications)
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18 pages, 5180 KiB  
Article
Synthesis of a Bistable Recuperative Pump Powered by Shape Memory Alloys and a Two-Section Involute Cam
by Mihail Kostov, Todor Todorov, Rosen Mitrev, Georgi Todorov and Konstantin Kamberov
Actuators 2023, 12(10), 381; https://doi.org/10.3390/act12100381 - 9 Oct 2023
Cited by 1 | Viewed by 1628
Abstract
The paper discusses the synthesis problem of a bistable piston pump, employing a driving mechanism that comprises shape memory alloy wires, a two-section involute cam, and an energy-recuperating spring. The transition from one stable end position to another in the pump is achieved [...] Read more.
The paper discusses the synthesis problem of a bistable piston pump, employing a driving mechanism that comprises shape memory alloy wires, a two-section involute cam, and an energy-recuperating spring. The transition from one stable end position to another in the pump is achieved by heating and subsequently shortening one of the shape memory alloy wires, initiating the motion of the mechanism. This is then followed by the engagement of the recuperative spring to traverse the intermediate unstable equilibrium position and complete the entire stroke. The reversal of motion follows a similar approach, where the second SMA wire shortens while the first wire remains in a cold state. Importantly, the mechanism necessitates a low force within the shape memory alloy wire to initiate motion towards the opposite stable position. This research encompasses the examination of type, geometric, and force synthesis considerations for the pump, leading to the development of fundamental kinematic and force relationships. Moreover, a novel mechanism is proposed and synthesized, incorporating a two-section involute cam with a cusp point, to generate the desired discontinuous moment function produced by the recuperative spring. Further analysis reveals that the thermal time constant, which regulates the dynamic response of the mechanism, is directly proportional to the diameter of the driving SMA and inversely proportional to the square root of the number of SMA branches. Full article
(This article belongs to the Section Actuator Materials)
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19 pages, 7821 KiB  
Article
Electrohydraulic and Electromechanical Buoyancy Change Device Unified Vertical Motion Model
by João Falcão Carneiro, João Bravo Pinto, Fernando Gomes de Almeida and Nuno A. Cruz
Actuators 2023, 12(10), 380; https://doi.org/10.3390/act12100380 - 8 Oct 2023
Cited by 2 | Viewed by 1521
Abstract
Depth control is crucial for underwater vehicles, not only to perform certain tasks that require the vehicle to be still at a given depth but also because most propeller-driven vehicles waste a considerable amount of energy to counteract the passively tuned positive buoyancy. [...] Read more.
Depth control is crucial for underwater vehicles, not only to perform certain tasks that require the vehicle to be still at a given depth but also because most propeller-driven vehicles waste a considerable amount of energy to counteract the passively tuned positive buoyancy. The use of a variable buoyancy system (VBS) can effectively address these items, increasing the energetic efficiency and thus mission length. Achieving accurate depth controllers is, however, a complex task, since experimental controller development in sea or even in test pools is unpractical and the use of simulation requires accurate vertical motion models whose parameters might be difficult to obtain or measure. The development of simple, yet comprehensive, dynamic models for devices incorporating VBS is therefore of upmost importance, as well as developing procedures that allow a simple determination of their parameters. This work contributes to this field by deriving a unified model for the vertical motion of a VBS actuated device, irrespective of the specific technological actuation solution employed, whether it be electromechanical or electrohydraulic. A concise analysis of the open-loop stability of the unified model is presented and a straightforward yet efficient procedure for identifying several of its parameters is introduced. This identification procedure is designed to be convenient and can be carried out in shallow waters, such as test pools, while its results are applicable to the deeper water model as well. To validate the procedure, experimental values obtained from an electromechanical VBS actuated device are used. Closed-loop control of the electromechanical VBS actuated device is conducted through simulation and experimental tests. The results confirm the effectiveness of the proposed unified model and the parameter identification methodology. Full article
(This article belongs to the Section Control Systems)
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17 pages, 7451 KiB  
Article
Rod-Shaped Linear Inertial Type Piezoelectric Actuator
by Andrius Čeponis, Vytautas Jūrėnas, Dalius Mažeika, Vytautas Bakanauskas and Dovilė Deltuvienė
Actuators 2023, 12(10), 379; https://doi.org/10.3390/act12100379 - 7 Oct 2023
Cited by 1 | Viewed by 1723
Abstract
This article presents a numerical and experimental investigation of a novel rod-shaped linear piezoelectric actuator that consists of a square cross-section-shaped rod with eight piezo ceramic plates and a cylindrical guidance rail. The rod has a hollow cut made with an offset from [...] Read more.
This article presents a numerical and experimental investigation of a novel rod-shaped linear piezoelectric actuator that consists of a square cross-section-shaped rod with eight piezo ceramic plates and a cylindrical guidance rail. The rod has a hollow cut made with an offset from the longitudinal axis of the symmetry. A cylindrical guidance rail is placed on one side of the rod, while T-shaped clamping is formed on the opposite side. The slider is mounted on the rail and is moved along it. The actuator is compact, making it possible to mount it directly on a printed circuit board (PCB) or in another device with limited mounting space, restricted mass, or actuator footprint. The operation of the actuator is based on the excitation of the first longitudinal vibration mode of the rod that induces in-plane bending vibration of the nodal zone of the rod due to a hollowed cut asymmetrically placed in the central part of the actuator. The actuator is driven by two sawtooth waveform electric signals with the phase difference of π that allows exciting longitudinal deformations of the rod and controls the reverse motion of the slider. The results of numerical investigations confirmed the operation principle of the actuator at the frequency of 59.72 kHz. The maximum displacement amplitude of the guidance rail in the longitudinal direction reaches up to 152.9 μm while the voltage of 200 Vp-p was applied. An experimental investigation of the actuator was made, and a maximum linear speed of 45.6 mm/s and thrust force of 115.4 mN was achieved. Full article
(This article belongs to the Section Actuator Materials)
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13 pages, 1205 KiB  
Article
Exploring the Just Noticeable Interaction Stiffness Differences of an Impedance-Controlled Series Elastic Actuator
by Rodrigo J. Velasco-Guillen, Felix Schofer, Adna Bliek and Philipp Beckerle
Actuators 2023, 12(10), 378; https://doi.org/10.3390/act12100378 - 5 Oct 2023
Cited by 3 | Viewed by 1510
Abstract
The integration of a passive elastic element in series between a motor and its load is popular in many human–robot interaction scenarios. By virtually imposing elastic behavior on the motor, an impedance control can act as a second stiffness to such an actuator. [...] Read more.
The integration of a passive elastic element in series between a motor and its load is popular in many human–robot interaction scenarios. By virtually imposing elastic behavior on the motor, an impedance control can act as a second stiffness to such an actuator. In this study, we investigated how participants perceived the different stiffness settings in a series elastic actuator by measuring the Just Noticeable Difference (JND) of the real stiffness of the elastic element and the virtual stiffness introduced by impedance control. We conducted a user study during which participants interacted with an impedance-controlled Series Elastic Actuator through a lever. During the user study, we varied the real stiffness of the elastic element and the virtual stiffness. We found that participants seem to perceive both the virtual stiffness and the real stiffness in the same way and in accordance to Weber’s law, which states that the stiffness JND is always equal to a fraction of the initial stiffness. Following these findings, we concluded that the impedance controller can implement an effective virtual stiffness with a behavior comparable to a real torsional spring. Therefore, a system combining real and virtual stiffness can simulate a single combined stiffness for a user interacting with it. Full article
(This article belongs to the Special Issue Actuation Solutions for Wearable Robots)
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15 pages, 4963 KiB  
Article
Octopus-Inspired Robotic Arm Powered by Shape Memory Alloys (SMA)
by Shubham Deshpande and Yara Almubarak
Actuators 2023, 12(10), 377; https://doi.org/10.3390/act12100377 - 4 Oct 2023
Cited by 2 | Viewed by 2561
Abstract
Traditional rigid grippers that are used for underwater systems lack flexibility and have lower degrees of freedom. These systems might damage the underwater environment while conducting data acquisition and data sampling. Soft robotics, which is mainly focused on creating robots with extremely soft [...] Read more.
Traditional rigid grippers that are used for underwater systems lack flexibility and have lower degrees of freedom. These systems might damage the underwater environment while conducting data acquisition and data sampling. Soft robotics, which is mainly focused on creating robots with extremely soft materials are more delicate for the grasping of objects underwater. These systems tend to damage the underwater ecosystem in the least possible way. In this paper, we have presented a simplified design of a soft arm inspired by the octopus arm actuated by coiled Shape Memory Alloys (SMAs) using completely flexible lightweight material. The characterization arm performance under various load and input current conditions is shown. We hope this work will serve as a basis for the future of underwater grasping utilizing soft robotics. Full article
(This article belongs to the Special Issue Soft Actuators and Robotics)
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27 pages, 7450 KiB  
Article
A Modeling and Control Algorithm for a Commercial Vehicle Electronic Brake System Based on Vertical Load Estimation
by Hongyu Zheng, Yafei Xin, Yutai He, Tong Jiang, Xiangzheng Liu and Liqiang Jin
Actuators 2023, 12(10), 376; https://doi.org/10.3390/act12100376 - 30 Sep 2023
Viewed by 1775
Abstract
In the electronic brake system (EBS) of commercial vehicles, due to the compressibility of gas, it is difficult to achieve accurate control in the pneumatic pipeline. To address this issue, a vertical load estimator based on unscented particle filtering (UPF) was designed, which [...] Read more.
In the electronic brake system (EBS) of commercial vehicles, due to the compressibility of gas, it is difficult to achieve accurate control in the pneumatic pipeline. To address this issue, a vertical load estimator based on unscented particle filtering (UPF) was designed, which can estimate vertical load during the running of the vehicle. Then, the EBS dynamics model was established based on software, including a brake signal sensor, single-channel bridge control module, ABS solenoid valve, and dual-channel bridge control module. Finally, based on the characteristics of the EBS valve, the control algorithm of the valve was studied, and the algorithm was tested using a hardware-in-the-loop experiment. The experiment results showed that the designed algorithm could improve braking performance. Full article
(This article belongs to the Section Actuators for Land Transport)
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15 pages, 15125 KiB  
Article
Experimental Validation of a Permanent Magnets Magnetorheological Device under a Standardized Worldwide Harmonized Light-Duty Test Cycle
by Claudia Simonelli, Luca Sani, Nicolò Gori, Miguel Fernández-Muñoz, Antonino Musolino and Rocco Rizzo
Actuators 2023, 12(10), 375; https://doi.org/10.3390/act12100375 - 29 Sep 2023
Cited by 2 | Viewed by 1562
Abstract
In this paper, the experimental validation of an innovative clutch based on magnetorheological fluids (MRFs) excited by permanent magnets is described. The device, used in automotive applications to engage and disengage the vacuum pump, is tested using a standardized Worldwide harmonized Light-duty Test [...] Read more.
In this paper, the experimental validation of an innovative clutch based on magnetorheological fluids (MRFs) excited by permanent magnets is described. The device, used in automotive applications to engage and disengage the vacuum pump, is tested using a standardized Worldwide harmonized Light-duty Test Cycle (WLTC). A test bench is built, and the system is observed in its operation for one hour, considering two consecutive WLTCs. The temperature increase slightly impacts the clutch’s behavior; in particular, the on-state performance of the device, mainly determined by the magnetic field-induced torque, remains largely unaffected by the temperature increase. The results showed that the performance of the proposed MRF-based device is only marginally affected by the phenomena that take place during the actual operation (e.g., temperature increase, shaft slip), confirming the effectiveness of the design. Full article
(This article belongs to the Special Issue Electromagnetic Actuators)
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18 pages, 6980 KiB  
Article
On the Structural Behavior of MEMS Shallow Arch under Combined Effects of In-Plane Parallel Fields and Out-of-Plane Fringing-Fields
by Hassen M. Ouakad, Fehmi Najar and Najib Kacem
Actuators 2023, 12(10), 374; https://doi.org/10.3390/act12100374 - 28 Sep 2023
Viewed by 1443
Abstract
We propose to study the nonlinear stroke and lower-order modal interactions of a clamped–clamped shallow-arch flexible micro-electrode. The flexible electrode is electrically actuated through an in-plane parallel-plates field superimposed over out-of-plane electrostatic fringing fields. The in-plane electrostatic fields result from a difference of [...] Read more.
We propose to study the nonlinear stroke and lower-order modal interactions of a clamped–clamped shallow-arch flexible micro-electrode. The flexible electrode is electrically actuated through an in-plane parallel-plates field superimposed over out-of-plane electrostatic fringing fields. The in-plane electrostatic fields result from a difference of potential between the initially curved flexible electrode and a lower stationary parallel-grounded electrode. Moreover, the out-of-plane fringing fields are mainly due to the out-of-plane asymmetry of the flexible shallow arch and two respective surrounding stationary side electrodes (left and right). A nonlinear beam model is first introduced, consisting of a nonlinear partial differential equation governing the flexible shallow-arch in-plane deflection. Then, a resultant reduced-order model (ROM) is derived assuming a Galerkin modal decomposition with mode-shapes of a clamped–clamped beam as basis functions. The ROM coupled modal equations are numerically solved to obtain the static deflection. The results indicate the possibility of mono-stable and bi-stable structural behaviors for this particular device, depending on the flexible electrode’s initial rise and the size of its stationary side electrodes. The eigenvalue problem is also derived and examined to estimate the variation of the first three lower natural frequencies of the device when the microbeam is electrostatically actuated. The proposed micro-device is tunable with the possibility of pull-in-free states in addition to modal interactions through linear coupled mode veering and crossover processes. Remarkably, the veering zone between the first and third modes can be electrostatically adjusted and reach 22.6kHz for a particular set of design parameters. Full article
(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Nonlinear Control and Dynamics for MEMS)
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21 pages, 10573 KiB  
Article
Adaptive Super-Twisting Sliding Mode Control of Underwater Mechanical Leg with Extended State Observer
by Lihui Liao, Luping Gao, Mboulé Ngwa, Dijia Zhang, Jingmin Du and Baoren Li
Actuators 2023, 12(10), 373; https://doi.org/10.3390/act12100373 - 27 Sep 2023
Cited by 4 | Viewed by 1569
Abstract
Underwater manipulation is one of the most significant functions of the deep-sea crawling and swimming robot (DCSR), which relies on the high-accuracy control of the body posture. As the actuator of body posture control, the position control performance of the underwater mechanical leg [...] Read more.
Underwater manipulation is one of the most significant functions of the deep-sea crawling and swimming robot (DCSR), which relies on the high-accuracy control of the body posture. As the actuator of body posture control, the position control performance of the underwater mechanical leg (UWML) thus determines the performance of the underwater manipulation. An adaptive super-twisting sliding mode control method based on the extended state observer (ASTSMC-ESO) is proposed to enhance the position control performance of the UWML by taking into account the system’s inherent nonlinear dynamics, uncertainties, and the external disturbances from hydrodynamics, dynamic seal resistance, and compensation oil viscous resistance. This newly designed controller incorporates sliding mode (SMC) feedback control with feedforward compensation of the system uncertainties estimated by the ESO, and the external disturbances of the hydrodynamics by fitting the parameters, the dynamic seal resistance, and the compensation oil viscous resistance to the tested results. Additionally, an adaptive super-twisting algorithm (AST) with integral action is introduced to eliminate the SMC’s chattering phenomenon and reduce the system’s steady-state error. The stability of the proposed controller is proved via the Lyapunov method, and the effectiveness is verified via simulation and comparative experimental studies with SMC and the adaptive fuzzy sliding mode control method (AFSMC). Full article
(This article belongs to the Special Issue Advanced Robots: Design, Control and Application—2nd Edition)
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20 pages, 1485 KiB  
Article
Uncertainty-Estimation-Based Prescribed Performance Pressure Control for Train Electropneumatic Brake Systems
by Rui Zhang, Zejun Xu, Yingze Yang and Peidong Zhu
Actuators 2023, 12(10), 372; https://doi.org/10.3390/act12100372 - 27 Sep 2023
Cited by 2 | Viewed by 1529
Abstract
Fast and precise pressure control for an electropneumatic brake system is essential for ensuring the safe operation of trains. However, the nonlinearity and uncertainties of the system make controller design challenging. This paper proposes a prescribed performance control method integrating an extended state [...] Read more.
Fast and precise pressure control for an electropneumatic brake system is essential for ensuring the safe operation of trains. However, the nonlinearity and uncertainties of the system make controller design challenging. This paper proposes a prescribed performance control method integrating an extended state observer to address this issue. A thermodynamical model of the brake cylinder is first built based on the pneumatic characteristics of the braking system, considering multiple modes, coupling effects, and input saturation. Then, an extended state observer is designed to estimate model uncertainty due to temperature variation and disturbances and to achieve online compensation of the model. A feedback control law with a specified prescribed performance function is developed based on the updated thermodynamic model to guarantee the transient and steady-state performance of the pressure control. A parameter adaptive method is also utilized to handle input saturation. The observer’s bounded convergence and stability analysis of the closed-loop control system is given using the Lyapunov theory. Compared experimental results are provided to verify the effectiveness of the proposed method. Full article
(This article belongs to the Section Actuators for Land Transport)
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17 pages, 4101 KiB  
Article
Vehicle Sideslip Angle Estimation Based on Radial Basis Neural Network and Unscented Kalman Filter Algorithm
by Chuanwei Zhang, Yansong Feng, Jianlong Wang, Peng Gao and Peilin Qin
Actuators 2023, 12(10), 371; https://doi.org/10.3390/act12100371 - 26 Sep 2023
Cited by 4 | Viewed by 1744
Abstract
Most existing ESC (electronic stability control) and ADS (auto drive system) stability controls rely on the measurement of yaw rate and sideslip angle. However, the existing sensors are too expensive, which is one of the factors that makes it difficult to measure the [...] Read more.
Most existing ESC (electronic stability control) and ADS (auto drive system) stability controls rely on the measurement of yaw rate and sideslip angle. However, the existing sensors are too expensive, which is one of the factors that makes it difficult to measure the side slip angle of vehicles directly. Therefore, the estimation of sideslip angle has been extensively discussed in the relevant literature. Accurate modeling is complicated by the fact that vehicles are highly nonlinear. This article combines a radial basis function neural network with an unscented Kalman filter to propose a new sideslip angle estimation method for controlling the dynamic behavior of vehicles. Considering the influence of input data type and sensor ease of measurement factors on the results, a two-degrees-of-freedom vehicle nonlinear dynamic model was established, and a radial basis function neural network estimation algorithm was designed. In order to reduce the impact of noise and improve the reliability of the algorithm, the neural network algorithm was combined with the Kalman filter. The information collected from low-cost sensors for actual vehicle operation (longitudinal vehicle speed, steering wheel angle, yaw rate, lateral acceleration) was trained using a radial basis function neural network to obtain a “pseudo slip angle”. The “pseudo slip angle”, yaw rate, and lateral acceleration are input as observations of the Kalman filter. The sideslip angle obtained from different observation methods was compared with the values provided by the Carsim 2020. The experiment shows that the sideslip angle estimator based on the radial basis function neural network and unscented Kalman filter achieves the optimal effect. Full article
(This article belongs to the Special Issue Integrated Intelligent Vehicle Dynamics and Control)
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17 pages, 4129 KiB  
Article
Cybernetic Proportional System for a Hydraulic Cylinder Drive Using Proportional Seat-Type Valves
by Helmut Kogler, Andreas Plöckinger and Paul Foschum
Actuators 2023, 12(10), 370; https://doi.org/10.3390/act12100370 - 26 Sep 2023
Cited by 1 | Viewed by 1941
Abstract
Hydraulic cylinders are well known as cheap and robust actuators for moving heavy loads, especially in harsh environments. For this reason, they are often used in construction machines such as excavators. Basically, the hydraulic cylinders are controlled by four-way proportional spool valves, resulting [...] Read more.
Hydraulic cylinders are well known as cheap and robust actuators for moving heavy loads, especially in harsh environments. For this reason, they are often used in construction machines such as excavators. Basically, the hydraulic cylinders are controlled by four-way proportional spool valves, resulting in poor energy efficiency due to resistance control. Furthermore, because all valve edges are located at the same spool, common proportional valves suffer from limited flexibility with regard to different loads. Independent metering (IM) is a well-known strategy for making proportional hydraulic drives more efficient and more flexible because each port of the actuator can be connected individually to pressure or tank by independent two-way proportional valves. In this paper, the IM concept is realized as an open-loop control for a hydraulic cylinder drive, which, in combination with a human operator, constitutes a so-called cybernetic proportional system (CPS). The piston velocity commanded by the operator is controlled by the compensation of the static characteristics of the proportional seat-type valves. Basic simulations show the benefits and also the problems of open-loop independent metering. Furthermore, measurements on one actuator of a real excavator regarding controllability and energy consumption are presented. Full article
(This article belongs to the Section Control Systems)
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16 pages, 8073 KiB  
Article
Selection of Design Scheme for an Ultrahigh-Pressure Hydrostatic Extrusion Cylinder
by Jian Yang, Lei Zhang, Jun Zhang, Hao Wang, Dong Zhang, Yuanxin Luo and Yongqin Wang
Actuators 2023, 12(10), 369; https://doi.org/10.3390/act12100369 - 25 Sep 2023
Viewed by 1338
Abstract
In this study, the mechanical models of a multilayer combined extrusion cylinder and a steel-wire-winding extrusion cylinder were established and compared using a finite element simulation and existing experimental cases. This work provides theoretical support for the selection of an ultrahigh-pressure extrusion cylinder. [...] Read more.
In this study, the mechanical models of a multilayer combined extrusion cylinder and a steel-wire-winding extrusion cylinder were established and compared using a finite element simulation and existing experimental cases. This work provides theoretical support for the selection of an ultrahigh-pressure extrusion cylinder. Comparative analysis of an ultrahigh-pressure extrusion structure was carried out. The mathematical optimization model is established based on the mechanical model, and the ultimate bearing capacities of the schemes are compared. Additionally, the winding mode and the number of core layers of the extrusion cylinder are compared and analyzed, which provides a theoretical basis for the parameter design of the steel-wire-winding ultrahigh-pressure extrusion cylinder. This work holds good theoretical significance and practical value for the promotion and application of ultrahigh-pressure hydrostatic extrusion technology. Full article
(This article belongs to the Special Issue Innovative and Intelligent Actuation for Heavy-Duty Applications)
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19 pages, 5151 KiB  
Article
Design and Experiment of a Multi-DOF Shaker Based on Rotationally Symmetric Stewart Platforms with an Insensitive Condition Number
by Chao Liang, Weipeng Li, Hai Huang and Yan Zheng
Actuators 2023, 12(10), 368; https://doi.org/10.3390/act12100368 - 25 Sep 2023
Viewed by 1531
Abstract
This study proposes a method for designing a class of rotationally symmetric Stewart platforms (RSSPs) with an insensitive condition number (ICN), which is used to minimize the condition number to achieve a high accuracy for a multi-degree-of-freedom (multi-DOF) shaker. Considering the rotational symmetry [...] Read more.
This study proposes a method for designing a class of rotationally symmetric Stewart platforms (RSSPs) with an insensitive condition number (ICN), which is used to minimize the condition number to achieve a high accuracy for a multi-degree-of-freedom (multi-DOF) shaker. Considering the rotational symmetry of RSSPs, an analytical relationship between the architecture parameters and transfer coefficients is first established. Then, the decoupling conditions of the RSSPs are derived, and the transfer coefficient formulas are simplified by the given decoupling conditions and iso-length assumption. Following further analyses and discussions, the ICN condition and analytical form of the condition number are provided. The area of the ICN (AICN) is, subsequently, derived to evaluate the insensitivity of the condition number. To validate the effectiveness of the method, a design example (ICN-RSSP), along with a numerical analysis, is implemented, and, finally, a multi-DOF shaker is developed. The results of the numerical analysis show a smaller condition number and a larger AICN than those of the RSSP, for comparison. And the experiment results of the multi-DOF shaker show a high accuracy of vibration waveform reproduction. The method can reduce the condition number of RSSPs, improve the insensitivity, and further improve the accuracy of the multi-DOF shaker. Full article
(This article belongs to the Section Actuators for Robotics)
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19 pages, 14212 KiB  
Article
Multi-Objective Optimization Design of Permanent Magnet Eddy Current Coupler Based on SCG-BP Neural Network Modeling and the ONDX-NSGA-II Algorithm
by Dazhi Wang, Bowen Niu, Pengyi Pan and Guofeng Sun
Actuators 2023, 12(10), 367; https://doi.org/10.3390/act12100367 - 25 Sep 2023
Cited by 1 | Viewed by 1470
Abstract
There is a complex coupling relationship between the structural parameters and various performance indicators of a permanent magnet eddy current coupler. In order to obtain the optimal combination of structural parameters that can improve the overall performance of the coupler, it is necessary [...] Read more.
There is a complex coupling relationship between the structural parameters and various performance indicators of a permanent magnet eddy current coupler. In order to obtain the optimal combination of structural parameters that can improve the overall performance of the coupler, it is necessary to reasonably balance the contradiction and competition among performance indicators of the permanent magnet eddy current coupler. A multi-objective optimization method for permanent magnet eddy current couplers based on scaled conjugate gradient back propagation neural network modeling, improved opposition-based learning, and normal distribution crossover operator non-dominated sorting genetic algorithm-II is proposed. The optimization results are compared with those of the traditional non-dominated sorting genetic algorithm-II and the Pareto envelope-based selection algorithm-II, and it is verified that the proposed multi-objective optimization algorithm is accurate, reliable, and has better convergence and versatility. Compared with the original model, the output torque of the optimized coupler increased by 8.54%, and the eddy current loss and cost decreased by 3.71% and 8.74%, respectively. Finally, the correctness of the theoretical analysis was verified through 3D finite element simulation and an experimental simulation platform. Full article
(This article belongs to the Special Issue Electromagnetic Actuators)
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