Journal Description
Actuators
Actuators
is an international, peer-reviewed, open access journal on the science and technology of actuators and control systems published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, and other databases.
- Journal Rank: JCR - Q2 (Engineering, Mechanical) / CiteScore - Q2 (Control and Optimization)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 16.7 days after submission; acceptance to publication is undertaken in 2.5 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.6 (2022);
5-Year Impact Factor:
2.6 (2022)
Latest Articles
Passive and Active Training Control of an Omnidirectional Mobile Exoskeleton Robot for Lower Limb Rehabilitation
Actuators 2024, 13(6), 202; https://doi.org/10.3390/act13060202 (registering DOI) - 25 May 2024
Abstract
As important auxiliary equipment, rehabilitation robots are widely used in rehabilitation treatment and daily life assistance. The rehabilitation robot proposed in this paper is mainly composed of an omnidirectional mobile platform module, a lower limb exoskeleton module, and a support module. According to
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As important auxiliary equipment, rehabilitation robots are widely used in rehabilitation treatment and daily life assistance. The rehabilitation robot proposed in this paper is mainly composed of an omnidirectional mobile platform module, a lower limb exoskeleton module, and a support module. According to the characteristics of the robot’s omnidirectional mobility and good stiffness, the overall kinematic model of the robot is established using the analytical method. Passive and active training control strategies for an omnidirectional mobile lower limb exoskeleton robot are proposed. The passive training mode facilitates the realization of the goal of walking guidance and assistance to the human lower limb. The active training mode can realize the cooperative movement between the robot and the human through the admittance controller and the tension sensor and enhance the active participation of the patient. In the simulation experiment, a set of optimal admittance parameters was obtained, and the parameters were substituted into the controller for the prototype experiment. The experimental results show that the admittance-controlled rehabilitation robot can perceive the patient’s motion intention and realize the two walking training modes. In summary, the passive and active training control strategies based on admittance control proposed in this paper achieve the expected purpose and effectively improve the patient’s active rehabilitation willingness and rehabilitation effect.
Full article
(This article belongs to the Special Issue Intelligent Systems, Robots and Devices for Healthcare and Rehabilitation)
Open AccessArticle
Ramp Start and Speed Control of Self-Driving Commercial Vehicles under Ramp and Vehicle Load Uncertainty
by
Dequan Zeng, Huafu Fang, Yinquan Yu, Yiming Hu, Peizhi Zhang and Wei Luo
Actuators 2024, 13(6), 201; https://doi.org/10.3390/act13060201 - 24 May 2024
Abstract
In order to improve the performance of self-driving commercial vehicles for half-hill starting, a ramp control strategy based on the back-slip speed corresponding to the parking moment is proposed. Firstly, the longitudinal dynamics model of the vehicle is established, the force of the
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In order to improve the performance of self-driving commercial vehicles for half-hill starting, a ramp control strategy based on the back-slip speed corresponding to the parking moment is proposed. Firstly, the longitudinal dynamics model of the vehicle is established, the force of the vehicle on the ramp is analyzed, and the rear slip speed of the vehicle is matched with the parking moment, and finally the target speed is tracked based on the sliding-mode controller, and in order to validate the validity of the method, two comparative algorithms of the pure PI controller and the proportional gain controller based on the back-sliding speed corresponding to the resting moment are designed for comparative experiments, and the data results show that the control strategy based on the resting moment corresponding to the backsliding speed of the sliding mode ramp start control strategy can stably complete the ramp start under different weights and different slopes, and greatly reduce the backsliding distance of the vehicle.
Full article
(This article belongs to the Special Issue Advanced Actuation and Control Technologies for Vehicle Driving Systems)
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Open AccessArticle
High-Performance Nanocellulose-Based Ionic Electroactive Soft Actuators
by
Yujiao Wu, Qiyuan Cui and Fan Wang
Actuators 2024, 13(6), 200; https://doi.org/10.3390/act13060200 - 24 May 2024
Abstract
High-performance electroactive polymer actuators with large bending, fast response, and high durability have gained attention in the development of micromanipulators and multifunctional bionic soft robots. Herein, we developed high-performance electroactive soft actuators fabricated with ultrathin free-standing microfibrillated cellulose (MFC)-reinforced poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS) with multi-walled
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High-performance electroactive polymer actuators with large bending, fast response, and high durability have gained attention in the development of micromanipulators and multifunctional bionic soft robots. Herein, we developed high-performance electroactive soft actuators fabricated with ultrathin free-standing microfibrillated cellulose (MFC)-reinforced poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS) with multi-walled carbon nanotube (MWCNT)-doped composite electrode films and ion-exchange Nafion membranes by a hot-pressing method. The prepared PEDOT/PSS-MFC-MWCNT electrodes have good film-forming properties with a Young’s modulus of 448 MPa and an electrical conductivity of 75 S/cm. The proposed PEDOT/PSS-MFC-MWCNT/Nafion soft actuators have a sustained peak displacement of 2.1 mm and a long-term cyclic stability of 94% with no degradation over 1 h at 1.0 V, 0.1 Hz. Furthermore, we fabricated soft micro-grippers based on the actuators for mimicking actual finger actions for grasping, pointing, and counting, which introduces new possibilities for the next-generation development of micromanipulators and bionic soft robotics.
Full article
(This article belongs to the Special Issue Soft Robotics: Actuation, Control, and Application)
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Open AccessArticle
Magnetically Actuated Transport Pipeline with Self-Perception
by
Quan Shu, Shaolin Ge, Yanfang Li and Shouhu Xuan
Actuators 2024, 13(6), 199; https://doi.org/10.3390/act13060199 - 22 May 2024
Abstract
Soft transportation devices with high flexibility, good stability, and quick controllability have attracted increasing attention. However, a smart soft transportation device with tactile perception and a non-contact actuating mode remains a challenge. This work reports a magnetic soft pipeline (MSP) composed of sensor
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Soft transportation devices with high flexibility, good stability, and quick controllability have attracted increasing attention. However, a smart soft transportation device with tactile perception and a non-contact actuating mode remains a challenge. This work reports a magnetic soft pipeline (MSP) composed of sensor film, a magnetorheological elastomer (MRE) cavity pipeline, and heater film, which can not only respond well to tactile compression stimuli but also be transported by magnetic actuation. Notably, the sensor film was integrated on the upper surface of an MRE pipeline, and the relative resistance change (∆R/R0) of the MSP was maintained at 55.8% under 2.2 mm compression displacement during 4000 loading cycles. Moreover, the heater film was integrated on the lower surface of the MRE pipeline, which endows the MSP with an electrothermal heating characteristic. The temperature of the MSP can be increased from 26.7 °C to 38.1 °C within 1 min under 0.6 V. Furthermore, the MSP was attracted and deformed under the magnetic field, and the ∆R/R0 of the MSP reached 69.1% under application of a 165 mT magnetic field density. Benefiting from the excellent perception and magnetic deformation performances, the magnetic actuate transportation of the MSP with self-sensing was successfully achieved. This multi-functional soft pipeline integrated with in situ self-sensing, electrothermal heating, and non-contact magnetic actuating transportation performance possess high potential in smart flexible electronic devices.
Full article
(This article belongs to the Special Issue Advances in Smart Materials-Based Actuators)
Open AccessArticle
Analysis of Parameter Matching on the Steady-State Characteristics of Permanent Magnet-Assisted Synchronous Reluctance Motors under Vector Control
by
Yu-Hua Lan, Wen-Jie Wan and Jin Wang
Actuators 2024, 13(6), 198; https://doi.org/10.3390/act13060198 - 22 May 2024
Abstract
In this paper, the impact of parameter matching on the steady-state performance of permanent magnet-assisted synchronous reluctance motors (PMaSynRM) under vector control is analyzed and discussed. First, based on the mathematical model of motors under the maximum torque per ampere (MTPA) control strategy,
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In this paper, the impact of parameter matching on the steady-state performance of permanent magnet-assisted synchronous reluctance motors (PMaSynRM) under vector control is analyzed and discussed. First, based on the mathematical model of motors under the maximum torque per ampere (MTPA) control strategy, an analysis is conducted concerning two main parameters, i.e., the matching relationship between the back electromotive force (back-EMF) and the saliency ratio. The impact of these two parameters on the operational status of the motor is investigated. Then, the motor’s voltage operating conditions are examined, and the operating curve under minimum voltage is derived. Furthermore, in the overvoltage region under the MTPA control strategy, the operation of the motor under the maximum torque per voltage (MTPV) control strategy is explored. This analysis illuminated the patterns of influence exerted by the back-EMF and the saliency ratio on the motor’s voltage operating condition. Between these two control strategies, there remains scope for the motor to operate at its limits. An enhanced understanding of the effects of the back-EMF and saliency ratio within this range on motor performance was achieved, resulting in the optimal matching curve for the back-EMF and saliency ratio. Finally, a 45 kW PMaSynRM was designed, prototyped, and tested to validate the correctness of the design techniques, with the motor achieving IE5 efficiency.
Full article
(This article belongs to the Special Issue Power Electronics and Actuators)
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Open AccessArticle
The Design and Analysis of a Tunnel Retro-Reflective Ring Climbing and Cleaning Robot
by
Yuhan Li, Shiqing Ye, Rongxu Cui and Zhaoyu Shou
Actuators 2024, 13(6), 197; https://doi.org/10.3390/act13060197 - 22 May 2024
Abstract
In response to the challenges posed by the difficult cleaning of tunnel retro-reflective rings and the unsuitability of existing climbing robots for ascending tunnel retro-reflective rings, a tunnel retro-reflective ring cleaning robot is proposed. Firstly, based on the analysis of the operational and
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In response to the challenges posed by the difficult cleaning of tunnel retro-reflective rings and the unsuitability of existing climbing robots for ascending tunnel retro-reflective rings, a tunnel retro-reflective ring cleaning robot is proposed. Firstly, based on the analysis of the operational and environmental characteristics and functional requirements inside the tunnel, the design and planning of the robot’s main framework, motion system, cleaning mechanism, and intelligent detection system are conducted to evaluate its walking ability under various working conditions, such as aluminum plate overlaps and rivet protrusions. Subsequently, stability analysis is performed on the robot. The static analysis explored conditions that can make the climbing robot stable, the dynamic analysis obtained the minimum driving torque and finally, verified the stability of the robot through experiments. After that, by changing the material and thickness of the main framework for deformation simulation analysis, the optimal parameters to optimize the design of the main framework are found. Finally, the three factors affecting the cleaning effect of the robot are discussed by the response surface method, and single factor analysis and response surface regression analysis are carried out, respectively. The mathematical regression model of the three factors is established and the best combination of the three factors is found. The cleaning effect is best when the cleaning disc pressure is 5.101 N, the walking wheel motor speed is 36.93 rad/min, and the cleaning disc motor speed is 38.252 rad/min. The development of this machine can provide equipment support for the cleaning of tunnel retro-reflective rings, reducing the requirement of manpower and material resources.
Full article
(This article belongs to the Special Issue Advanced Robots: Design, Control and Application—2nd Edition)
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Open AccessArticle
Axial Stiffness Augmentation by adding Superconductor Bulks or Limiting Permanent Magnet Rings to a Horizontal Axis Zero-Field Cooled High-Tc Radial Passive Superconducting Bearing
by
António J. Arsénio Costa, João F. P. Fernandes and Paulo J. Costa Branco
Actuators 2024, 13(6), 196; https://doi.org/10.3390/act13060196 - 21 May 2024
Abstract
This paper analyzes the viability of different solutions to passively augment the axial stiffness of a horizontal axis radial levitation passive magnetic bearing (PMB) with a previously studied topology. The zero-field cooling (ZFC) of high-temperature superconductor (HTS) bulks promotes higher magnetic impulsion and
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This paper analyzes the viability of different solutions to passively augment the axial stiffness of a horizontal axis radial levitation passive magnetic bearing (PMB) with a previously studied topology. The zero-field cooling (ZFC) of high-temperature superconductor (HTS) bulks promotes higher magnetic impulsion and levitation forces and lower electromagnetic losses than those with field-cooling (FC) but, on the other hand, the guiding stability is much lower than those with FC. Because of stability reasons, FC was adopted in most superconducting maglev systems. The trend of this research group has been to develop a horizontal axis HTS ZFC radial levitation PMB presenting notable levitation forces with reduced electromagnetic losses, defined by a topology that creates guiding stability. Previous work has shown that optimizing the bearing geometry to maximize magnetic guidance forces might not be enough to guarantee the axial stiffness required for many applications. First, the extent to which guidance forces are augmented by increasing the number of HTS bulks in the stator is evaluated. Then, the axial stiffness augmentation by passively adding two limiting permanent magnet (PM) rings is evaluated. The results show that the axial stiffness is highly augmented by adding limiting PM rings with no significant additional investment. This change enables the use of the studied ZFC superconducting PMB in high-precision axial stability applications, such as precision gyroscopes, horizontal axis propellers, and turbines.
Full article
(This article belongs to the Special Issue Advances in High-Precision Magnetic Levitation Actuators)
Open AccessArticle
Research on Delamination Damage Localization of Carbon Fiber-Reinforced Polymer Curved Plate Using Lamb Wave
by
Quanpeng Yu, Shiyuan Zhou, Yuhan Cheng and Yao Deng
Actuators 2024, 13(6), 195; https://doi.org/10.3390/act13060195 - 21 May 2024
Abstract
Carbon fiber-reinforced polymers (CFRPs) are extensively employed in the aerospace industry due to their excellent properties. Delamination damage occurring at critical locations in CFRPs can seriously reduce the safety of in-service components. The detection and localization of delamination damage using Lamb waves hold
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Carbon fiber-reinforced polymers (CFRPs) are extensively employed in the aerospace industry due to their excellent properties. Delamination damage occurring at critical locations in CFRPs can seriously reduce the safety of in-service components. The detection and localization of delamination damage using Lamb waves hold significant potential for widespread application in non-destructive testing. However, the choice of damage localization algorithm may produce different delamination damage localization results. This research presented an IRAPID (improved reconstruction algorithm for probabilistic inspection of defects) method derived from the RAPID (reconstruction algorithm for probabilistic inspection of defects) method, aiming to improve the accuracy and reliability of delamination damage localization. Three CFRP curved plates, including a healthy curved plate and two curved plates with delamination damage sizes of Φ20 mm and Φ40 mm, were prepared in the experiment. The detection experiment of the CFRP curved plate using lead zirconate titanate (PZT) as a transducer to excite and receive Lamb waves was conducted, and the influence of excitation signal frequency on the performance of the proposed method was discussed. Under the condition of an excitation signal frequency of 220~320 kHz and a step size of 10 kHz, the accuracy of the delamination damage localization method proposed in this paper was compared with that of existing methods. The experimental results indicate that the IRAPID algorithm exhibits good stability in the localization of delamination damage across the range of frequency variations considered. The localization error of the IRAPID algorithm for delamination damage is significantly lower than that of the DaS (delay-and-sum) algorithm and the RAPID algorithm. As the size of the delamination damage increases, so does the localization error. The accuracy of delamination damage localization is lower in the X-axis direction than in the Y-axis direction. By averaging the localization results across various frequencies, we can mitigate the potential localization errors associated with single-frequency detection to a certain extent. For the localization of delamination damage, Lamb waves at multiple frequencies can be employed for detection, and the detection results at each frequency are averaged to enhance the reliability of localization.
Full article
(This article belongs to the Section Actuators for Manufacturing Systems)
Open AccessArticle
Investigation on the Reduced-Order Model for the Hydrofoil of the Blended-Wing-Body Underwater Glider Flow Control with Steady-Stream Suction and Jets Based on the POD Method
by
Huan Wang, Xiaoxu Du and Yuli Hu
Actuators 2024, 13(6), 194; https://doi.org/10.3390/act13060194 - 21 May 2024
Abstract
The rapid acquisition of flow field characterization information is crucial for closed-loop active flow control. The proper orthogonal decomposition (POD) method is a widely used flow field downscaling modeling method to obtain flow characteristics effectively. Based on the POD method, a flow field
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The rapid acquisition of flow field characterization information is crucial for closed-loop active flow control. The proper orthogonal decomposition (POD) method is a widely used flow field downscaling modeling method to obtain flow characteristics effectively. Based on the POD method, a flow field reduced-order model (ROM) is constructed in this paper for the flow field control of a hydrofoil of a blended-wing-body underwater glider (BWB-UG) with stabilized suction and blowing forces. Compared with the computational fluid dynamics (CFD) simulation, the computational time required to predict the target flow field using the established POD-ROM is only about 0.1 s, which is significantly less than the CFD simulation time. The average relative error of the predicted surface pressure is not more than 6.9%. These results confirm the accuracy and efficiency of the POD-ROM in reconstructing flow characteristics. The timeliness problem of fast flow field prediction in BWB-UG active flow control is solved by establishing a fast prediction model in an innovative way.
Full article
(This article belongs to the Special Issue Active Flow Control: Recent Advances in Fundamentals and Applications — Volume II)
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Study on Working Characteristics of 4-Column Hydraulic Support in Lifting–Lowering–Moving State Based on Microcontact Theory and Rigid–Flexible–Mechanical–Hydraulic Coupling Simulation Model
by
Bowen Xie and Yang Yang
Actuators 2024, 13(5), 193; https://doi.org/10.3390/act13050193 - 20 May 2024
Abstract
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A hydraulic support is one of the most important pieces of equipment in fully mechanized coal mining, and its stability and reliability will have a direct impact on fully mechanized coal mining. In order to deeply elucidate the dynamic working characteristics of a
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A hydraulic support is one of the most important pieces of equipment in fully mechanized coal mining, and its stability and reliability will have a direct impact on fully mechanized coal mining. In order to deeply elucidate the dynamic working characteristics of a hydraulic support during lifting, lowering, and moving, and to provide theoretical support for further optimizing the stability and reliability of a hydraulic support, the dynamic characteristics of a hydraulic support are studied in this paper. Firstly, in order to study the dynamic working characteristics of hydraulic support lifting, a rigid–flexible coupling dynamic simulation model of a hydraulic support is established; in order to study the dynamic working characteristics of hydraulic support moving, a microcontact dynamic model of a hydraulic support and the caving face roof and floor based on G-W contact theory is proposed, and the first rigid–flexible–mechanical–hydraulic coupling dynamic simulation system of a hydraulic support and the roof and floor of a caving face is established in the industry. Then, based on this foundation, simulation experiments are conducted for hydraulic support lifting, moving without pressure, and moving with pressure, respectively. The working characteristic parameters of the hydraulic support are collected and analyzed. The results show that working speed, working height, surface contact conditions, residual working resistance, and impact load have different effects on the stability and reliability of the hydraulic support. This study can provide in-depth technical support and theoretical guidance for understanding and improving the dynamic working characteristics of the hydraulic support.
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Open AccessArticle
Research on Displacement Sensorless Control for Bearingless Synchronous Reluctance Motor Based on the Whale Optimization Algorithm–Elman Neural Network
by
Enxiang Xu and Ruijie Zhao
Actuators 2024, 13(5), 192; https://doi.org/10.3390/act13050192 - 17 May 2024
Abstract
The unique structure of bearingless motors requires extra displacement sensors to monitor rotor movement, unlike conventional synchronous motors. However, this requirement inevitably escalates the cost and size of the motor. To address these issues, this paper proposes a novel approach: a bearingless synchronous
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The unique structure of bearingless motors requires extra displacement sensors to monitor rotor movement, unlike conventional synchronous motors. However, this requirement inevitably escalates the cost and size of the motor. To address these issues, this paper proposes a novel approach: a bearingless synchronous reluctance motor (BSRM) without displacement sensors, utilizing the whale optimization algorithm–Elman neural network (WOA-ENN). The paper firstly introduces the suspension mechanism and mathematical model of the BSRM, upon which a function containing rotor position information is constructed. Subsequently, a sensorless method based on Elman neural network (ENN) is proposed, optimized using the whale optimization algorithm (WOA). Finally, the feasibility and reliability of the proposed approach are validated through simulations and experiments.
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(This article belongs to the Section Control Systems)
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Retrofitting Battery Electric Machinery with Unchanged Hydraulic System and Enhanced Control Strategies
by
Marco Ferrari, Daniele Beltrami and Stefano Uberti
Actuators 2024, 13(5), 191; https://doi.org/10.3390/act13050191 - 16 May 2024
Abstract
The push for environmental sustainability has accelerated the acceptance of electric vehicles, as well as the exploration of electrified Non-Road Mobile Machinery. This study emphasizes the challenges of electrifying off-highway machinery, which include the many machinery layouts and the presence of Small- and
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The push for environmental sustainability has accelerated the acceptance of electric vehicles, as well as the exploration of electrified Non-Road Mobile Machinery. This study emphasizes the challenges of electrifying off-highway machinery, which include the many machinery layouts and the presence of Small- and Medium-sized Enterprises in the market. Recognizing the barriers faced by these companies, this paper shows how modeling and simulation can be effective tools for system integration and control optimization, even when lacking extensive expertise in the topic. However, it emphasizes the need for user-friendly modeling tools and methods adaptable to the operational needs of Small- and Medium-sized Enterprises. This study presents a case study of a retrofitted battery-electric hydraulic material handler. The machinery is simulated using Simscape, and the accuracy of the model is confirmed through experimental validation. By simulating a rational duty cycle, this study proposes two solutions for performance enhancement while maintaining the integrity of the hydraulic system. These solutions offer a balanced compromise between energy consumption and productivity and a novel control algorithm to minimize energy consumption. Most importantly, the two proposed solutions can be easily switched by the operator, which can decide to favor productivity over energy saving based on driving needs.
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(This article belongs to the Section Control Systems)
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Research on Multi-Mode Control of Electro-Hydraulic Variable Displacement Pump Driven by Servo Motor
by
Zhiqiang Zhang, Yupeng Yan, Lin Li, Qun Chao, Kunshan Jin and Zhiqi Liu
Actuators 2024, 13(5), 190; https://doi.org/10.3390/act13050190 - 15 May 2024
Abstract
The electro-hydraulic power source with an electro-hydraulic variable pump driven by a servo motor is suitable for electrified construction machinery. To achieve better energy efficiency in different working conditions, the multi-mode control scheme was proposed for the electro-hydraulic power source. The control scheme
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The electro-hydraulic power source with an electro-hydraulic variable pump driven by a servo motor is suitable for electrified construction machinery. To achieve better energy efficiency in different working conditions, the multi-mode control scheme was proposed for the electro-hydraulic power source. The control scheme includes pressure control, flow control, and torque control modes. The switching rule among the three control modes was formulated based on the minimum pump pressure. The fuzzy PID controller was designed, and a composite flow regulation strategy was formulated, including the load-sensitive adaptive displacement regulation and servo motor variable speed regulation. The AMESim-Simulink co-simulation model of multi-mode control was established. The test platform was built, and the experimental study was carried out. The results indicate that the fuzzy PID control has a shorter response time and a more stable control effect compared with PID control. Additionally, the composite flow regulation strategy improves the flow regulation range by 36% and reduces the flow overshoot by 20% compared with the load-sensitive adaptive displacement regulation. As the main control valve received an opening step signal, the full flow regulation (7~81 L/min) of the power source took approximately 0.5 s to rise and 0.2 s to fall. The relative error of pressure difference for the main control valve was 0.63%. When receiving the pressure and torque step signal, the pump pressure and pump input torque both took approximately 0.45 s to rise and 0.2 s to fall. The relative errors of pump pressure and torque control were 0.2% and 0.16%, respectively. In the multi-mode control, the electro-hydraulic power source could switch smoothly between flow control mode, pressure control mode, and torque control mode. These results provide a reference for the multi-mode control of an electro-hydraulic power source with an electro-hydraulic variable pump driven by a servo motor.
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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Sequential Optimal Trajectory Planning Scheme for Robotic Manipulators along Specified Path Based on Direct Collocation Method
by
Ziyao Xiong, Jianwan Ding, Liping Chen, Yu Chen and Dong Yan
Actuators 2024, 13(5), 189; https://doi.org/10.3390/act13050189 - 15 May 2024
Abstract
Robotic manipulators play a pivotal role in modern intelligent manufacturing and unmanned production systems, often tasked with executing specific paths accurately. However, the input of the robotic manipulators is trajectory which is a path with time information. The resulting core technology is trajectory
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Robotic manipulators play a pivotal role in modern intelligent manufacturing and unmanned production systems, often tasked with executing specific paths accurately. However, the input of the robotic manipulators is trajectory which is a path with time information. The resulting core technology is trajectory planning methods which are broadly classified into two categories: maximum velocity curve (MVC) methods and multiphase direct collocation (MPDC) methods. This paper concentrates on addressing challenges associated with the latter methods. In MPDC methods, the solving efficiency and accuracy are greatly influenced by the number of discretization nodes. When dealing with systems with complex dynamics, such as robotic manipulators, striking a balance between solving time and path discretization errors becomes crucial. We use a mesh refinement (MR) algorithm to find a suitable number of nodes under the premise of ensuring the path discretization error. So, the actual device can effectively implement the planned solutions. Nonetheless, the conventional application of the MR algorithm requires solving the original problem in each iteration; these processes are extremely time-consuming and may fail to solve when dealing with a complex dynamic system. As a result, we propose a sequential optimal trajectory planning scheme to solve the problem efficiently by dividing the original optimal control (OC) problem into two stages: path planning (PP) and trajectory planning (TP). In the PP stage, we employ a DC method based on arc length and an MR algorithm to identify key nodes along the specified path. This aims to minimize the approximation error introduced during discretization. In the TP stage, the identified key nodes serve as boundary conditions for an MPDC method based on time. This facilitates the generation of an optimal trajectory that maximizes motion performance, considering constant velocity in Cartesian space and dynamic constraints while keeping the path discretization error. Simulation and experiment are conducted with a six-axis robotic manipulator, ROCR6, and show significant potential for a wide range of applications in robotics.
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(This article belongs to the Section Actuators for Robotics)
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Decentralized Output-Feedback Adaptive Event-Triggered Control for Interconnected Nonlinear Delay Systems with Actuator Failures
by
Wenmin He, Yu Liu and Quanling Zhang
Actuators 2024, 13(5), 188; https://doi.org/10.3390/act13050188 - 15 May 2024
Abstract
This paper investigates decentralized adaptive event-triggered fault-tolerant control for interconnected nonlinear delay systems with actuator failures. The actuator failures suffered include loss of effectiveness and bias faults. A control scheme based on the K-filter is proposed, which effectively compensates for the effects of
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This paper investigates decentralized adaptive event-triggered fault-tolerant control for interconnected nonlinear delay systems with actuator failures. The actuator failures suffered include loss of effectiveness and bias faults. A control scheme based on the K-filter is proposed, which effectively compensates for the effects of unknown actuator failures. A hyperbolic tangent function and neural network are introduced to approximate the unknown interconnection function and nonlinear delay function. By introducing the dynamic surface control method, the “explosion of complexity” issue is addressed. Furthermore, our proposed controller can ensure that all states of the corresponding closed-loop system are semi-globally uniformly ultimately bounded and that the tracking error can converge to a small neighborhood of zero. Meanwhile, Zeno behavior can be effectively avoided. Finally, the validity of the proposed control scheme is verified using a simulation example.
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(This article belongs to the Section Control Systems)
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Open AccessArticle
Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers
by
Mark Henkenjohann, Udo Nolte, Fabian Sion, Christian Henke and Ansgar Trächtler
Actuators 2024, 13(5), 187; https://doi.org/10.3390/act13050187 - 13 May 2024
Abstract
Incremental nonlinear dynamic inversion (INDI) is a widely used approach to controlling UAVs with highly nonlinear dynamics. One key element of INDI-based controllers is the control allocation realizing pseudo controls using available actuators. However, the tracking of commanded pseudo controls is not the
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Incremental nonlinear dynamic inversion (INDI) is a widely used approach to controlling UAVs with highly nonlinear dynamics. One key element of INDI-based controllers is the control allocation realizing pseudo controls using available actuators. However, the tracking of commanded pseudo controls is not the only objective considered during control allocation. Since the approach only works locally due to linearization and the solution is often ambiguous, additional aspects like control efforts or penalizing the deviation of certain states must be considered. Conducting the control allocation by solving a quadratic program this results in a considerable number of weighting parameters, which must be tuned during control design. Currently, this is conducted manually and is therefore time consuming. An automated approach for tuning these parameters is therefore highly beneficial. Thus, this paper presents and evaluates a model-based approach automatically tuning the control allocation parameters of a tiltrotor VTOL using an optimization algorithm. This optimization algorithm searches for optimal parameters minimizing a cost functional that reflects the design target. This cost functional is calculated based on a test mission for the VTOL which is conducted within a simulation environment. The test mission represents the common operating range of the VTOL. The simulation environment consists of an aircraft model as well as a model of the INDI-based controller which is dependent on the control allocation parameters. On this basis, model-based optimization is conducted and the optimal parameters are identified. Finally, successful real-world tests on a 4-degrees-of-freedom testbench using the identified parameters are presented. Since the control allocation parameters can significantly influence the aircraft’s stability, the 4-DOF testbench for the aircraft is required for rapid validation of the parameters at a minimum amount of risk.
Full article
(This article belongs to the Special Issue Flight Control Systems and Dynamic Simulation for Aerospace Applications)
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Open AccessArticle
Effect of Structural Parameters on Output Characteristics of a Novel Self-Supplied Aviation Intelligent Pump
by
Xudong Han, Yongling Fu, Yan Wang, Feixiang Yan and Liming Yu
Actuators 2024, 13(5), 186; https://doi.org/10.3390/act13050186 - 13 May 2024
Abstract
The aviation intelligent pump system is an effective solution to aircraft hydraulic systems’ inefficient power consumption and temperature increase. A self-supplied aviation intelligent pump (SAIP) has a high power-to-weight ratio and compact structure, making it the optimal choice for an intelligent pump. To
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The aviation intelligent pump system is an effective solution to aircraft hydraulic systems’ inefficient power consumption and temperature increase. A self-supplied aviation intelligent pump (SAIP) has a high power-to-weight ratio and compact structure, making it the optimal choice for an intelligent pump. To analyze the output characteristics of a novel aviation intelligent pump, it is crucial to establish an accurate mathematical model that describes its dynamic characteristics. This can be achieved by analyzing the working principle and exploring the influence of critical parameters. The paper introduces the composition and working principle of a self-supplied electro-hydraulic servo variable displacement pump. It then establishes a mathematical model of the whole pump, with a detailed analysis and modeling of the critical variable mechanism and the swash plate assembly’s load moment. A simulation model was created to examine the impact of crucial structural parameters, such as the offset spring’s stiffness and control piston’s diameter, on the output characteristics of the intelligent pump. An experimental platform was also constructed, and the experimental results confirm the accuracy of the SAIP model presented in this paper. The investigation of the output characteristics fully reveals the dynamic performance of the SAIP. This provides the basis for the subsequent design of high-performance flow and pressure control strategies and aids in researching intelligent aircraft hydraulic systems.
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(This article belongs to the Special Issue Flight Control Systems and Dynamic Simulation for Aerospace Applications)
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Open AccessArticle
Overvoltage Avoidance Control Strategy for Braking Process of Brushless DC Motor Drives with Small DC-Link Capacitance
by
Wei Chen, Jialong Wu, Xinmin Li and Chen Li
Actuators 2024, 13(5), 185; https://doi.org/10.3390/act13050185 - 13 May 2024
Abstract
Single-phase input rectifier brushless DC motor drives with a small film capacitor have many advantages, such as high power density and high reliability. However, when the motor system operates in regenerative braking mode, the dc-link capacitor with reduced capacitance may suffer from overvoltage
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Single-phase input rectifier brushless DC motor drives with a small film capacitor have many advantages, such as high power density and high reliability. However, when the motor system operates in regenerative braking mode, the dc-link capacitor with reduced capacitance may suffer from overvoltage without adding additional hardware circuits. At the same time, the braking torque control of the motor will be affected by speed variations. In order to ensure smooth and reliable operation of the motor system, an anti-overvoltage braking torque control method is proposed in this article. The relationship among the dc-link capacitance, the dc-link capacitor voltage, and the speed during regenerative braking is analyzed quantitatively, and the speed at which the regenerative braking is switched to the plug braking is obtained, which in turn consumes the capacitor energy to avoid dc-link overvoltage. Additionally, based on the relationship between the controllability of the braking torque and the speed, a reference value of the braking current that matches the speed is designed. The proposed method makes use of the capacitor’s energy storage during regenerative braking. Meanwhile, it mitigates the impact of motor speed on braking torque. Finally, the effectiveness of the proposed method is verified on a motor platform equipped with the dc-link film capacitor.
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(This article belongs to the Special Issue Power Electronics and Actuators)
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Electromagnetic Torque Components Analysis of Ultra-High-Speed Permanent-Magnet Synchronous Motor for Fuel Cell Air Compressor
by
Jiaming Zhou, Jinming Zhang, Fengyan Yi, Donghai Hu, Caizhi Zhang, Yanzhao Li, Zhiming Zhang, Guangping Wu and Jinxiang Song
Actuators 2024, 13(5), 184; https://doi.org/10.3390/act13050184 - 12 May 2024
Abstract
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The ultra-high-speed electric air compressor (UHSEAC) is affected by the electromagnetic torque components of the ultra-high-speed permanent magnet synchronous motor (UHSPMSM) during wide-range speed regulation, resulting in intense speed fluctuation. Electromagnetic torque components are generated by the effects of permanent magnet field harmonics,
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The ultra-high-speed electric air compressor (UHSEAC) is affected by the electromagnetic torque components of the ultra-high-speed permanent magnet synchronous motor (UHSPMSM) during wide-range speed regulation, resulting in intense speed fluctuation. Electromagnetic torque components are generated by the effects of permanent magnet field harmonics, stator slotting, and current harmonics. It is very important to conduct simulation comparisons and theoretical descriptions of different sources of pulsation factors. In this paper, firstly, the electromagnetic torque model of UHSPMSM with a rated speed of 80,000 rpm is constructed and verified by an experimental bench. Secondly, the electromagnetic torque components of UHSPMSM are extracted on the basis of the electromagnetic torque model. Finally, the electromagnetic torque components’ characteristic law is investigated under different ultra-high-speed operating conditions. The results show that under ultra-high-speed operation, the frequency and amplitude of electromagnetic torque components become larger with increasing speed. And the amplitude of electromagnetic torque components becomes larger with increasing torque. This paper constructs the observation object of the high-frequency state observer and does the preliminaries for the design of the UHSEAC controller.
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Open AccessArticle
The Effect of Arm Movements on the Dynamics of the Wheelchair Frame during Manual Wheelchair Actuation and Propulsion
by
Franz Konstantin Fuss, Adin Ming Tan and Yehuda Weizman
Actuators 2024, 13(5), 183; https://doi.org/10.3390/act13050183 - 11 May 2024
Abstract
Wheelchair propulsion and actuation are influenced by the moving masses of the wheelchair user; however, the extent of this effect is still unclear. The main evidence of this effect is that the speed of the wheelchair frame continues to increase after the end
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Wheelchair propulsion and actuation are influenced by the moving masses of the wheelchair user; however, the extent of this effect is still unclear. The main evidence of this effect is that the speed of the wheelchair frame continues to increase after the end of the push phase. The wheelchair’s speed was measured using IMUs and the duration of the push period was recorded using miniaturised pressure sensors attached to the driver’s middle fingers. The velocity and acceleration were determined for various average stroke cycle speeds to determine the speed dependency of the acceleration. The wheelchair was then mounted on a force plate to measure the inertial forces of the hands moving back and forth. The aerodynamic drag and rolling resistance forces were determined from coast-down experiments. Based on the measured forces, the behaviour of the force and velocity profiles was finally modelled by gradually reducing the mass of the arms and thus their inertial force. The results showed that the wheelchair is accelerated throughout the push phase (except for a temporary deceleration in the middle of the push phase at higher velocities), and that this acceleration continues well after the push phase. In the second half of the recovery phase, the wheelchair decelerates. The horizontal inertial forces measured on the force plate are predominantly negative in the push phase and in the second half of the recovery phase, and positive in the first half of the push phase, and their impulse is zero due to the conservation of momentum. Modelling the wheelchair with moving masses showed that reducing the horizontal inertial forces has no effect on the driver’s propulsive force but reduces the velocity fluctuations. The main conclusion of this research is that the wheelchair user’s power should be calculated only from the pure propulsive force that is required in the push phase to overcome the dissipative forces and that enables the gain or loss in speed per stroke cycle, but not directly from the measured velocity.
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(This article belongs to the Special Issue Rehabilitation Robots and Assistive Devices: A Special Issue in Honor of Prof. Dr. Rory A. Cooper)
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