Actuators

15 pages, 3297 KiB

Open AccessArticle

Speed and Energy Efficiency of a Fish Robot Featuring Exponential Patterns of Control

by Ivan Tanev

Actuators 2025, 14(3), 119; https://doi.org/10.3390/act14030119 - 28 Feb 2025

Fish in nature have evolved more efficient swimming capabilities compared to that of propeller-driven autonomous underwater vehicles. Motivated by such knowledge, we discuss a bionic (bio-memetic) autonomous underwater vehicle—a fish robot—that mimics the swimming of rainbow trout (Oncorhynchus mykiss) in nature. [...] Read more.

Fish in nature have evolved more efficient swimming capabilities compared to that of propeller-driven autonomous underwater vehicles. Motivated by such knowledge, we discuss a bionic (bio-memetic) autonomous underwater vehicle—a fish robot—that mimics the swimming of rainbow trout (Oncorhynchus mykiss) in nature. The robot consists of three (anterior, posterior, and tail) segments, connected via two (anterior and posterior) actuated hinge joints. We divided the half-period of undulation of the robot into two phases—thrusting and braking. In addition, we hypothesized that an asymmetric duration—a short period of thrusting and a long period of braking—implemented as an exponential (rather than “canonical”, sinusoidal) control would favorably affect the net propulsion of these two phases. The experimental results verified that, compared to sinusoidal undulation, the proposed exponential control results in increased speed of the robot between 1.1 to 4 times in the range of frequencies of undulation between 0.4 Hz and 2 Hz, and improved energy efficiency from 1.1 to 3.6 times in the same frequency range. Full article

(This article belongs to the Section Actuators for Robotics)

26 pages, 5898 KiB

Open AccessArticle

Research on the Impact of the Slider on the Aerodynamic Characteristics of a Terrestrial–Aerial Spherical Robot

by Dongshuai Huo, Hanxu Sun, Xiaojuan Lan and Minggang Li

Actuators 2025, 14(3), 118; https://doi.org/10.3390/act14030118 - 27 Feb 2025

Abstract

This research introduces the first design concept for a ducted coaxial-rotor amphibious spherical robot (BYQ-A1), utilizing the principle of variable mass control. It investigates whether the BYQ-A1’s variable-mass slider has a certain regularity in its impact on the aerodynamic properties of the BYQ-A1. [...] Read more.

This research introduces the first design concept for a ducted coaxial-rotor amphibious spherical robot (BYQ-A1), utilizing the principle of variable mass control. It investigates whether the BYQ-A1’s variable-mass slider has a certain regularity in its impact on the aerodynamic properties of the BYQ-A1. Utilizing the Blade Element Momentum Theory (BEM) and Wall Jet Theory, an aerodynamic calculation model for the BYQ-A1 is established. An orthogonal experimental method is used to conduct tests on the impact of the variable-mass slider on the aerodynamic properties of the ducted coaxial-rotor system and validate the effectiveness of the aerodynamic calculation model. The results show that the slider generates an internal ground effect and ceiling effect within the BYQ-A1 that enhance the lift of the upper and lower rotors when the robot is equipped with it. The increased total lift compensates for the additional aerodynamic drag caused by the presence of the slider. This novel finding provides guidance for the subsequent optimization design and control method research of the BYQ-A1 and also offers valuable references for configuration schemes that incorporate necessary devices between coaxial dual rotors. Full article

(This article belongs to the Section Actuators for Robotics)

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19 pages, 21047 KiB

Open AccessArticle

Real-Time Localization for an AMR Based on RTAB-MAP

by Chih-Jer Lin, Chao-Chung Peng and Si-Ying Lu

Actuators 2025, 14(3), 117; https://doi.org/10.3390/act14030117 - 27 Feb 2025

Abstract

This study aimed to develop a real-time localization system for an AMR (autonomous mobile robot), which utilizes the Robot Operating System (ROS) Noetic version in the Ubuntu 20.04 operating system. RTAB-MAP (Real-Time Appearance-Based Mapping) is employed for localization, integrating with an RGB-D camera [...] Read more.

This study aimed to develop a real-time localization system for an AMR (autonomous mobile robot), which utilizes the Robot Operating System (ROS) Noetic version in the Ubuntu 20.04 operating system. RTAB-MAP (Real-Time Appearance-Based Mapping) is employed for localization, integrating with an RGB-D camera and a 2D LiDAR for real-time localization and mapping. The navigation was performed using the A* algorithm for global path planning, combined with the Dynamic Window Approach (DWA) for local path planning. It enables the AMR to receive velocity control commands and complete the navigation task. RTAB-MAP is a graph-based visual SLAM method that combines closed-loop detection and the graph optimization algorithm. The maps built using these three methods were evaluated with RTAB-MAP localization and AMCL (Adaptive Monte Carlo Localization) in a high-similarity long corridor environment. For RTAB-MAP and AMCL methods, three map optimization methods, i.e., TORO (Tree-based Network Optimizer), g2o (General Graph Optimization), and GTSAM (Georgia Tech Smoothing and Mapping), were used for the graph optimization of the RTAB-MAP and AMCL methods. Finally, the TORO, g2o, and GTSAM methods were compared to test the accuracy of localization for a long corridor according to the RGB-D camera and the 2D LiDAR. Full article

(This article belongs to the Special Issue Actuators in Robotic Control—3rd Edition)

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17 pages, 5063 KiB

Open AccessArticle

Observer-Based Adaptive Robust Force Control of a Robotic Manipulator Integrated with External Force/Torque Sensor

by Zixuan Huo, Mingxing Yuan, Shuaikang Zhang and Xuebo Zhang

Actuators 2025, 14(3), 116; https://doi.org/10.3390/act14030116 - 27 Feb 2025

Abstract

Maintaining precise interaction force in uncertain environments characterized by unknown and varying stiffness or location is significantly challenging for robotic manipulators. Existing approaches widely employ a two-level control structure in which the higher level generates the command motion of the lower level according [...] Read more.

Maintaining precise interaction force in uncertain environments characterized by unknown and varying stiffness or location is significantly challenging for robotic manipulators. Existing approaches widely employ a two-level control structure in which the higher level generates the command motion of the lower level according to the force tracking error. However, the low-level motion tracking error is generally ignored completely. Recognizing this limitation, this paper first formulates the low-level motion tracking error as an unknown input disturbance, based on which a dynamic interaction model capturing both structured and unstructured uncertainties is developed. With the developed interaction model, an observer-based adaptive robust force controller is proposed to achieve accurate and robust force modulation for a robotic manipulator. Alongside the theoretical stability analysis, comparative experiments with the classical admittance control (AC), the adaptive variable impedance control (AVIC), and the adaptive force tracking admittance control based on disturbance observer (AFTAC) are conducted on a robotic manipulator across four scenarios. The experimental results demonstrate the significant advantages of the proposed approach over existing methods in terms of accuracy and robustness in interaction force control. For instance, the proposed method reduces the root mean square error (RMSE) by

91.3 %

,

87.2 %

, and

75.5 %

in comparison to AC, AVIC, and AFTAC, respectively, in the experimental scenario where the manipulator is directed to follow a time-varying force while experiencing significant low-level motion tracking errors. Full article

(This article belongs to the Special Issue Motion Planning, Trajectory Prediction, and Control for Robotics)

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18 pages, 5988 KiB

Open AccessArticle

Nonlinear Adaptive Control of Maglev System Based on Parameter Identification

by Haiyan Qiang, Sheng Qiao, Hengyue Huang, Ping Cheng and Yougang Sun

Actuators 2025, 14(3), 115; https://doi.org/10.3390/act14030115 - 26 Feb 2025

Abstract

To address the nonlinearity and control problems of the Maglev system caused by external disturbances and internal factors of the system, this study first established a kinematic model of a single-point levitation system. Secondly, based on the nonlinear characteristics of the kinematic model, [...] Read more.

To address the nonlinearity and control problems of the Maglev system caused by external disturbances and internal factors of the system, this study first established a kinematic model of a single-point levitation system. Secondly, based on the nonlinear characteristics of the kinematic model, Gaussian noise was introduced into the model as input disturbance, and a neural network was used to train the constructed model. A nonlinear autoregressive model with exogenous inputs was constructed, and the Recursive Least Squares method with Forgetting Factor (RLS-FF) was used to perform parameter identification on the levitation system by combining the training data, further constructing an accurate model of the levitation system. Then, based on the accurate model of the levitation system, the backstepping method was adopted to design an adaptive controller for the levitation system, and its stability was verified. Simulation analysis was conducted on the MATLAB/Simulink platform, and comparisons were made with the LQR control method and the Fuzzy-PID control method that verified that the designed controller had a faster response speed and better self-regulation ability. At the same time, interference signals were introduced into the simulation to simulate the actual scene, and the good anti-interference ability and adaptive performance of the designed controller were further verified. Full article

(This article belongs to the Special Issue Advanced Theory and Application of Magnetic Actuators—2nd Edition)

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18 pages, 3963 KiB

Open AccessArticle

Design of Automatic Landing System for Carrier-Based Aircraft Based on Adaptive Fuzzy Sliding-Mode Control

by Haotian Zhang, Ruoheng Ma, Zhenlin Xing and Jianliang Ai

Actuators 2025, 14(3), 114; https://doi.org/10.3390/act14030114 - 26 Feb 2025

Abstract

Carrier-based aircraft (CBA) landing involves complex system engineering characterized by strong non-linearity, significant coupling and susceptibility to environmental disturbances. To address uncertainties in parameters, carrier air-wake disturbances and other challenges inherent to CBA landing, this paper presents a longitudinal automatic landing system based [...] Read more.

Carrier-based aircraft (CBA) landing involves complex system engineering characterized by strong non-linearity, significant coupling and susceptibility to environmental disturbances. To address uncertainties in parameters, carrier air-wake disturbances and other challenges inherent to CBA landing, this paper presents a longitudinal automatic landing system based on adaptive fuzzy sliding-mode control. This system was developed to improve control accuracy and stability during the critical landing phase. Furthermore, this paper analyzes components of carrier air-wake and motion conditions for ideal landing points on the carrier deck, and designs a sliding-mode surface with the integral term. An adaptive fuzzy sliding-mode controller based on equivalent and switching controls is constructed, which exhibits stability under the Lyapunov stability condition. Moreover, a Monte Carlo simulation method is employed to verify the simulation of the automatic landing control system. Owing to its impressive dynamic performance and robustness, the proposed control method can track expected values with high accuracy in a complex environment, thereby satisfying the CBA landing requirements. Full article

(This article belongs to the Section Aerospace Actuators)

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19 pages, 6456 KiB

Open AccessArticle

Multi-Signal Induction Motor Broken Rotor Bar Detection Based on Merged Convolutional Neural Network

by Tianyi Wang, Shiguang Wen, Shaotong Sheng and Huimin Ma

Actuators 2025, 14(3), 113; https://doi.org/10.3390/act14030113 - 25 Feb 2025

Abstract

Motor fault detection plays a vital role in industrial maintenance. Timely detection of faults in their early stages can prevent catastrophic consequences and reduce maintenance costs. Traditional methods face challenges in motor broken rotor bar (BRB) detection: model-driven methods are difficult to apply [...] Read more.

Motor fault detection plays a vital role in industrial maintenance. Timely detection of faults in their early stages can prevent catastrophic consequences and reduce maintenance costs. Traditional methods face challenges in motor broken rotor bar (BRB) detection: model-driven methods are difficult to apply accurately in complex and changing environments, while data-driven methods usually require sophisticated feature extraction and classification processes. In this paper, we propose a novel non-invasive fault detection method. The method preprocesses motor currents by Hilbert-Huang Transform (HHT) and Park’s Vector Modulus (PVM) and then uses a merged convolutional neural network (CNN) for classification. This experiment investigates the detection of broken rotor bars of motors with different loads (25%, 50%, 75%, and 100% of rated load) and different fault levels (Normal, 1BRB, 2BRB, 3BRB, and 4BRB). The results show that the model’s classification accuracy exceeds 95% under various operating conditions and can maintain high accuracy under low load conditions, thus addressing the limitations faced by existing methods. In addition, it is computationally efficient and can guarantee high real-time performance. This method combines advanced signal processing techniques and deep learning algorithms to provide a practical solution for motor broken rotor bar detection. Full article

(This article belongs to the Section Actuators for Manufacturing Systems)

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21 pages, 5037 KiB

Open AccessFeature PaperArticle

SNN-Based Surrogate Modeling of Electromagnetic Force and Its Application in Maglev Vehicle Dynamics Simulation

by Yang Feng, Chunfa Zhao, Xin Liang and Zhan Bai

Actuators 2025, 14(3), 112; https://doi.org/10.3390/act14030112 - 25 Feb 2025

Abstract

The majority of electromagnetic force calculation models employed in maglev vehicle system dynamics focus exclusively on vertical and lateral movement while neglecting the nonlinear magnetization properties of ferromagnetic materials. This oversight leads to discrepancies between the dynamics simulations and actual conditions. To enhance [...] Read more.

The majority of electromagnetic force calculation models employed in maglev vehicle system dynamics focus exclusively on vertical and lateral movement while neglecting the nonlinear magnetization properties of ferromagnetic materials. This oversight leads to discrepancies between the dynamics simulations and actual conditions. To enhance the accuracy of dynamics simulations and evaluate the performance of maglev vehicle systems under various operational conditions, it is imperative to identify an electromagnetic force calculation model that combines accuracy and applicability. To address this objective, this paper examines a U-shaped electromagnet in medium–low-speed maglev vehicles as a case study. It constructs a spatial electromagnetic force calculation surrogate model using a Shallow Neural Network. The surrogate model is capable of accurately calculating electromagnetic forces considering relative position deviations in the lateral, vertical, rolling, pitching, and shaking directions. Moreover, it can be integrated into vehicle system dynamics simulations. The accuracy of the electromagnetic force calculation surrogate model is confirmed by extensive comparisons with finite element simulation results across various conditions, achieving an impressive concordance rate of up to 95%. An illustrative application of the electromagnetic force calculation surrogate model in maglev vehicle system dynamics simulation is provided to showcase its practical utility. Full article

(This article belongs to the Special Issue Advanced Theory and Application of Magnetic Actuators—2nd Edition)

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16 pages, 2006 KiB

Open AccessArticle

Research on Risk Analysis Method of Maglev Train Suspension System Based on Fuzzy Multi-Attribute Decision-Making

by Xiang Chen, Xiaolong Li and Yilu Feng

Actuators 2025, 14(3), 111; https://doi.org/10.3390/act14030111 - 25 Feb 2025

Abstract

As a new type of rail transit vehicle, maglev trains have extremely high requirements for safety and reliability. With the gradual commercial operation of maglev trains, how to scientifically and effectively assess the safety and analyze the risks of train equipment has become [...] Read more.

As a new type of rail transit vehicle, maglev trains have extremely high requirements for safety and reliability. With the gradual commercial operation of maglev trains, how to scientifically and effectively assess the safety and analyze the risks of train equipment has become an urgent issue to be addressed. Against the backdrop of the practical application of maglev train projects, this paper integrates domestic and international risk analysis models, proposes the steps for conducting the risk analysis of maglev rail transit, and establishes a risk analysis system for the entire lifecycle of maglev rail transit. Based on the results of fault analysis, a risk analysis of the levitation system is carried out. The theory of multi-attribute decision-making is studied, new risk evaluation indicators are established using triangular fuzzy numbers, the risk levels of the levitation system are determined, and the weak links within the system and the relationships between the pieces of equipment are identified. These efforts provide guidance for enhancing the safety and reliability of train equipment and for carrying out train maintenance work. Full article

(This article belongs to the Special Issue Advanced Theory and Application of Magnetic Actuators—2nd Edition)

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15 pages, 7444 KiB

Open AccessArticle

Soft Robot Workspace Estimation via Finite Element Analysis and Machine Learning

by Getachew Ambaye, Enkhsaikhan Boldsaikhan and Krishna Krishnan

Actuators 2025, 14(3), 110; https://doi.org/10.3390/act14030110 - 23 Feb 2025

Abstract

Soft robots with compliant bodies offer safe human–robot interaction as well as adaptability to unstructured dynamic environments. However, the nonlinear dynamics of a soft robot with infinite motion freedom pose various challenges to operation and control engineering. This research explores the motion of [...] Read more.

Soft robots with compliant bodies offer safe human–robot interaction as well as adaptability to unstructured dynamic environments. However, the nonlinear dynamics of a soft robot with infinite motion freedom pose various challenges to operation and control engineering. This research explores the motion of a pneumatic soft robot under diverse loading conditions by conducting finite element analysis (FEA) and using machine learning. The pneumatic soft robot consists of two parallel hyper-elastic tubular chambers that convert pneumatic pressure inputs into soft robot motion to mimic an elephant trunk and its motion. The body of each pneumatic chamber consists of a series of bellows to effectively facilitate the expansion, contraction, and bending of the body. The first chamber spans the entire length of the soft robot’s body, and the second chamber spans half of it. This unique asymmetric design enables the soft robot to bend and curl in various ways. Machine learning is used to establish a forward kinematic relationship between the pressure inputs and the motion responses of the soft robot using data from FEA. Accordingly, this research employs an artificial neural network that is trained on FEA data to estimate the reachable workspace of the soft robot for given pressure inputs. The trained neural network demonstrates promising estimation accuracy with an R-squared value of 0.99 and a root mean square error of 0.783. The workspaces of asymmetric double-chamber and single-chamber soft robots were compared, revealing that the double-chamber robot offers approximately 185 times more reachable workspace than the single-chamber soft robot. Full article

(This article belongs to the Special Issue Bio-Inspired Soft Robotics)

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24 pages, 6389 KiB

Open AccessArticle

Local Heat Transfer Analysis of Dual Sweeping Jet, Double Sweeping Jets, and Double Circular Jets Impinging at a Flat Surface

by Muhammad Zubair, Feng Ren and Xin Wen

Actuators 2025, 14(3), 109; https://doi.org/10.3390/act14030109 - 21 Feb 2025

Abstract

A sweeping jet is commonly preferred over a steady jet owing to its ability to better cool the region away from the strong core of an impinging jet. For industrial applications, it is important to study the thermal fields of oscillating jets in [...] Read more.

A sweeping jet is commonly preferred over a steady jet owing to its ability to better cool the region away from the strong core of an impinging jet. For industrial applications, it is important to study the thermal fields of oscillating jets in a multi-jet configuration to focus on the region that falls between the two consecutive fluidic oscillators and, hence, suggest a mechanism to uniformly cool the targeted flat surface. A comparative experimental study of dual sweeping jets (DSJs), double sweeping jets (DbSJs), and double circular jets (DbCJs) was conducted at different jet-to-plate spacings, various Re numbers, and three aspect ratios. The multi-circular and sweeping jets were impinged on a flat hot surface, which was heated at a constant flux of current, and thermocouples were employed to efficiently collect the time-averaged heat transfer distribution along the sweeping and transverse directions. It was determined that heat transfer, in terms of the Nusselt number, generally increased with increasing Re number and reduced the jet-to-wall spacing for the DSJ, DbSJ, and DbCJ, with some minor exceptions. The relative performance of these fluidic devices suggested that the best performance of DSJ was at small spacing and higher Re, DbSJ at moderate spacing and lower Re, and DbCJ at moderate spacing and moderate Re. The mutual comparison showed that along the sweeping motion, in the central region, DbCJ was better than both DSJ and DbSJ; in the right region, DSJ performance was far better than DbCJ and DbSJ; in the left region, DSJ was better than DbSJ when comparing the respective centers of DSJ and DbSJ. The dominance of DSJ over DbSJ at the centers of their respective bodies even extends in the transverse direction. Finally, for higher aspect ratios, the DSJ performed better in the outer regions, while the DbSJ performed well in the central region. Similarly, for both DSJ and DbSJ unanimously, the effect of changing the aspect ratio is interesting as initially, the Nu values increase for a higher aspect ratio, but by increasing the AR further, it causes a divergence of the fluidic volume from the central region to the surrounding region. Full article

(This article belongs to the Special Issue Active Flow Control: Recent Advances in Fundamentals and Applications—3rd Edition)

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59 pages, 3714 KiB

Open AccessReview

Advances in Control Techniques for Rehabilitation Exoskeleton Robots: A Systematic Review

by Gazi Mashud, SK Hasan and Nafizul Alam

Actuators 2025, 14(3), 108; https://doi.org/10.3390/act14030108 - 21 Feb 2025

Abstract

This systematic review explores recent advancements in control methods for rehabilitation exoskeleton robots, which assist individuals with motor impairments through guided movement. As robotics technology progresses, precise, adaptable, and safe control techniques have become accessible for effective human–robot interaction in rehabilitation settings. Key [...] Read more.

This systematic review explores recent advancements in control methods for rehabilitation exoskeleton robots, which assist individuals with motor impairments through guided movement. As robotics technology progresses, precise, adaptable, and safe control techniques have become accessible for effective human–robot interaction in rehabilitation settings. Key control methods, including computed torque and adaptive control, excel in managing complex movements and adapting to diverse patient needs. Robust and sliding mode controls address stability under unpredictable conditions. Traditional approaches, like PD and PID control schemes, maintain stability, performance, and simplicity. In contrast, admittance control enhances user–robot interaction by balancing force and motion. Advanced methods, such as model predictive control (MPC) and Linear Quadratic Regulator (LQR), provide optimization-based solutions. Intelligent controls using neural networks, Deep Learning, and reinforcement learning offer adaptive, patient-specific solutions by learning over time. This review provides an in-depth analysis of these control strategies by examining advancements in recent scientific literature, highlighting their potential to improve rehabilitation exoskeletons, and offering future recommendations for greater efficiency, responsiveness, and patient-centered functionality. Full article

(This article belongs to the Section Actuators for Robotics)

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16 pages, 830 KiB

Open AccessArticle

Coupled Dynamics Modeling and Validation of Maglev Vehicle and Bridge Systems

by Fei Zhou and Xiaolong Li

Actuators 2025, 14(3), 107; https://doi.org/10.3390/act14030107 - 21 Feb 2025

Abstract

To address the vehicle-bridge coupling vibration issue of the Qingyuan Maglev Tourist Line, it is necessary to establish a maglev vehicle–bridge coupling dynamics simulation model that reflects the actual line conditions. Based on the vehicle and bridge structural parameters of the Qingyuan Maglev [...] Read more.

To address the vehicle-bridge coupling vibration issue of the Qingyuan Maglev Tourist Line, it is necessary to establish a maglev vehicle–bridge coupling dynamics simulation model that reflects the actual line conditions. Based on the vehicle and bridge structural parameters of the Qingyuan Maglev Tourist Line, this paper utilizes multi-body dynamics simulation software to create a medium–low-speed maglev vehicle dynamics model, and employs finite element software to construct a bridge model. Using the modal reduction method, the bridge finite element model is imported into the vehicle dynamics model through a rigid–flex coupling interface, establishing a medium–low-speed maglev vehicle suspension system–bridge coupling dynamics model. The accuracy of the established coupling simulation model was verified by comparing the simulation data from the coupling model with the dynamic response measured data from the Qingyuan Maglev Tourist Line. Finally, the impact of different control parameters on the vehicle–bridge coupling system was calculated, and the results indicate that selecting appropriate suspension control parameters can reduce the coupling vibration response between the maglev vehicle and the bridge. The main work of this paper is closely related to engineering, modeling based on the actual maglev line’s vehicle and bridge parameters, and validating the model through the dynamic test results of the line, laying the foundation for the suppression of maglev vehicle–bridge coupling vibration and system optimization. Full article

(This article belongs to the Special Issue Advanced Theory and Application of Magnetic Actuators—2nd Edition)

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31 pages, 6718 KiB

Open AccessArticle

A Study on a Speed Regulation Method for Mining Scraper Conveyors and a Control Strategy for Permanent Magnet Drive Systems

by Xi Zhang, Mingming Ren, Hongju Wang, Hongyu Xu, Bin Shi and Miaomiao Gao

Actuators 2025, 14(3), 106; https://doi.org/10.3390/act14030106 - 21 Feb 2025

Abstract

To address the mismatch between materials and operational speed in mine scraper conveyors under time-varying load conditions, this paper proposes a methodology for the regulation of speed based on the quantity of coal transported by the scraper conveyor. Furthermore, a vector control strategy [...] Read more.

To address the mismatch between materials and operational speed in mine scraper conveyors under time-varying load conditions, this paper proposes a methodology for the regulation of speed based on the quantity of coal transported by the scraper conveyor. Furthermore, a vector control strategy for permanent magnet synchronous motors (PMSMs) is presented, underpinned by a global fast terminal sliding mode controller. Firstly, a calculation model for the real-time coal volume of the scraper conveyor was developed based on the double-end oblique cutting coal mining technology in fully mechanized mining operations. This model takes into account the operational condition of the shearer and the scraper conveyor. In addition, a graded speed regulation control method was introduced. Secondly, a global fast terminal controller was developed by integrating the features of linear and terminal sliding mode surfaces. An enhanced sliding mode vector control strategy for the permanent magnet drive motor of the scraper conveyor was subsequently proposed. Finally, a simulation and ground test were subsequently performed on the PMSM experimental bench and SGZ2×1200 scraper conveyor to validate the proposed control strategy. The results indicated that the proposed control strategy not only diminished the overshoot of the rotational speed and decreased the dynamic response time but also improved the anti-interference capabilities of the PMSM relative to the original PI control. Moreover, the ground test validated the feasibility of the suggested speed regulation method. Full article

(This article belongs to the Section Control Systems)

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26 pages, 2295 KiB

Open AccessArticle

Robust Adaptive Cascade Trajectory Tracking Control for an Aircraft Towing and Taxiing System

by Weining Huang, Pengjie Xu, Tianrui Zhao, Wei Zhang and Yanzheng Zhao

Actuators 2025, 14(3), 105; https://doi.org/10.3390/act14030105 - 20 Feb 2025

Abstract

With the rapid growth of the civil aviation industry, the aircraft towing and taxiing (ATT) system has gained significant attention in the literature. Due to its nonlinear and underactuated characteristics, the path tracking and control of the ATT system is a challenging issue. [...] Read more.

With the rapid growth of the civil aviation industry, the aircraft towing and taxiing (ATT) system has gained significant attention in the literature. Due to its nonlinear and underactuated characteristics, the path tracking and control of the ATT system is a challenging issue. Therefore, in this paper, a robust adaptive cascade control structure is proposed for the path tracking of the ATT system. Firstly, the system description is established via kinematic and dynamics modeling, and the lumped system disturbance is derived for the controller design. Next, the robust adaptive cascade control structure consisting of the adaptive MPC and the CSMC or the RASMC-based dynamics controller is designed with the application of the extended Kalman filter. The system stability in the dynamics loop is verified through the Lyapunov method. The simulation results reveal that the combination of the adaptive MPC and the RASMC can provide a more accurate tracking performance and smoother trajectories under the given disturbances and uncertainties, while both ensuring passenger comfort and meeting the civil aviation regulations, indicating its potential in practical applications. Full article

(This article belongs to the Special Issue Flight Control Systems and Dynamic Simulation for Aerospace Applications)

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25 pages, 4799 KiB

Open AccessArticle

Optimized Structural Design of a Reciprocating Wing for the Reciprocating Airfoil (RA)-Driven Vertical Take-Off and Landing (VTOL) Aircraft

by Johnson Imumbhon Okoduwa, Osezua Obehi Ibhadode and Yiding Cao

Actuators 2025, 14(3), 104; https://doi.org/10.3390/act14030104 - 20 Feb 2025

Abstract

The development of unconventional and hybrid unoccupied aerial vehicles (UAVs) has gained significant momentum in recent years, with many designs utilizing small fans or rotary blades for vertical take-off and landing (VTOL). However, these systems often inherit the limitations of traditional helicopter rotors, [...] Read more.

The development of unconventional and hybrid unoccupied aerial vehicles (UAVs) has gained significant momentum in recent years, with many designs utilizing small fans or rotary blades for vertical take-off and landing (VTOL). However, these systems often inherit the limitations of traditional helicopter rotors, including susceptibility to aerodynamic inefficiencies and mechanical issues. Additionally, achieving a seamless transition from VTOL to fixed-wing flight mode remains a significant challenge for hybrid UAVs. A novel approach is the reciprocating airfoil (RA) or reciprocating wing (RW) VTOL aircraft, which employs a fixed-wing configuration driven by a reciprocating mechanism to generate lift. The RA wing is uniquely designed to mimic a fixed-wing while leveraging its reciprocating motion for efficient lift production and a smooth transition between VTOL and forward flight. Despite its advantages, the RA wing endures substantial stress due to the high inertial forces involved in its operation. This study presents an optimized structural design of the RA wing through wing topology optimization and finite element analysis (FEA) to enhance its load-bearing capacity and stress performance. A comparative analysis with existing RA wing configurations at maximum operating velocities highlights significant improvements in the safety margin, failure criteria, and overall stress distribution. The key results of this study show an 80.4% reduction in deformation, a 43.8% reduction in stress, and a 78% improvement in safety margin. The results underscore the RA wing’s potential as an effective and structurally stable lift mechanism for RA-driven VTOL aircraft, demonstrating its capability to enhance the performance and reliability of next-generation UAVs. Full article

(This article belongs to the Special Issue Aerospace Mechanisms and Actuation—Second Edition)

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18 pages, 5366 KiB

Open AccessArticle

Regenerative Structural Fatigue Testing with Digital Displacement Pump/Motors

by Win Rampen, Marek J. Munko, Sergio Lopez Dubon and Fergus Cuthill

Actuators 2025, 14(3), 103; https://doi.org/10.3390/act14030103 - 20 Feb 2025

Abstract

Historically, a large fraction of fatigue testing of both components and structures has been performed using hydraulic actuators. These are typically driven by servo-valves, which are in themselves very inefficient. But, as most tests involve elastically stressing mechanical components, a lot of stored [...] Read more.

Historically, a large fraction of fatigue testing of both components and structures has been performed using hydraulic actuators. These are typically driven by servo-valves, which are in themselves very inefficient. But, as most tests involve elastically stressing mechanical components, a lot of stored energy could be recovered. Unfortunately, servo-valves are not regenerative—simply metering out fluid in order to relax the system prior to the start of the next cycle. There is much to be gained with a more intelligently controlled system. The FastBlade facility in Scotland uses a new type of regenerative test hydraulics. Digital displacement pump/motors (DDPMs), originated by Artemis Intelligent Power, now Danfoss Scotland, are used to load and unload the test structure directly via hydraulic rams. The DDPMs are driven by induction motors supplied by three-phase frequency converters, each with a very loose speed correction target, such that they can speed up or slow down according to the instantaneous torque exerted by the load. The rotating assembly of the induction motor and DDPM is designed to have sufficient inertia so as to function as a kinetic energy storage flywheel. The loading energy is then cyclically transferred between the rotating inertia of the motor/DDPM and the spring energy in the test structure. The electric motor provides sufficient energy to maintain the target average cyclical shaft speed of the DDPM whilst the bulk of the system energy oscillates between the two storage mechanisms. Initial tests (at low load) suggest that this technique requires only 30% of the energy previously needed. FastBlade is a unique facility built by the University of Edinburgh and Babcock, with support from the UK EPSRC, conceived as a means of testing and certifying turbine blades for marine current turbines. However, this approach can be used in any cyclical application where elastic energy is stored. Full article

(This article belongs to the Special Issue Actuation and Control in Digital Fluid Power)

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17 pages, 1151 KiB

Open AccessArticle

Numerical Analysis of a Hypersonic Body Under Thermochemical Non-Equilibrium and Different Catalytic Surface Conditions

by Odelma Teixeira and José Páscoa

Actuators 2025, 14(2), 102; https://doi.org/10.3390/act14020102 - 19 Feb 2025

Abstract

This work results from a numerical investigation of the thermochemical non-equilibrium effects on the surface properties of a hypersonic body. Non-equilibrium within an air mixture composed of 11 chemical species was considered when solving the Navier–Stokes–Fourier equations using a density-based algorithm in OpenFOAM. [...] Read more.

This work results from a numerical investigation of the thermochemical non-equilibrium effects on the surface properties of a hypersonic body. Non-equilibrium within an air mixture composed of 11 chemical species was considered when solving the Navier–Stokes–Fourier equations using a density-based algorithm in OpenFOAM. The influence of thermal and chemical non-equilibrium on the surface properties of a hypersonic double-cone test body was studied by considering two types of surfaces. It was found that the heat flux and pressure distribution along the surface are higher under non-equilibrium free-stream conditions. Unlike what was observed at the impingement point, where the vibrational non-equilibrium effects on the surface properties are almost independent of the surface type, at the stagnation point, these effects are highly dependent on the catalytic activity of the surface. At the stagnation point, the vibrational non-equilibrium effects are more pronounced on a fully catalytic surface than on a non-catalytic surface. Under the studied conditions, the vibrational non-equilibrium reduces the heat flux by 18% for a non-catalytic surface, while for a fully catalytic surface, it reduces the heat flux by 38%. Additionally, the presence of vibrational non-equilibrium in the free-stream reduces the pressure by 24% for a non-catalytic surface, while for a fully catalytic surface, it is reduced by 42%. Full article

(This article belongs to the Special Issue Flow Control and Beyond Enhancing Performance and Energy Efficiency in Complex Fluid System)

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23 pages, 8016 KiB

Open AccessArticle

Flow Characteristics of a Dual Sweeping Jet Impinging on a Flat Surface

by Muhammad Zubair and Xin Wen

Actuators 2025, 14(2), 101; https://doi.org/10.3390/act14020101 - 19 Feb 2025

Abstract

The dual sweeping jet (DSJ)-producing fluidic oscillator is a novel device developed by sharing a feedback channel between two standard fluidic oscillators. This device produces a pair of sweeping jets in the outer domain and has the potential to be used for the [...] Read more.

The dual sweeping jet (DSJ)-producing fluidic oscillator is a novel device developed by sharing a feedback channel between two standard fluidic oscillators. This device produces a pair of sweeping jets in the outer domain and has the potential to be used for the better and uniform treatment of impinged surfaces. Therefore, it is important to investigate the extent of the synchronicity of these jets at different Re numbers and various aspect ratios in outer domains, and to comprehend their internal switching mechanism simultaneously. The time-averaged flow fields demonstrated that, at lower Re numbers, both sweeping jets were symmetric about their centerlines and the cores were strong. The strength of the cores deteriorated at higher Re numbers, and the flare regions became wider and stronger. Moreover, the transverse velocities pulled the sweeping jets away from the origin and a high upwash flow formed in-between the jets. The phase-averaged flow fields vividly illustrated the sharing mechanism between the two power nozzles through the formation of left- and right-loops consecutively in the shared feedback channel. These primary loops generated an auxiliary mechanism on both sides of a fluidic oscillator, which actually controlled the synchronicity of the two sweeping jets in the outer domain. Additionally, they also showed that both jets are properly synchronized and have strong cores at lower Re numbers. However, at higher Re numbers, greater velocities were found in the switching and sweeping mechanisms which caused asynchrony between the sweeping jets but nonetheless impinged a larger area and covered the region in-between the jets properly. The power nozzles were also found to self-feed themselves due to the hindrance at the ‘outer shoulders’ of this fluidic oscillator and hence caused the premature formation of a recirculation bubble of vorticity between the power nozzle and its respective outer island. Lastly, the aspect ratio analysis revealed that the asynchrony of DSJ at higher Re numbers can be mitigated by reducing the aspect ratio. Full article

(This article belongs to the Special Issue Active Flow Control: Recent Advances in Fundamentals and Applications—3rd Edition)

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