Actuators

12 pages, 1881 KiB

Open AccessArticle

A Non-Linear Offset-Free Model Predictive Control Design Approach

by Haoran Zhang and Emmanuel Prempain

Actuators 2024, 13(8), 322; https://doi.org/10.3390/act13080322 - 22 Aug 2024

Cited by 1 | Viewed by 513

This paper presents a non-linear model predictive control approach for offset-free tracking and the rejection of piece-wise constant disturbances. The approach involves augmenting the system’s state vector with the integral of the tracking error, enabling the design of a non-linear model predictive controller [...] Read more.

This paper presents a non-linear model predictive control approach for offset-free tracking and the rejection of piece-wise constant disturbances. The approach involves augmenting the system’s state vector with the integral of the tracking error, enabling the design of a non-linear model predictive controller for this augmented system. Nominal closed-loop stability is enforced thanks to a terminal equality constraint and proven by a Lyapunov argument. Compared to the existing offset-free approaches in the literature, our method offers greater simplicity, as it does not rely on linear approximations of the system to control. Furthermore, it eliminates the need to estimate disturbances, a task that is especially challenging with non-linear systems. Comprehensive simulations and experimental tests are conducted according to a non-linear, coupled, two-tank laboratory experiment, demonstrating the robustness and effectiveness of the proposed approach. Full article

(This article belongs to the Section Control Systems)

► Show Figures

Figure 1

0 pages, 1772 KiB

Open AccessArticle

Optimal Searching-Based Reference Current Computation Algorithm for IPMSM Drives Considering Iron Loss

by Péter Stumpf and Tamás Tóth-Katona

Actuators 2024, 13(8), 321; https://doi.org/10.3390/act13080321 - 21 Aug 2024

Viewed by 506

Abstract

Interior permanent magnet synchronous machines (IPMSMs) are widely used as traction motors in the electric drive-train because of their high torque-per-ampere characteristics and potential for wide field weakening operation to expand the constant power range. The paper aims to introduce the most important [...] Read more.

Interior permanent magnet synchronous machines (IPMSMs) are widely used as traction motors in the electric drive-train because of their high torque-per-ampere characteristics and potential for wide field weakening operation to expand the constant power range. The paper aims to introduce the most important equations to calculate the operating trajectories of an IPMSM for optimal control. The main contribution is that the optimal operating trajectories are calculated by a feedforward, Newton–Raphson method-based searching algorithm that considers the iron loss resistance of IPMSMs. Steady-state calculations and dynamic simulation results prove the theoretical findings. Full article

(This article belongs to the Section High Torque/Power Density Actuators)

► Show Figures

Figure 1

14 pages, 6078 KiB

Open AccessArticle

Load Torque Component Extraction and Analysis of Ultra-High-Speed Electric Air Compressors for Fuel Cell Vehicles

by Jiaming Zhou, Xing Shu, Jinming Zhang, Fengyan Yi, Donghai Hu, Caizhi Zhang and Yanzhao Li

Actuators 2024, 13(8), 320; https://doi.org/10.3390/act13080320 - 21 Aug 2024

Viewed by 460

Abstract

An ultra-high-speed electric air compressor (UHSEAC) generates a load torque component during operation, leading to unstable output. As air passes through the UHSEAC, the air density changes significantly, resulting in increased uneven distribution. This causes rapid changes in gas parameters, making them difficult [...] Read more.

An ultra-high-speed electric air compressor (UHSEAC) generates a load torque component during operation, leading to unstable output. As air passes through the UHSEAC, the air density changes significantly, resulting in increased uneven distribution. This causes rapid changes in gas parameters, making them difficult to extract. Consequently, the behavior of load torque component variations under ultra-high-speed operating conditions (UHSOC) remains unclear. The influence of UHSOC on the load torque component has not been studied. In this article, the fluid model of the UHSEAC is established and verified, and the load torque component is extracted based on this model. The influence of speed and torque on the load torque component under UHSOC is then studied. The results show that the frequency of the load torque component increases by 14.29% as the speed increases from 70,000 rpm to 90,000 rpm. Additionally, as the torque increases from 1.3 Nm to 1.7 Nm, the amplitude of the load torque component increases by 69.56%. These findings provide valuable guidance for future scholars seeking to optimize UHSEAC design to reduce load torque components. Full article

► Show Figures

Figure 1

18 pages, 22431 KiB

Open AccessArticle

Designing a Robotic Gripper Based on the Actuating Capacity of NiTi-Based Shape Memory Wires

by Adrian Petru Teodoriu, Bogdan Pricop, Nicoleta-Monica Lohan, Mihai Popa, Radu Ioachim Comăneci, Ioan Doroftei and Leandru-Gheorghe Bujoreanu

Actuators 2024, 13(8), 319; https://doi.org/10.3390/act13080319 - 21 Aug 2024

Viewed by 534

Abstract

In the present study, the capacity of two commercial NiTi and NiTiCu shape memory alloy (SMA) wires to develop work-generating (WG) and constrained-recovery (CR) shape memory effects (SMEs), as well as the capacity of a commercial NiTiFe super-elastic wire to act as cold-shape [...] Read more.

In the present study, the capacity of two commercial NiTi and NiTiCu shape memory alloy (SMA) wires to develop work-generating (WG) and constrained-recovery (CR) shape memory effects (SMEs), as well as the capacity of a commercial NiTiFe super-elastic wire to act as cold-shape restoring element, have been investigated. Using differential scanning calorimetry (DSC), the reversible martensitic transformation to austenite of the three NiTi-based wires under study was emphasized by means of an endothermic minimum of the heat flow variation with temperature. NiTi and NiTiCu wire fragments were further tested for both WG-SME and CR-SME developed during the heating, from room temperature (RT) to different maximum temperatures selected from the DSC thermograms. The former tests revealed the capacity to repetitively lift various loads during repetitive heating, while the latter tests disclosed the repetitive development of shrinkage stresses during the repetitive heating of elongated wires. The tensile behavior of the three NiTi-based SMA wires was analyzed by failure and loading–unloading tests. The study disclosed the actuation capacity of NiTi and NiTiCu shape memory wires, which were able to develop work while being heated, as well as the resetting capacity of NiTiFe super-elastic wires, which can restore the initial undeformed shape of shape memory wires which soften while being cooled down. These features enable the design of a robotic gripper based on the development of NiTi-based actuators with repetitive action. Full article

(This article belongs to the Special Issue Advanced Robots: Design, Control and Application—2nd Edition)

► Show Figures

Figure 1

21 pages, 12351 KiB

Open AccessArticle

Design and Optimization of a Bennett–Spherical Scissor Mechanism Suitable for Driving Aerial–Aquatic Rotor Deformation

by Chengrong Du and Dongbiao Zhao

Actuators 2024, 13(8), 318; https://doi.org/10.3390/act13080318 - 21 Aug 2024

Viewed by 515

Abstract

This paper aims to design a deformable mechanism to drive amphibious rotor blade deform from an aerial shape to an aquatic one. The Bennett four-bar and spherical four-bar mechanisms are used as the basic units (B unit and S unit) to form the [...] Read more.

This paper aims to design a deformable mechanism to drive amphibious rotor blade deform from an aerial shape to an aquatic one. The Bennett four-bar and spherical four-bar mechanisms are used as the basic units (B unit and S unit) to form the Bennett–spherical spatial scissor unit (BS unit). By analyzing the kinematic characteristics of the BS unit, it is found that the BS unit can achieve the spatial deformation of expansion and torsion, effectively improving the rotor’s performance in water and air media. The wing rib support structure, which is fixed to the BS unit linkage, is designed. The coordinate transformation method describes the blade shape in aerial and aquatic modes using BS unit and rib parameters. To improve the rotor blade performance in air and water, the rotor blade design is carried out under the NSGA-II framework with BS parameters as the design variables. The Gaussian regression and CFD methods are applied to build a surrogate model to reduce the computational cost. The results show that the expansion–torsional deformation of the BS unit can effectively increase the air and water compatibility of the rotor blades. When the rotor is an aerial shape, the BS mechanism extends and decreases the torsion to increase the lift and efficiency. When it is deformed to an aquatic shape, the BS mechanism reduces its length and increases the torsion to reduce the torque effectively. The BS scissor unit and the design method can be effectively applied in the design of deformable rotor blades. Full article

(This article belongs to the Special Issue Advances in Dynamics and Motion Control of Unmanned Aerial/Underwater/Ground Vehicles)

► Show Figures

Figure 1

23 pages, 6212 KiB

Open AccessArticle

Research on Camera Rotation Strategies for Active Visual Perception in the Self-Driving Vehicles

by Xiangcun Kong, Shuyue Shi, Bingchen Yan, Shuzhe Si, Juan Ni, Dong Guo, Pengwei Wang, Lei Wang and Yi Xu

Actuators 2024, 13(8), 317; https://doi.org/10.3390/act13080317 - 20 Aug 2024

Viewed by 445

Abstract

Aiming at the problem of blind field of view caused by the change in the vehicle’s yaw angle when the self-driving vehicle is turning or changing lanes, this paper proposes a camera rotation strategy based on monocular active environment sensing, which realizes the [...] Read more.

Aiming at the problem of blind field of view caused by the change in the vehicle’s yaw angle when the self-driving vehicle is turning or changing lanes, this paper proposes a camera rotation strategy based on monocular active environment sensing, which realizes the detection of the blind field of view when the vehicle’s yaw angle changes in the self-driving vehicle. Based on the two-degrees-of-freedom dynamic model, the camera rotation angle control is achieved by controlling the front-wheel angle of the vehicle. A camera control module is designed using Simulink to control the camera in real-time, allowing it to rotate based on different driving scenes. The effect of obstacle detection by traditional vision sensors and active vision sensors is tested under different vehicle driving scenes. The results demonstrate that the obstacle detection effect of the camera rotation strategy based on monocular active environment perception, as designed in this paper, is better than the traditional monocular vision. Full article

► Show Figures

Figure 1

21 pages, 6058 KiB

Open AccessArticle

Synergistic Pushing and Grasping for Enhanced Robotic Manipulation Using Deep Reinforcement Learning

by Birhanemeskel Alamir Shiferaw, Tayachew F. Agidew, Ali Saeed Alzahrani and Ramasamy Srinivasagan

Actuators 2024, 13(8), 316; https://doi.org/10.3390/act13080316 - 20 Aug 2024

Viewed by 617

Abstract

In robotic manipulation, achieving efficient and reliable grasping in cluttered environments remains a significant challenge. This study presents a novel approach that integrates pushing and grasping actions using deep reinforcement learning. The proposed model employs two fully convolutional neural networks—Push-Net and Grasp-Net—that predict [...] Read more.

In robotic manipulation, achieving efficient and reliable grasping in cluttered environments remains a significant challenge. This study presents a novel approach that integrates pushing and grasping actions using deep reinforcement learning. The proposed model employs two fully convolutional neural networks—Push-Net and Grasp-Net—that predict pixel-wise Q-values for potential pushing and grasping actions from heightmap images of the scene. The training process utilizes deep Q-learning with a reward structure that incentivizes both successful pushes and grasps, encouraging the robot to create favorable conditions for grasping through strategic pushing actions. Simulation results demonstrate that the proposed model significantly outperforms traditional grasp-only policies, achieving an 87% grasp success rate in cluttered environments, compared to 60% for grasp-only approaches. The model shows robust performance in various challenging scenarios, including well-ordered configurations and novel objects, with completion rates of up to 100% and grasp success rates as high as 95.8%. These findings highlight the model’s ability to generalize to unseen objects and configurations, making it a practical solution for real-world robotic manipulation tasks. Full article

(This article belongs to the Section Actuators for Robotics)

► Show Figures

Figure 1

19 pages, 8901 KiB

Open AccessArticle

Design of a Suspension Controller with an Adaptive Feedforward Algorithm for Ride Comfort Enhancement and Motion Sickness Mitigation

by Jinwoo Kim and Seongjin Yim

Actuators 2024, 13(8), 315; https://doi.org/10.3390/act13080315 - 20 Aug 2024

Viewed by 368

Abstract

This paper presents a design method of a suspension controller with an adaptive feedforward algorithm for ride comfort enhancement and motion sickness mitigation. Recently, it was shown that motion sickness is caused by combined heave and pitch motions of a sprung mass within [...] Read more.

This paper presents a design method of a suspension controller with an adaptive feedforward algorithm for ride comfort enhancement and motion sickness mitigation. Recently, it was shown that motion sickness is caused by combined heave and pitch motions of a sprung mass within the range of 0.8 and 8 Hz. For this reason, it is necessary to design a suspension controller for the purpose of reducing the heave and pitch vibration of a sprung mass within this range. To represent the heave acceleration and the pitch rate of a sprung mass, a 4-DOF half-car model is adopted as a vehicle model. For easy implementation in a real vehicle, a static output feedback control is adopted instead of a full-state one. To reduce the heave acceleration of a sprung mass for ride comfort enhancement, a linear quadratic SOF controller is designed. To reduce the pitch rate of a sprung mass for motion sickness mitigation, a filtered-X LMS algorithm is applied. To validate the method, simulation on vehicle simulation software is conducted. From the simulation results, it is shown that the proposed method is effective for ride comfort enhancement and motion sickness mitigation. Full article

(This article belongs to the Special Issue Modeling and Control for Chassis Devices in Electric Vehicles)

► Show Figures

Figure 1

16 pages, 2459 KiB

Open AccessArticle

A Data-Driven Comprehensive Evaluation Method for Electromagnetic Suspension Maglev Control System

by Xingyu Zhou, Shi Liang, Xiaolong Li, Zhiqiang Long and Zhiqiang Wang

Actuators 2024, 13(8), 314; https://doi.org/10.3390/act13080314 - 20 Aug 2024

Viewed by 665

Abstract

As new advanced vehicles, the safety and stability of electromagnetic suspension maglev trains have always been a subject of concern. This study introduces the improved R index and τ-distance index into the performance evaluation of the suspension control system, respectively assessing the stability [...] Read more.

As new advanced vehicles, the safety and stability of electromagnetic suspension maglev trains have always been a subject of concern. This study introduces the improved R index and τ-distance index into the performance evaluation of the suspension control system, respectively assessing the stability of the suspension gap and the smoothness of train operation, combining them with grey relational analysis to achieve data-driven comprehensive evaluation. Furthermore, feasibility tests on the Fenghuang Maglev Express validate the effectiveness and superiority of the comprehensive evaluation method based on measured data. Experimental results demonstrate that the data-driven comprehensive evaluation method, through designing specialized evaluation metrics and increasing assessment dimensions, effectively evaluates the performance of the suspension system control loop. Compared to a traditional error integral comprehensive performance index, it offers greater comprehensiveness and accuracy, along with real-time state-monitoring capabilities. Full article

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

► Show Figures

Figure 1

17 pages, 10480 KiB

Open AccessArticle

Research on Vibration Control Regarding Mechanical Coupling for Maglev Trains with Experimental Verification

by Shi Liang, Chunhui Dai and Zhiqiang Long

Actuators 2024, 13(8), 313; https://doi.org/10.3390/act13080313 - 16 Aug 2024

Cited by 1 | Viewed by 459

Abstract

The electromagnet module, as a fundamental component providing levitation force for maglev trains, plays a crucial role in ensuring the stability of train operation. However, vibrations can easily occur due to the mechanical coupling between the two suspension points of the electromagnet module. [...] Read more.

The electromagnet module, as a fundamental component providing levitation force for maglev trains, plays a crucial role in ensuring the stability of train operation. However, vibrations can easily occur due to the mechanical coupling between the two suspension points of the electromagnet module. To reveal the inherent instability of the system and the coupling relationship between the state variables, a state-space equation that considers the mechanical coupling between the two suspension points is established. Furthermore, a differential control algorithm based on geometric feature transformation is proposed to mitigate the structural coupling vibration. Simulation experiments are conducted to compare the dynamic characteristics of the system before and after implementing the improvement algorithm under complex conditions. At the same time, the influence of control parameters on electromagnetic vibration was analyzed, focusing particularly on vibrations resulting from parameter mismatch, offering crucial insights for enhancing system stability. Additionally, suspension tests are carried out on the high-speed double bogie test platform in the Key Laboratory of Hunan Province to further validate the effectiveness of the proposed algorithm. The proposed control framework is both effective and concise, making it easy to implement in engineering applications. This research holds significant practical value in improving the stability of maglev trains. Full article

(This article belongs to the Special Issue Advances in High-Precision Magnetic Levitation Actuators)

► Show Figures

Figure 1

21 pages, 2415 KiB

Open AccessReview

The Challenges of Piezoelectric Actuators and Motors Application in a Space Environment

by Laurynas Šišovas, Andrius Čeponis and Sergejus Borodinas

Actuators 2024, 13(8), 312; https://doi.org/10.3390/act13080312 - 14 Aug 2024

Viewed by 862

Abstract

Piezoelectric actuators and motors are increasingly essential for space applications due to their precision, compactness, and efficiency. This review explores their advantages over traditional actuators, emphasizing their minimal electromagnetic interference, high responsiveness, and operational reliability in harsh space environments. This study highlights the [...] Read more.

Piezoelectric actuators and motors are increasingly essential for space applications due to their precision, compactness, and efficiency. This review explores their advantages over traditional actuators, emphasizing their minimal electromagnetic interference, high responsiveness, and operational reliability in harsh space environments. This study highlights the challenges posed by space conditions such as vacuum, microgravity, extreme temperatures, and radiation, which require robust design and material considerations. A comprehensive review of missions using piezo actuators, including their operating principles, material advancements, and innovative designs tailored for space conditions. In addition, numerical calculations were performed by COMSOL Multiphysics 5.6 software with the aim of analyzing the impact of temperature variations typical of the low Earth orbit (LEO) on the electromechanical properties of the piezoelectric transducer. The results indicate significant variations in the characteristics of the resonant frequency, impedance, and phase frequency in a temperature range from −20 °C to 40 °C, emphasizing the importance of accounting for thermal effects in the design. The calculations show that advantages which are proposed by piezoelectric motion systems must be combined with adaptability to harsh environmental conditions and call for further research to enhance their robustness and performance for broader application in future space missions. Full article

(This article belongs to the Special Issue Actuators in 2024)

► Show Figures

Figure 1

13 pages, 7557 KiB

Open AccessArticle

Modeling and Control of a Road Wheel Actuation Module in Steer-by-Wire System

by Insu Chung, Jungdai Choi and Kanghyun Nam

Actuators 2024, 13(8), 311; https://doi.org/10.3390/act13080311 - 14 Aug 2024

Viewed by 565

Abstract

Since the steer-by-wire system removes the mechanical connection and uses electrical signals to drive the system, it has the disadvantage of being less stable in the failure of parts or systems. Therefore, in this paper, we present a methodology for developing a digital [...] Read more.

Since the steer-by-wire system removes the mechanical connection and uses electrical signals to drive the system, it has the disadvantage of being less stable in the failure of parts or systems. Therefore, in this paper, we present a methodology for developing a digital model of the road wheel actuator of the steer-by-wire system. First, the detailed dynamics of the road wheel actuator are analyzed and simplified, and the friction model is estimated and compensated to obtain the equilibrium inertia and damping coefficient of the motor and the road wheel actuator. And to verify the accuracy of the digital model developed based on these parameters, the outputs are compared by giving the same inputs under open-loop control. Furthermore, to solve the problem caused by nonlinear disturbance and model uncertainty, a disturbance observer-based position controller is proposed. The validity of the proposed controller and the validity of the digital model development methodology are confirmed by the results of the position control experiment. Full article

(This article belongs to the Special Issue Modeling and Control for Chassis Devices in Electric Vehicles)

► Show Figures

Figure 1

18 pages, 5657 KiB

Open AccessArticle

Research on Path Planning Technology of a Line Scanning Measurement Robot Based on the CAD Model

by Huakun Jia, Haohan Chen, Chen Chen, Yichen Huang, Yang Lu, Rongke Gao and Liandong Yu

Actuators 2024, 13(8), 310; https://doi.org/10.3390/act13080310 - 11 Aug 2024

Viewed by 823

Abstract

With the development of robotics and vision measurement technology, the use of robots with line laser scanners for 3D scanning and measurement of parts has become a mainstream trend in the field of industrial inspection. Traditional scanning and measuring robots mainly use the [...] Read more.

With the development of robotics and vision measurement technology, the use of robots with line laser scanners for 3D scanning and measurement of parts has become a mainstream trend in the field of industrial inspection. Traditional scanning and measuring robots mainly use the teach-in scanning method, which has unstable scanning quality and low scanning efficiency. In this paper, the adaptive sampling method for a free-form surface, which can realize the adaptive distribution of surface measurement points according to the curvature features of free-form surfaces, is proposed first. Then, integrated with the proposed adaptive sampling method, the automatic path planning method is proposed. This method consists of adaptive sampling, scanning attitude calculation based on a quaternion, scanning viewpoint planning based on viewable cones, and scan path generation based on bi-directional scanning. Based on the proposed automatic path planning method, the scanning and measuring robot can obtain complete 3D information of the surface to be measured with high measurement accuracy and efficiency. The performance index of the laser scanner can be fully reached. Full article

(This article belongs to the Section Control Systems)

► Show Figures

Figure 1

33 pages, 13377 KiB

Open AccessArticle

Research on Output Characteristics of a Non-Contact Piezoelectric Actuator’s Micro-Displacement Amplifying Mechanism

by Huaiyong Li, Dongya Zhang, Yusheng Lin, Zhong Chen, Zhiwei Shi, Chong Li and Liang Zhao

Actuators 2024, 13(8), 309; https://doi.org/10.3390/act13080309 - 10 Aug 2024

Viewed by 622

Abstract

A non-contact piezoelectric actuator is proposed. The non-contact power transfer between stator and rotor is realized by pneumatic transmission, characterized by fast response, long life, compact structure, and easy miniaturization and control. The structure of the non-contact piezoelectric actuator is designed and its [...] Read more.

A non-contact piezoelectric actuator is proposed. The non-contact power transfer between stator and rotor is realized by pneumatic transmission, characterized by fast response, long life, compact structure, and easy miniaturization and control. The structure of the non-contact piezoelectric actuator is designed and its working principle is elucidated. The equation of the relationship between the output displacements of the non-contact piezoelectric actuator’s micro-displacement amplifying mechanism and the input displacements of piezoelectric stack is deduced, and the simulation analysis method of output displacement of the micro-displacement amplifying mechanism is established. Using the equation and the simulation analysis, the output characteristics of micro-displacement amplifying mechanism for the non-contact piezoelectric actuator and their changes along with the system parameters are investigated. The detailed process of optimal design of the micro-displacement amplifying mechanism is given by means of mathematical statistics. The prototype is made and the performance test is carried out. The correctness of the theoretical calculation and simulation analysis is verified by comparing the experimental values with the theoretical and simulated values of the output displacement of the micro-displacement amplifying mechanism. The results show that the initial angle of bridge structure I has an obvious effect on the output characteristics of the micro-displacement amplifying mechanism in the range of 5°–15°. When the lever’s rod length is 13 mm–15 mm, the bridge structure II’s rod length is 6 mm–7 mm, and the power arm length of bridge structure I’s driving lever is 5 mm–7 mm, the bridge structure II’s rod horizontal projection length is 5 mm–6 mm and the output displacement of the micro-displacement amplifying mechanism is larger. Through the optimal design, it is obtained that the bridge structure I’s initial angle is 8°, the lever’s rod length is 15 mm, the bridge structure II’s rod length is 7 mm, and the power arm length of bridge structure I driving lever is 5 mm, the bridge structure II’s rod horizontal projection length is 6 mm, and the simulated output displacement of the micro-displacement amplifying mechanism is 0.1415 mm. The prototype test reveals that as the input excitation displacement decreases, the error increases, while as the input excitation displacement increases, the error decreases. Specifically, when the input excitation displacement is 0.005 mm, the measured output displacement of the micro-displacement amplifying mechanism is 0.1239 mm, resulting in a 19.8% deviation from the theoretical value and a 12.44% deviation from the simulated value. The research work in this paper enriches the research achievements of non-contact piezoelectric actuators, and also provides a reference for designing small structure and large travel micro-displacement amplifying mechanisms of this type of actuator. Full article

(This article belongs to the Special Issue Piezoelectric Actuators in MEMS)

► Show Figures

Figure 1

17 pages, 7216 KiB

Open AccessArticle

A Double-Rotating Ferrofluid Vane Micropump with an Embedded Fixed Magnet

by Ye Wang, Zhenggui Li, Decai Li, Fang Chen, Qin Zhao, Jie Qing, Xin Li, Chao Yang, Xinyue He and Yi Zhao

Actuators 2024, 13(8), 308; https://doi.org/10.3390/act13080308 - 9 Aug 2024

Viewed by 696

Abstract

This paper introduces the prototype design, magnetic field analysis and experimental test of a double-rotating ferrofluid vane micropump with an embedded fixed magnet. The micropump is based on the working principle of a positive-displacement pump, as well as the magnetic characteristics and flow [...] Read more.

This paper introduces the prototype design, magnetic field analysis and experimental test of a double-rotating ferrofluid vane micropump with an embedded fixed magnet. The micropump is based on the working principle of a positive-displacement pump, as well as the magnetic characteristics and flow properties of magnetic fluid. Through the numerical analysis of the pump cavity magnetic field and the experimental test, the structural parameters of the micropump are optimized reasonably. The pumping flow and pumping height of the micropump were characterized at different driving speeds. The maximum pumping flow rate is approximately 410 μL/min, and the maximum pumping height is approximately 111.4 mm water column. The micropump retains the advantages of simple structure, easy manufacture, flexible control, self-sealing, self-lubrication, low heat production, etc., and can block the pumped liquid backflow. The resulting double-rotating ferrofluid blades can improve pumping efficiency and pumping capacity, and can improve pumping reliability and stability to a certain extent. Full article

(This article belongs to the Section Miniaturized and Micro Actuators)

► Show Figures

Figure 1

18 pages, 5783 KiB

Open AccessArticle

A Robust Hꝏ-Based State Feedback Control of Permanent Magnet Synchronous Motor Drives Using Adaptive Fuzzy Sliding Mode Observers

by Hamed Tahami, Sajad Saberi, Bashar Mahmood Ali, Sabah AbdulAmeer, Abbas Hameed Abdul Hussein and Hicham Chaoui

Actuators 2024, 13(8), 307; https://doi.org/10.3390/act13080307 - 9 Aug 2024

Cited by 1 | Viewed by 713

Abstract

In several applications, the accuracy and robust performance of the control method for the speed of permanent magnet synchronous motors (PMSMs) is critical. Model uncertainties, caused by inaccurate model identification, decrease the accuracy of PMSM control. To solve this problem, this paper presents [...] Read more.

In several applications, the accuracy and robust performance of the control method for the speed of permanent magnet synchronous motors (PMSMs) is critical. Model uncertainties, caused by inaccurate model identification, decrease the accuracy of PMSM control. To solve this problem, this paper presents a super robust control structure for the speed control of PMSMs. In the proposed method, the model uncertainties with Lipschitz condition together with disturbances are considered during the PMSM modeling, and their effects are handled using a robust state feedback control. To be more specific, the Lyapunov stability proof is performed in such a way that the model uncertainty effects are eliminated. Before that, the Lyapunov stability criteria have been selected in such a way that the Hꝏ conditions are considered and guaranteed. This issue helps to eliminate the effects of the disturbances. In addition, this paper considers another option to make the whole control structure robust against sudden load changes. To solve this problem, a fuzzy adaptive sliding mode observer (FASMO) is presented to determine the load torque and use it in the control signal generation. In this observer, the switched gain of the sliding mode observer (SMO) is adapted using a fuzzy system to eliminate the chattering phenomena and increase the estimation accuracy. In fact, the proposed method is called super robust because it resists model uncertainties, disturbances, and sudden load changes during three stages by robust state feedback control, Hꝏ criterion, and load estimator, respectively. The performance of the proposed approach is validated through a set of laboratory tests, and its superiority is shown compared to other methods. Full article

(This article belongs to the Special Issue Intelligent and Precision Control for Mechatronic/Electro-Hydraulic Systems)

► Show Figures

Figure 1

20 pages, 1261 KiB

Open AccessArticle

Global Stabilization of Control Systems with Input Saturation and Multiple Input Delays

by Jiawei Wu, Bing Li, Jiashuai Li, Mingze Li and Binyu Yang

Actuators 2024, 13(8), 306; https://doi.org/10.3390/act13080306 - 9 Aug 2024

Viewed by 640

Abstract

In this paper, the global stabilization problem of control systems with input saturation and multiple input delays is studied, and a new method is proposed to design nonlinear stabilization control laws. First, based on Luenberger’s canonical decomposition, the multiple-input delay system is transformed [...] Read more.

In this paper, the global stabilization problem of control systems with input saturation and multiple input delays is studied, and a new method is proposed to design nonlinear stabilization control laws. First, based on Luenberger’s canonical decomposition, the multiple-input delay system is transformed into a series of linear time-delay systems with single inputs and input saturation. However, for the converted system, each subsystem is coupled to the others. Therefore, the idea of recursion is adopted to construct a special state transformation with time delay for each subsystem and convert it into a linear system with time delay for both state variables and input variables. For the conversion system, a nonlinear controller with cascade saturation control is designed, and the controller includes some free parameters. The control performance of the controller is improved by adjusting the free parameters online. At the same time, a less conservative stability condition is established to ensure the dynamic performance of the closed-loop system. Finally, the effectiveness and superiority of the proposed method are verified by numerical simulation and practical applications in a spacecraft rendezvous system. Full article

(This article belongs to the Section Control Systems)

► Show Figures

Figure 1

14 pages, 1877 KiB

Open AccessArticle

Fast UOIS: Unseen Object Instance Segmentation with Adaptive Clustering for Industrial Robotic Grasping

by Kui Fu, Xuanju Dang, Qingyu Zhang and Jiansheng Peng

Actuators 2024, 13(8), 305; https://doi.org/10.3390/act13080305 - 9 Aug 2024

Viewed by 874

Abstract

Segmenting unseen object instances in unstructured environments is an important skill for robots to perform grasping-related tasks, where the trade-off between efficiency and accuracy is an urgent challenge to be solved. In this work, we propose a fast unseen object instance segmentation (Fast [...] Read more.

Segmenting unseen object instances in unstructured environments is an important skill for robots to perform grasping-related tasks, where the trade-off between efficiency and accuracy is an urgent challenge to be solved. In this work, we propose a fast unseen object instance segmentation (Fast UOIS) method that utilizes predicted center offsets of objects to compute the positions of local maxima and minima, which are then used for selecting initial seed points required by the mean-shift clustering algorithm. This clustering algorithm that adaptively generates seed points can quickly and accurately obtain instance masks of unseen objects. Accordingly, Fast UOIS first generates pixel-wise predictions of object classes and center offsets from synthetic depth images. Then, these predictions are used by the clustering algorithm to calculate initial seed points and to find possible object instances. Finally, the depth information corresponding to the filtered instance masks is fed into the grasp generation network to generate grasp poses. Benchmark experiments show that our method can be well transferred to the real world and can quickly generate sharp and accurate instance masks. Furthermore, we demonstrate that our method is capable of segmenting instance masks of unseen objects for robotic grasping. Full article

(This article belongs to the Special Issue Advancement in the Design and Control of Robotic Grippers)

► Show Figures

Figure 1

15 pages, 2748 KiB

Open AccessArticle

A New Variable-Stiffness Body Weight Support System Driven by Two Active Closed-Loop Controlled Drives

by Xiao Li, Jizheng Zhong, Songyang An and Yizhe Huang

Actuators 2024, 13(8), 304; https://doi.org/10.3390/act13080304 - 8 Aug 2024

Viewed by 698

Abstract

Body weight support (BWS) systems are crucial in gait rehabilitation for individuals incapacitated due to injuries or medical conditions. Traditional BWS systems typically employ either static mass–rope or dynamic mass–spring–damper configurations, which can result in inadequate support stiffness, thereby leading to compromised gait [...] Read more.

Body weight support (BWS) systems are crucial in gait rehabilitation for individuals incapacitated due to injuries or medical conditions. Traditional BWS systems typically employ either static mass–rope or dynamic mass–spring–damper configurations, which can result in inadequate support stiffness, thereby leading to compromised gait training. Additionally, these systems often lack the flexibility for easy customization of stiffness, which is vital for personalized rehabilitation treatments. A novel BWS system with online variable stiffness is introduced in this study. This system incorporates a drive mechanism governed by admittance control that dynamically adjusts the stiffness by modulating the tension of a rope wrapped around a drum. An automated control algorithm is integrated to manage a smart anti-gravity dynamic suspension system, which ensures consistent and precise weight unloading adjustments throughout rehabilitation sessions. Walking experiments were performed to evaluate the displacement and load variations within the suspension ropes, thereby validating the variable-stiffness capability of the system. The findings suggest that the online variable-stiffness BWS system can reliably alter the stiffness levels and that it exhibits robust performance, significantly enhancing the effectiveness of gait rehabilitation. The newly developed BWS system represents a significant advancement in personalized gait rehabilitation, offering real-time stiffness adjustments and ongoing weight support customization. It ensures dependable control and robust operation, marking a significant step forward in tailored therapeutic interventions for gait rehabilitation. Full article

(This article belongs to the Special Issue Actuators and Robotic Devices for Rehabilitation and Assistance)

► Show Figures

Figure 1

27 pages, 9805 KiB

Open AccessArticle

Optimization Design of a Polyimide High-Pressure Mixer Based on SSA-CNN-LSTM-WOA

by Guo Yang, Guangzhong Hu, Xianguo Tuo, Yuedong Li and Jing Lu

Actuators 2024, 13(8), 303; https://doi.org/10.3390/act13080303 - 8 Aug 2024

Viewed by 672

Abstract

Foam mixers are classified as low-pressure and high-pressure types. Low-pressure mixers rely on agitator rotation, facing cleaning challenges and complex designs. High-pressure mixers are simple and require no cleaning but struggle with uneven mixing for high-viscosity substances. Traditionally, increasing the working pressure resolved [...] Read more.

Foam mixers are classified as low-pressure and high-pressure types. Low-pressure mixers rely on agitator rotation, facing cleaning challenges and complex designs. High-pressure mixers are simple and require no cleaning but struggle with uneven mixing for high-viscosity substances. Traditionally, increasing the working pressure resolved this, but material quality limits it at higher pressures. To address the issues faced by high-pressure mixers when handling high-viscosity materials and to further improve the mixing performance of the mixer, this study focuses on a polyimide high-pressure mixer, identifying four design variables: impingement angle, inlet and outlet diameters, and impingement pressure. Using a Full Factorial Design of Experiments (DOE), the study investigates the impacts of these variables on mixing unevenness. Sample points were generated using Optimal Latin Hypercube Sampling—OLH. Combining the Sparrow Search Algorithm (SSA), Convolutional Neural Network (CNN), and Long Short-Term Memory Network (LSTM), the SSA-CNN-LSTM model was constructed for predictive analysis. The Whale Optimization Algorithm (WOA) optimized the model, to find an optimal design variable combination. The Computational Fluid Dynamics (CFD) simulation results indicate a 70% reduction in mixing unevenness through algorithmic optimization, significantly improving the mixer’s performance. Full article

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

► Show Figures

Figure 1

24 pages, 10132 KiB

Open AccessArticle

Optimization Design of Magnetically Suspended Control and Sensitive Gyroscope Deflection Channel Controller Based on Neural Network Inverse System

by Feiyu Chen, Weijie Wang, Chunmiao Yu, Shengjun Wang and Weian Zhang

Actuators 2024, 13(8), 302; https://doi.org/10.3390/act13080302 - 7 Aug 2024

Viewed by 646

Abstract

To meet the strong coupling characteristics of the MSCSG deflection channel and the demand for high control accuracy, a two-degree-of-freedom deflection channel model is firstly established for the structure and working principle of the MSCSG; to meet the strong coupling between the two [...] Read more.

To meet the strong coupling characteristics of the MSCSG deflection channel and the demand for high control accuracy, a two-degree-of-freedom deflection channel model is firstly established for the structure and working principle of the MSCSG; to meet the strong coupling between the two channels, the inverse system method is used to decouple the model; then, the operation principle of the MSCSG system is introduced, and the modeling of the power amplifier is carried out; to meet the demand for high-precision control of the MSCSG rotor system, the RBF neural network is improved using the fuzzy method to achieve high-precision estimation of the residual coupling terms and deterministic disturbances, and the adaptive sliding mode controller is designed. For the high-precision control of the MSCSG rotor system, the fuzzy method is used to improve the RBF neural network to realize the high-precision estimation of the residual coupling term and uncertain perturbation, and the adaptive sliding mode controller is designed, and the convergence of the controller is proved on the basis of the Lyapunov stability criterion. Simulation analysis shows that the method has a large improvement in decoupling performance and anti-disturbance performance compared with the traditional method, and finally, the experiment verifies the effectiveness of the present method and achieves the optimization of the deflection channel controller. The method can be extended to other magnetic levitation actuators and related fields. Full article

(This article belongs to the Special Issue Advanced Technologies on the Control Method of Electromagnetic Actuator)

► Show Figures

Figure 1

16 pages, 1062 KiB

Open AccessArticle

Model-Free Adaptive Predictive Tracking Control for High-Speed Trains Considering Quantization Effects and Denial-of-Service Attacks

by Dan Wang and Fuzhong Wang

Actuators 2024, 13(8), 301; https://doi.org/10.3390/act13080301 - 7 Aug 2024

Viewed by 603

Abstract

In this paper, the problem of model-free adaptive predictive control (MFAPC) under denial-of-service attacks and quantization effects for high-speed trains with unknown models is investigated. Since the system model of the high-speed train is unknown, the data-relational description of a high-speed train system [...] Read more.

In this paper, the problem of model-free adaptive predictive control (MFAPC) under denial-of-service attacks and quantization effects for high-speed trains with unknown models is investigated. Since the system model of the high-speed train is unknown, the data-relational description of a high-speed train system is obtained by using the dynamic linearization technique. Secondly, the challenge of periodic denial-of-service (DoS) attacks in the network channel is considered, and, assuming that the DoS attack obeys the Bernoulli distribution, a model-free adaptive predictive control scheme based on quantized signals is proposed. Then, through rigorous theoretical analyses, it is proven that the tracking error is bounded, and the final bound depends on the desired trajectory. Finally, the correctness of these theoretical analyses is verified through numerical simulation. Full article

(This article belongs to the Section Control Systems)

► Show Figures

Figure 1

15 pages, 11174 KiB

Open AccessArticle

Robustness Improved Method for Deadbeat Predictive Current Control of PMLSM with Segmented Stators

by Shijie Gu, Peng Leng, Qiang Chen, Yuxin Jin, Jie Li and Peichang Yu

Actuators 2024, 13(8), 300; https://doi.org/10.3390/act13080300 - 6 Aug 2024

Viewed by 747

Abstract

Permanent magnet linear synchronous motors (PMLSMs) with stator segmented structures are widely used in the design of high-power propulsion systems. However, due to the inherent delay and segmented structure of the systems, there are parameter disturbances in the inductance and flux linkage of [...] Read more.

Permanent magnet linear synchronous motors (PMLSMs) with stator segmented structures are widely used in the design of high-power propulsion systems. However, due to the inherent delay and segmented structure of the systems, there are parameter disturbances in the inductance and flux linkage of the motors. This makes the deadbeat predictive current control (DPCC) algorithm for a current loop less robust in the control system, leading to a decrease in control performance. Compensation methods such as compensation by observer and online estimation of parameters, are problematic to apply in practice due to the difficulty of parameter adjustment and the high complexity of the algorithm. In this paper, a robustness-improved incremental DPCC (RII-DPCC) method—which uses incremental DPCC (I-DPCC) to eliminate flux linkage parameters—is proposed. The stability of the current loop was evaluated through zero-pole analysis of the discrete transfer function. Current feedforward was introduced to improve the stability of I-DPCC. The inductance stability range of I-DPCC was increased from 0.8–1.25 times to 0–2 times the actual value, and the theoretical stability range was increased more than 4 times, effectively improving the robustness of the predictive model to flux linkage and inductance parameters. Finally, the effectiveness of the proposed method was verified through numerical simulation and experiment. Full article

(This article belongs to the Special Issue Power Electronics and Actuators)

► Show Figures

Figure 1

17 pages, 1894 KiB

Open AccessArticle

Comparative Study of Methods for Robot Control with Flexible Joints

by Ranko Zotovic-Stanisic, Rodrigo Perez-Ubeda and Angel Perles

Actuators 2024, 13(8), 299; https://doi.org/10.3390/act13080299 - 6 Aug 2024

Viewed by 711

Abstract

Robots with flexible joints are gaining importance in areas such as collaborative robots (cobots), exoskeletons, and prostheses. They are meant to directly interact with humans, and the emphasis in their construction is not on precision but rather on weight reduction and soft interaction [...] Read more.

Robots with flexible joints are gaining importance in areas such as collaborative robots (cobots), exoskeletons, and prostheses. They are meant to directly interact with humans, and the emphasis in their construction is not on precision but rather on weight reduction and soft interaction with humans. Well-known rigid robot control strategies are not valid in this area, so new control methods have been proposed to deal with the complexity introduced by elasticity. Some of these methods are seldom used and are unknown to most of the academic community. After selecting the methods, we carried out a comprehensive comparative study of algorithms: simple gravity compensation (Sgc), the singular perturbation method (Spm), the passivity-based approach (Pba), backstepping control design (Bcd), and exact gravity cancellation (Egc). We modeled these algorithms using MATLAB and simulated them for different stiffness levels. Furthermore, their practical implementation was analyzed from the perspective of the magnitudes to be measured and the computational costs of their implementation. In conclusion, the Sgc method is a fast and affordable solution if joint stiffness is relatively high. If good performance is necessary, the Pba is the best option. Full article

(This article belongs to the Special Issue Actuators in Robotic Control: Volume II)

► Show Figures

Figure 1

33 pages, 12188 KiB

Open AccessArticle

Soft Robotic System with Continuum Manipulator and Compliant Gripper: Design, Fabrication, and Implementation

by Shakir Qaddoori Fenjan and Siavash Fathollahi Dehkordi

Actuators 2024, 13(8), 298; https://doi.org/10.3390/act13080298 - 6 Aug 2024

Viewed by 1410

Abstract

This paper presents the design, construction, and implementation of a soft robotic system comprising a continuum manipulator arm equipped with a compliant gripper. Three main objectives were pursued: (1) developing a soft silicone gripper as an alternative to expensive and rigid steel grippers, [...] Read more.

This paper presents the design, construction, and implementation of a soft robotic system comprising a continuum manipulator arm equipped with a compliant gripper. Three main objectives were pursued: (1) developing a soft silicone gripper as an alternative to expensive and rigid steel grippers, enabling safe and precise handling of delicate or irregular objects such as fruits, glassware, and irregular shapes; (2) fabricating a continuum manipulator arm with robotic joints inspired by vertebrae, allowing for smooth, non-linear motion and more excellent maneuverability compared to traditional rigid arms, enabling access to hard-to-reach areas; and (3) integrating the compliant gripper with the continuum manipulator and implementing a control system for the soft gripper and remote bending arm using a microcontroller. The soft gripper, manipulator arm vertebrae, and other components were fabricated using 3D printing with PLA material for the molds. The gripper construct used hyperelastic silicone (Ecoflex 00.30). The continuum manipulator achieved a higher degree of freedom and mobility, while simulations and experiments validated the design’s effectiveness. The comparison shows that the close agreements differ by only 2.5%. In practical experiments involving lifting objects, the gripper was able to carry items with a greater mass. The proposed soft, integrated robotic system outperformed traditional rigid approaches, offering safe and flexible handling capabilities in unstructured environments. The nature-inspired design enabled a compliant grip and enhanced maneuverability, making it suitable for various applications requiring dexterous manipulation of delicate or irregularly shaped objects. Full article

(This article belongs to the Special Issue Advancement in the Design and Control of Robotic Grippers)

► Show Figures

Figure 1

24 pages, 29360 KiB

Open AccessArticle

Frequency-Dependent Bouc–Wen Modeling of Magnetorheological Damper Using Harmonic Balance Approach

by Ruijing Qian, Guoping Wang, Min Jiang, Yanni Zhang, Rongjie Zhai and Wenjie Wang

Actuators 2024, 13(8), 297; https://doi.org/10.3390/act13080297 - 6 Aug 2024

Viewed by 754

Abstract

Magnetorheological dampers (MRDs) are of great interest in engineering due to their continuously adjustable damping characteristics. Accurate models are essential for optimizing MRDs and analyzing system dynamics. However, conventional methods widely overlook the impact of excitation frequency and amplitude. To address this issue, [...] Read more.

Magnetorheological dampers (MRDs) are of great interest in engineering due to their continuously adjustable damping characteristics. Accurate models are essential for optimizing MRDs and analyzing system dynamics. However, conventional methods widely overlook the impact of excitation frequency and amplitude. To address this issue, this work proposes a modified Bouc–Wen model that can be adapted to various excitation conditions. The model’s parameters depend on the current, excitation frequency, and amplitude. The mechanical characteristics of the MRD were analyzed by the tests. The parameters in the Bouc–Wen model were identified by combining the harmonic balance method and the genetic algorithm. The modified Bouc–Wen model was established by analyzing the variation of each parameter with current, excitation frequency, and amplitude. Finally, the agreement between the modified prediction model and the test results was verified under sinusoidal excitation of 80 mm and 1 Hz. The average relative errors were 3.87%, 2.82%, 2.45%, 2.19%, and 3.27% for current excitations of 0 A, 0.5 A, 1 A, 1.5 A, and 2.0 A, respectively. Since the MRD in this paper operates from 0.5 Hz to 2 Hz, the modified model was validated in the same range. Experiments demonstrate that the modified Bouc–Wen model efficiently and accurately describes the mechanical properties of the MRD under various excitation conditions. Full article

(This article belongs to the Special Issue Magnetorheological Actuators and Dampers)

► Show Figures

Figure 1

20 pages, 2749 KiB

Open AccessArticle

A New Active Disturbance Rejection Control Tuning Method for High-Order Electro-Hydraulic Servo Systems

by Junli Zhang, Baochun Lu, Chuanjun Chen and Zhengyang Li

Actuators 2024, 13(8), 296; https://doi.org/10.3390/act13080296 - 4 Aug 2024

Viewed by 939

Abstract

In our industry, active disturbance rejection control already has been used to enhance the performance of the electro-hydraulic servo systems, despite the fact that electro-hydraulic servo systems are usually reduced to first-order and second-order systems. The aim of this paper is to extend [...] Read more.

In our industry, active disturbance rejection control already has been used to enhance the performance of the electro-hydraulic servo systems, despite the fact that electro-hydraulic servo systems are usually reduced to first-order and second-order systems. The aim of this paper is to extend the application of active disturbance rejection control to high-order electro-hydraulic servo systems by introducing a new tuning method. Active disturbance rejection control is transformed into two separate parts in the frequency domain: a pre-filter

H (s)

and a controller

T (s)

. The parameters of the pre-filter and controller can be tuned to satisfy the performance requirements of high-order electro-hydraulic servo systems using quantitative feedback theory. To assess the efficacy of the proposed tuning approach, simulations and an application of a third-order electro-hydraulic servo system have been carried out and the stability of the application with an improved active disturbance rejection controller is analyzed. The results of simulations and experiments reveal that the new tuning method for high-order electro-hydraulic servo systems can obtain a better performance than the bandwidth tuning method and other methods. Full article

(This article belongs to the Special Issue Intelligent and Precision Control for Mechatronic/Electro-Hydraulic Systems)

► Show Figures

Figure 1

10 pages, 1979 KiB

Open AccessCommunication

A Finite-Time Control Design for the Discrete-Time Chaotic Logistic Equations

by Leonardo Acho, Pablo Buenestado and Gisela Pujol

Actuators 2024, 13(8), 295; https://doi.org/10.3390/act13080295 - 4 Aug 2024

Viewed by 746

Abstract

Finite-time control theory has been widely used as a mathematical tool to design robust controllers. By manipulating the finite-time convergence proof of this theory, we developed a new control design appropriately tuned for the finite-time control of the chaotic logistics system. In this [...] Read more.

Finite-time control theory has been widely used as a mathematical tool to design robust controllers. By manipulating the finite-time convergence proof of this theory, we developed a new control design appropriately tuned for the finite-time control of the chaotic logistics system. In this experimental setup, the logistic equation is programmed into a PIC microcontroller, and a part of the controller was conceived using analog electronics. Because the system to be controlled is in the discrete-time domain, and the finite-time stability proof is stated in the continuous-time representation, our finite-time control approach is a good example for designing control algorithms in both time domain schemes. Hence, our experimental results support our main contribution. Pulse width modulation (PWM) is the format used to translate digital signals into the continuous-time field. Therefore, the main contribution of this article is the theoretical foundations for creating a recent controller that satisfies the convergence criterion in finite time and its construction using an 8-bit microcontroller. All this contributes to the chaotic logistical map. Full article

(This article belongs to the Section Control Systems)

► Show Figures

Figure 1

17 pages, 3428 KiB

Open AccessArticle

EA-CTFVS: An Environment-Agnostic Coarse-to-Fine Visual Servoing Method for Sub-Millimeter-Accurate Assembly

by Yuxuan Bai, Mingshuai Dong, Shimin Wei and Xiuli Yu

Actuators 2024, 13(8), 294; https://doi.org/10.3390/act13080294 - 3 Aug 2024

Viewed by 878

Abstract

Peg-in-hole assembly, a crucial component of robotic automation in manufacturing, continues to pose challenges due to its strict tolerance requirements. To date, most conventional peg-in-hole assembly algorithms have been validated only within simulated environments or under limited observational scenarios. In this paper, an [...] Read more.

Peg-in-hole assembly, a crucial component of robotic automation in manufacturing, continues to pose challenges due to its strict tolerance requirements. To date, most conventional peg-in-hole assembly algorithms have been validated only within simulated environments or under limited observational scenarios. In this paper, an environment-agnostic coarse-to-fine visual servoing (EA-CTFVS) assembly algorithm is proposed. Firstly, to solve the frequent issue of visual blindness during visual servoing, a bottleneck pose is proposed to be used as the desired pose for the visual servoing. Secondly, to achieve accurate assembly, a coarse-to-fine framework is constructed, in which a rough pose is given by the coarse controller to remove large initial alignment errors. For the fine controller, a twin network-based fine controller is provided to improve assembly accuracy. Furthermore, EA-CTFVS utilizes the Oriented Bounding Box (OBB) of objects as the input for visual servoing, which guarantees the system’s ability to operate effectively in diverse and complex scenes. The proposed EA-CTFVS achieves a successful assembly rate of 0.92/0.89 for initial alignment errors of 15/30 cm and 0.6 mm tolerance in real-world D-sub plug assembly tasks under complex scenarios. Full article

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

► Show Figures

Figure 1

18 pages, 7944 KiB

Open AccessArticle

Structural Optimization of a Giant Magnetostrictive Actuator Based on BP-NSGA-II Algorithm

by Yang Liu, Jianjun Meng and Tailong Li

Actuators 2024, 13(8), 293; https://doi.org/10.3390/act13080293 - 3 Aug 2024

Viewed by 783

Abstract

This study introduces an integrated structural optimization design method based on a BP neural network and NSGA-II multi-objective genetic algorithm. Initially, a two-dimensional axisymmetric finite element model of the Giant Magnetostrictive Actuator (GMA) was established, and the coupling simulation of the electromagnetic field, [...] Read more.

This study introduces an integrated structural optimization design method based on a BP neural network and NSGA-II multi-objective genetic algorithm. Initially, a two-dimensional axisymmetric finite element model of the Giant Magnetostrictive Actuator (GMA) was established, and the coupling simulation of the electromagnetic field, structural field, and temperature field was conducted to obtain the GMA’s performance parameters. Subsequently, the structural parameters of the GMA magnetic circuit, including the magnetic conducting ring, magnetic conducting sidewall, magnetic conducting body, and coil, were used as inputs, and the axial magnetic induction intensity, uniformity of axial magnetic induction intensity, and coil loss on the Giant Magnetostrictive Material (GMM) rod were used as outputs to establish a back propagation (BP) neural network model. This model delineated the nonlinear relationship between structural parameters and performance parameters. Then, the BP-NSGA-II algorithm was applied to perform multi-objective optimization on the actuator’s structural parameters, resulting in a set of Pareto optimal non-dominated solutions, from which a set of optimal solutions was obtained using the entropy weight method. Finally, simulation analysis of this optimal solution was conducted, indicating that under a 5 A power supply excitation, the maximum axial magnetic induction intensity on the optimized GMM rod increased from 0.87 T to 1.12 T; the uniformity of axial magnetic induction intensity improved from 93.1% to 96.5%; and the coil loss decreased from 7.79 × 10⁴ W/m³ to 4.97 × 10⁴ W/m³. Based on the optimization results, a prototype actuator was produced, and the test results of the prototype’s output characteristics proved the feasibility of this optimization design method. Full article

(This article belongs to the Special Issue Advanced Technologies on the Control Method of Electromagnetic Actuator)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Actuators, Volume 13, Issue 8 (August 2024) – 48 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI