Actuators

15 pages, 4798 KB

Open AccessArticle

Model Identification and Control of a Buoyancy Change Device

by João Falcão Carneiro, J. Bravo Pinto, F. Gomes de Almeida and N. A. Cruz

Actuators 2023, 12(4), 180; https://doi.org/10.3390/act12040180 - 21 Apr 2023

Cited by 6 | Viewed by 2754

There are several compelling reasons for exploring the ocean, for instance, the potential for accessing valuable resources, such as energy and minerals; establishing sovereignty; and addressing environmental issues. As a result, the scientific community has increasingly focused on the use of autonomous underwater [...] Read more.

There are several compelling reasons for exploring the ocean, for instance, the potential for accessing valuable resources, such as energy and minerals; establishing sovereignty; and addressing environmental issues. As a result, the scientific community has increasingly focused on the use of autonomous underwater vehicles (AUVs) for ocean exploration. Recent research has demonstrated that buoyancy change modules can greatly enhance the energy efficiency of these vehicles. However, the literature is scarce regarding the dynamic models of the vertical motion of buoyancy change modules. It is therefore difficult to develop adequate depth controllers, as this is a very complex task to perform in situ. The focus of this paper is to develop simplified linear models for a buoyancy change module that was previously designed by the authors. These models are experimentally identified and used to fine-tune depth controllers. Experimental results demonstrate that the controllers perform well, achieving a virtual zero steady-state error with satisfactory dynamic characteristics. Full article

(This article belongs to the Section Actuators for Robotics)

► Show Figures

Figure 1

20 pages, 4310 KB

Open AccessArticle

Learning Pose Dynamical System for Contact Tasks under Human Interaction

by Shangshang Yang, Xiao Gao, Zhao Feng and Xiaohui Xiao

Actuators 2023, 12(4), 179; https://doi.org/10.3390/act12040179 - 20 Apr 2023

Cited by 3 | Viewed by 2579

Abstract

Robots are expected to execute various operation tasks like a human by learning human working skills, especially for complex contact tasks. Increasing demands for human–robot interaction during task execution makes robot motion planning and control a considerable challenge, not only to reproduce demonstration [...] Read more.

Robots are expected to execute various operation tasks like a human by learning human working skills, especially for complex contact tasks. Increasing demands for human–robot interaction during task execution makes robot motion planning and control a considerable challenge, not only to reproduce demonstration motion and force in the contact space but also to resume working after interacting with a human without re-planning motion. In this article, we propose a novel framework based on a time-invariant dynamical system (DS), taking into account both human skills transfer and human–robot interaction. In the proposed framework, the human demonstration trajectory was modeled by the pose diffeomorphic DS to achieve online motion planning. Furthermore, the motion of the DS was modified by admittance control to satisfy different demands. We evaluated the method with a UR5e robot in the contact task of the composite woven layup. The experimental results show that our approach can effectively reproduce the trajectory and force learned from human demonstration, allow human–robot interaction safely during the task, and control the robot to return to work automatically after human interaction. Full article

(This article belongs to the Special Issue Advanced Technologies and Applications in Robotics)

► Show Figures

Figure 1

14 pages, 1929 KB

Open AccessReview

A Review of Rehabilitative and Assistive Technologies for Upper-Body Exoskeletal Devices

by Emilly Hays, Jack Slayton, Gary Tejeda-Godinez, Emily Carney, Kobe Cruz, Trevor Exley and Amir Jafari

Actuators 2023, 12(4), 178; https://doi.org/10.3390/act12040178 - 20 Apr 2023

Cited by 11 | Viewed by 6495

Abstract

This journal review article focuses on the use of assistive and rehabilitative exoskeletons as a new opportunity for individuals with diminished mobility. The article aims to identify gaps and inconsistencies in state-of-the-art assistive and rehabilitative devices, with the overall goal of promoting innovation [...] Read more.

This journal review article focuses on the use of assistive and rehabilitative exoskeletons as a new opportunity for individuals with diminished mobility. The article aims to identify gaps and inconsistencies in state-of-the-art assistive and rehabilitative devices, with the overall goal of promoting innovation and improvement in this field. The literature review explores the mechanisms, actuators, and sensing procedures employed in each application, specifically focusing on passive shoulder supports and active soft robotic actuator gloves. Passive shoulder supports are an excellent option for bearing heavy loads, as they enable the load to be evenly distributed across the shoulder joint. This, in turn, reduces stress and strain around the surrounding muscles. On the other hand, the active soft robotic actuator glove is well suited for providing support and assistance by mimicking the characteristics of human muscle. This review reveals that these devices improve the overall standard of living for those who experience various impairments but also encounter limitations requiring redress. Overall, this article serves as a valuable resource for individuals working in the field of assistive and rehabilitative exoskeletons, providing insight into the state of the art and potential areas for improvement. Full article

(This article belongs to the Special Issue Soft Robotics in Biomedical Application)

► Show Figures

Figure 1

16 pages, 32931 KB

Open AccessReview

A Review on Recent Advances in Piezoelectric Ceramic 3D Printing

by Jiwon Park, Dong-Gyu Lee, Sunghoon Hur, Jeong Min Baik, Hyun Soo Kim and Hyun-Cheol Song

Actuators 2023, 12(4), 177; https://doi.org/10.3390/act12040177 - 18 Apr 2023

Cited by 19 | Viewed by 7684

Abstract

Piezoelectric materials are a class of materials that can generate an electric charge when subjected to mechanical stress, or vice versa. These materials have a wide range of applications, from sensors and actuators to energy-harvesting devices and medical implants. Recently, there has been [...] Read more.

Piezoelectric materials are a class of materials that can generate an electric charge when subjected to mechanical stress, or vice versa. These materials have a wide range of applications, from sensors and actuators to energy-harvesting devices and medical implants. Recently, there has been growing interest in using 3D printing to fabricate piezoelectric materials with complex geometries and tailored properties. Three-dimensional printing allows for the precise control of the material’s composition, microstructure, and shape, which can significantly enhance piezoelectric materials’ performance. Three-dimensional printing has emerged as a promising technique for fabricating piezoelectric materials with tailored properties and complex geometries. The development of high-performance piezoelectric materials using 3D printing could have significant implications for various applications, including sensors, energy harvesting, and medical devices. In this review paper, 3D printing methods for piezoelectric materials, their advantages and disadvantages, representative piezoelectric ceramics, and examples of 3D printing are presented. Furthermore, the applications utilizing these materials are summarized. Full article

(This article belongs to the Special Issue Piezoelectric Actuators—A Special Issue in Honor of Prof. Dr. Kenji Uchino)

► Show Figures

Figure 1

13 pages, 3287 KB

Open AccessArticle

Adaptive Multi-Parameter Estimation of Inertial Stabilization Platform with Unknown Load

by Jieji Zheng, Xin Xie, Baoyu Li, Ziping Wan, Ning Chen and Dapeng Fan

Actuators 2023, 12(4), 176; https://doi.org/10.3390/act12040176 - 18 Apr 2023

Cited by 1 | Viewed by 2273

Abstract

In order to improve the state monitoring and adaptive control capability of inertial stabilization platforms (ISPs) with unknown loads, it is necessary to estimate the dynamic parameters comprehensively online. However, most current online estimation methods regard the system as a linear dual-inertia model [...] Read more.

In order to improve the state monitoring and adaptive control capability of inertial stabilization platforms (ISPs) with unknown loads, it is necessary to estimate the dynamic parameters comprehensively online. However, most current online estimation methods regard the system as a linear dual-inertia model which neglects the backlash and nonlinear friction torque. It reduces the accuracy of the model and leads to incomplete and low accuracy of the estimated parameters. The purpose of this research is to achieve a comprehensive and accurate online estimation of multiple parameters of ISPs and lay a foundation for state monitoring and adaptive control of ISPs. First, a dual-inertia model containing backlash and nonlinear friction torque of the motor and load is established. Then, the auto-regressive moving average (ARMA) model of the motor and load is established by the forward Euler method, which clearly expresses the online identification formula of the parameters. On this basis, the adaptive identification method based on the recursive extended least squares (RELS) algorithm is used to realize the online estimation of multiple parameters. The simulation and experimental results show that the proposed adaptive multi-parameter estimation method can realize the simultaneous online identification of the moment of inertia of the load, the damping coefficient of motor and load, the transmission stiffness, the Coulomb friction torque of motor and load, and the backlash, and the steady-state error is less than 10%. Compared with the traditional linear dual-inertia model, the similarity between the model based on the proposed adaptive parameter estimation algorithm and the actual system is increased by 65.3%. Full article

(This article belongs to the Section Control Systems)

► Show Figures

Figure 1

25 pages, 6338 KB

Open AccessArticle

Enhancing Seismic Resilience of Existing Reinforced Concrete Building Using Non-Linear Viscous Dampers: A Comparative Study

by Raja Dilawar Riaz, Umair Jalil Malik, Mati Ullah Shah, Muhammad Usman and Fawad Ahmed Najam

Actuators 2023, 12(4), 175; https://doi.org/10.3390/act12040175 - 17 Apr 2023

Cited by 18 | Viewed by 5438

Abstract

After the catastrophic destruction of the October 2005 Kashmir earthquake, the first building code of Pakistan was developed in 2007. The sole purpose of the building code of Pakistan (BCP) was to incorporate advancements in earthquake-resistant design to fortify structures and ensure the [...] Read more.

After the catastrophic destruction of the October 2005 Kashmir earthquake, the first building code of Pakistan was developed in 2007. The sole purpose of the building code of Pakistan (BCP) was to incorporate advancements in earthquake-resistant design to fortify structures and ensure the safety of citizens against future seismic events. After 2007, the BCP was not revised till 2021 to include the changes over time. However, the recently updated version of BCP 2021 highlights that the seismicity of many regions in Pakistan is high, which is not truly reflected in the BCP 2007. Therefore, the advancements in earthquake-resistant design due to the growing concerns about the potential risks of seismicity in the region have been incorporated into the updated version of the BCP. However, there are concerns among researchers that many structures designed on the 2007 code may need seismic fortification. Therefore, the current study focuses on the seismic fortification of existing systems that were developed using previous codes. Non-linear viscous fluid dampers are used to improve the seismic resilience of existing structures. This study compares the seismic performance of an existing reinforced concrete building with and without non-linear viscous dampers and subjected to a non-linear dynamic analysis. The performance of the building is evaluated in terms of story displacement, story drift, story acceleration, and energy dissipation mechanisms. Adding the non-linear fluid viscous dampers in the structure caused a decrease in the inter-story drift by around 31.16% and the roof displacement was reduced by around 36.58%. In addition to that, in a controlled structure, more than 70% of energy was dissipated by the fluid viscous dampers. These results indicate that adding the non-linear fluid viscous dampers to the existing structure significantly improved the vibration performance of the system against undesirous vibrations. The outcomes of this study also provide a very detailed insight into the usage of non-linear viscous dampers for improving the seismic performance of existing buildings and can be used to develop effective strategies to mitigate the impact of seismic events on already built structures. Full article

(This article belongs to the Special Issue Actuators and Dampers for Vibration Control: Damping and Isolation Applications - Volume II)

► Show Figures

Figure 1

16 pages, 4616 KB

Open AccessArticle

Design of a Noncontact Torsion Testing Device Using Magnetic Levitation Mechanism

by Mengyi Ren and Koichi Oka

Actuators 2023, 12(4), 174; https://doi.org/10.3390/act12040174 - 17 Apr 2023

Cited by 2 | Viewed by 2475

Abstract

To facilitate torsion testing in special environments, a noncontact torsion testing device, where a noncontact torque can be transmitted to a specimen, was developed using magnetic levitation technology. A permanent magnetic gear is used to produce noncontact torque. In addition, four electromagnets and [...] Read more.

To facilitate torsion testing in special environments, a noncontact torsion testing device, where a noncontact torque can be transmitted to a specimen, was developed using magnetic levitation technology. A permanent magnetic gear is used to produce noncontact torque. In addition, four electromagnets and four attractive-type permanent magnetic bearings were employed to realize levitation; in more detail, the four electromagnets actively stabilized two levitation degrees of freedom (DoFs), while the four attractive-type permanent magnetic bearings passively stabilized four DoFs. Furthermore, a plant model considering the effect caused by the four attractive-type permanent magnetic bearings was built for the two levitation DoFs requiring active control. Based on the plant model, two PD-controllers were designed. Moreover, a control simulation was conducted to obtain appropriate PD-gains. Finally, experiments further validated the feasibility of the whole scheme, and it was proven that the device can apply a 0.126 N·m torque to the specimen while maintaining levitation. Full article

(This article belongs to the Special Issue Magnetic Bearing Actuators II)

► Show Figures

Figure 1

14 pages, 4976 KB

Open AccessArticle

Error Analysis of a Coordinate Measuring Machine with a 6-DOF Industrial Robot Holding the Probe

by Yaowei Sun, Lei Lu, Fengzhou Wu, Songlu Xiao, Junjie Sha and Lei Zhang

Actuators 2023, 12(4), 173; https://doi.org/10.3390/act12040173 - 16 Apr 2023

Cited by 7 | Viewed by 4288

Abstract

A complex surface measurement is important for quality control and manufacturing processes. Articulated arm coordinate measuring machines (AACMMs) are widely used in measuring the complex surface. However, the AACMMs that are currently used always require manual operation, which reduces efficiency and introduces operator [...] Read more.

A complex surface measurement is important for quality control and manufacturing processes. Articulated arm coordinate measuring machines (AACMMs) are widely used in measuring the complex surface. However, the AACMMs that are currently used always require manual operation, which reduces efficiency and introduces operator errors. This study presents a measuring device with a 6−DOF industrial robot holding a contact probe, which realizes the automation measurement of a complex surface and eliminates operator errors compared with the traditional measurement process of an AACMM. In order to explore the source of the measuring errors of the device, the influence of three measurement parameters (approaching velocity, contact angle, and measurement position) on the measurement error of the device is analyzed in this paper. A calibration ball measurement experiment is conducted for each parameter. The results show that the optimal approaching velocity of the measuring device is around 2 mm/s, the probe should be as perpendicular as possible to the surface being measured during the measurement, and the maximum measurement error at different positions is 0.1979 mm, with a maximum repeatability error of 0.0219 mm. This study will help improve the automation measuring errors of the AACMM by utilizing an industrial robot to hold the probe, pushing for a wider application of the AACMM. Full article

(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)

► Show Figures

Figure 1

15 pages, 4113 KB

Open AccessArticle

A Modular Soft Gripper with Combined Pneu-Net Actuators

by Xinjie Zhang, Shouyi Yu, Jianlong Dai, Ayobami Elisha Oseyemi, Linlin Liu, Ningyu Du and Fangrui Lv

Actuators 2023, 12(4), 172; https://doi.org/10.3390/act12040172 - 13 Apr 2023

Cited by 17 | Viewed by 4704

Abstract

Soft Pneumatic-Network (Pneu-Net) Actuators (SPAs) have been used extensively in making soft grippers, due to their simple driving forms and large bending deformation. However, the capabilities of the regular SPAs in complex soft gripping application environments are alone insufficient. This work, thus, proposes [...] Read more.

Soft Pneumatic-Network (Pneu-Net) Actuators (SPAs) have been used extensively in making soft grippers, due to their simple driving forms and large bending deformation. However, the capabilities of the regular SPAs in complex soft gripping application environments are alone insufficient. This work, thus, proposes a modular soft gripper that combines the functionalities of regular and herringbone actuators. The bending deformation characteristics of the two actuators under pneumatic pressures are verified by finite element (FE) simulations and experiments. The functional characteristics of the two actuators are investigated experimentally through a series of methods including the blocking force test, lifting test, grasping strength test, and suction force test. The experimental results show that the regular actuator has the advantages of greater longitudinal bending deformation and higher blocking force; while, the herringbone actuator has better lifting stability and grasping strength due to its conformal deformations both in longitudinal and transverse directions. In addition, the vacuum experiments demonstrate that the actuators can lift heavy plate-like objects through vacuum suction. Based on the functional behaviors of the two actuators, the proposed modular gripper is loaded onto automatic equipment, and the gripper is tested to hook, grasp, or lift various objects with different shapes, sizes, and weights. In essence, the modular and multi-functional characteristics of the design make it a promising candidate for relatively complex and advanced gripping applications. Full article

(This article belongs to the Section Actuators for Robotics)

► Show Figures

Figure 1

22 pages, 4839 KB

Open AccessArticle

Predefined-Time Fault-Tolerant Trajectory Tracking Control for Autonomous Underwater Vehicles Considering Actuator Saturation

by Ye Li, Jiayu He, Qiang Zhang, Wenjun Zhang and Yanying Li

Actuators 2023, 12(4), 171; https://doi.org/10.3390/act12040171 - 12 Apr 2023

Cited by 8 | Viewed by 2563

Abstract

This paper presents the design of two predefined-time active fault-tolerant controllers for the trajectory tracking of autonomous underwater vehicles (AUVs) which can address actuator faults without causing actuator saturation. The first controller offers improved steady-state trajectory tracking precision, while the second ensures a [...] Read more.

This paper presents the design of two predefined-time active fault-tolerant controllers for the trajectory tracking of autonomous underwater vehicles (AUVs) which can address actuator faults without causing actuator saturation. The first controller offers improved steady-state trajectory tracking precision, while the second ensures a nonsingular property. Firstly, a predefined-time sliding mode controller is formulated based on a predefined-time disturbance observer by integrating a novel predefined-time auxiliary system to prevent the control input from exceeding the actuator’s physical limitations. Subsequently, a non-singular backstepping controller is introduced to circumvent potential singularities in the sliding mode controller, guaranteeing that the trajectory tracking error is uniformly ultimately bounded (UUB) within the predefined time. Additionally, theoretical analysis and simulation results are presented to illustrate the advantages of the proposed method. Full article

(This article belongs to the Section Control Systems)

► Show Figures

Figure 1

21 pages, 15510 KB

Open AccessArticle

Automatic Aluminum Alloy Surface Grinding Trajectory Planning of Industrial Robot Based on Weld Seam Recognition and Positioning

by Hong Zhao, Ke Wen, Tianjian Lei, Yinan Xiao and Yang Pan

Actuators 2023, 12(4), 170; https://doi.org/10.3390/act12040170 - 12 Apr 2023

Cited by 12 | Viewed by 4503

Abstract

In this paper, we propose a novel method for planning grinding trajectories on curved surfaces to improve the grinding efficiency of large aluminum alloy surfaces with welds and defect areas. Our method consists of three parts. Firstly, we introduce a deficiency positioning method [...] Read more.

In this paper, we propose a novel method for planning grinding trajectories on curved surfaces to improve the grinding efficiency of large aluminum alloy surfaces with welds and defect areas. Our method consists of three parts. Firstly, we introduce a deficiency positioning method based on a two-dimensional image and three-dimensional point cloud, which enables us to accurately and quickly locate the three-dimensional defective areas. Secondly, we propose a 2D weld positioning method based on the defect area and obtain the spatial position of the 3D weld by combining the relationship between 2D and 3D images. Additionally, we propose an orthogonal projection method from the point cloud to the aluminum alloy surface to calculate the weld reinforcement. Thirdly, we present a space spiral grinding trajectory planning method for complex curved surfaces based on the characteristics of the weld reinforcement, spatial position, and spatial position information of the defect area. This method shortens the grinding time of the defect area and improves efficiency. Simulation and experimental results show that our grinding trajectory planning method is more efficient than other grinding methods in removing defects from the surface of aluminum alloys. Moreover, the defect area after grinding is smoother than before. Full article

(This article belongs to the Special Issue Advanced Technologies and Applications in Robotics)

► Show Figures

Figure 1

19 pages, 4352 KB

Open AccessArticle

A Double-Layer Model Predictive Control Approach for Collision-Free Lane Tracking of On-Road Autonomous Vehicles

by Weishan Yang, Yuepeng Chen and Yixin Su

Actuators 2023, 12(4), 169; https://doi.org/10.3390/act12040169 - 11 Apr 2023

Cited by 8 | Viewed by 3363

Abstract

This paper proposes a double-layer model predictive control (MPC) algorithm for the integrated path planning and trajectory tracking of autonomous vehicles on roads. The upper module is responsible for generating collision-free lane trajectories, while the lower module is responsible for tracking this trajectory. [...] Read more.

This paper proposes a double-layer model predictive control (MPC) algorithm for the integrated path planning and trajectory tracking of autonomous vehicles on roads. The upper module is responsible for generating collision-free lane trajectories, while the lower module is responsible for tracking this trajectory. A simplified vehicle model based on the friction cone is proposed to reduce the computation time for trajectory planning in the upper layer module. To achieve dynamic and accurate collision avoidance, a polygonal distance-based dynamic obstacle avoidance method is proposed. A vertical load calculation method for the tires is introduced to design the anti-rollover constraint in the lower layer module. Numerical simulations, with static and dynamic obstacle scenarios, are conducted on the MATLAB platform and compared with two state-of-the-art MPC algorithms. The results demonstrate that the proposed algorithm outperforms the other two algorithms regarding computation time and collision avoidance efficiency. Full article

(This article belongs to the Special Issue Advanced Actuation and Control Technologies for Vehicle Driving Systems)

► Show Figures

Figure 1

22 pages, 10599 KB

Open AccessArticle

Control of an Outer Rotor Doubly Salient Permanent Magnet Generator for Fixed Pitch kW Range Wind Turbine Using Overspeed Flux Weakening Operations

by Aziz Remli, Cherif Guerroudj, Jean-Frédéric Charpentier, Tarek Kendjouh, Nicolas Bracikowski and Yannis L. Karnavas

Actuators 2023, 12(4), 168; https://doi.org/10.3390/act12040168 - 6 Apr 2023

Cited by 2 | Viewed by 2670

Abstract

This paper deals with the analysis of the dynamic performance of a generator with a doubly salient exterior rotor excited by permanent magnets inserted in the stator yoke. The electrical generator works at low speed and is devoted to a wind energy conversion [...] Read more.

This paper deals with the analysis of the dynamic performance of a generator with a doubly salient exterior rotor excited by permanent magnets inserted in the stator yoke. The electrical generator works at low speed and is devoted to a wind energy conversion system. Indeed, the studied generator is a robust high-torque machine and can be directly coupled to the turbine blades. It must therefore assure the energy conversion for wind speeds lower or higher than its base speed. In fact, the control technique used in this work covers the two main operating zones: below the base speed and above it. In the first case, the maximum torque per ampere control law is developed; however, when the base speed is reached, the flux decay control law is implemented and, consequently, the system works above the nominal conditions. Fuzzy logic controllers are employed to regulate direct and quadrature machine currents and DC voltage in order to obtain satisfactory regulation performances. The ensemble of the wind turbine and electrical machine with technical control is performed in Matlab/Simulink software. The simulation results obtained show the capability of the machine to operate at variable speeds, ensuring efficient energy conversion under and over the nominal speed. Full article

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

► Show Figures

Figure 1

27 pages, 6338 KB

Open AccessArticle

Dynamic Modeling and Attitude–Vibration Cooperative Control for a Large-Scale Flexible Spacecraft

by Guiqin He and Dengqing Cao

Actuators 2023, 12(4), 167; https://doi.org/10.3390/act12040167 - 6 Apr 2023

Cited by 14 | Viewed by 4607

Abstract

Modern spacecraft usually have larger and more flexible appendages whose vibration becomes more and more prominent, and it has a great influence on the precision of spacecraft attitude. Therefore, the cooperative control of attitude maneuvering and structural vibration of the system has become [...] Read more.

Modern spacecraft usually have larger and more flexible appendages whose vibration becomes more and more prominent, and it has a great influence on the precision of spacecraft attitude. Therefore, the cooperative control of attitude maneuvering and structural vibration of the system has become a significant issue in the spacecraft design process. We developed a low-dimensional and high-precision mathematical model for a large-scale flexible spacecraft (LSFS) equipped with a pair of hinged solar arrays in this paper. The analytic global modes are used to obtain the rigid–flexible coupling discrete dynamic model, and the governing equations with multiple DOFs for the system are derived by using the Hamiltonian principle. The rigid–flexible coupled oscillating responses of LSFS under the three-axis attitude-driving torque pulse during the in-orbit attitude maneuvering process are investigated. A study on the flexibility of the hinge was also conducted. Based on the simplified and accurate dynamic model of the system, we can obtain a state-space model for LSFS conveniently, and the cooperative control schemes for rigid motion and flexible oscillation control are designed by using the LQR, PD, and PD + IS algorithms. The simulation results show that three cooperative controllers can realize spacecraft attitude adjustment and synchronously eliminate flexible oscillation successfully. By comparison, the PD + IS controller is simpler so that it is suitable for the real-time attitude–vibration cooperative control of spacecraft. Full article

(This article belongs to the Special Issue Advanced Spacecraft Structural Dynamics and Actuation Control)

► Show Figures

Figure 1

20 pages, 9022 KB

Open AccessArticle

A Real-Time Path Planning Algorithm Based on the Markov Decision Process in a Dynamic Environment for Wheeled Mobile Robots

by Yu-Ju Chen, Bing-Gang Jhong and Mei-Yung Chen

Actuators 2023, 12(4), 166; https://doi.org/10.3390/act12040166 - 6 Apr 2023

Cited by 5 | Viewed by 4398

Abstract

A real-time path planning algorithm based on the Markov decision process (MDP) is proposed in this paper. This algorithm can be used in dynamic environments to guide the wheeled mobile robot to the goal. Two phases (the utility update phase and the policy [...] Read more.

A real-time path planning algorithm based on the Markov decision process (MDP) is proposed in this paper. This algorithm can be used in dynamic environments to guide the wheeled mobile robot to the goal. Two phases (the utility update phase and the policy update phase) constitute the path planning of the entire system. In the utility update phase, the utility value is updated based on information from the observable environment. Obstacles and walls reduce the utility value, pushing agents away from these impassable areas. The utility value of the goal is constant and is always only the largest. In the policy update, a series of policies can be obtained by the strategy of maximizing its long-term total reward, and the series will eventually form a path towards the goal, regardless of where the agent is located. The simulations and experiments show that it takes longer to find the first path in the beginning due to the large changes of utility value, but once the path is planned, it requires a small amount of time cost to respond to the environmental changes. Therefore, the proposed path planning algorithm has an advantage in dynamic environments where obstacles move in unpredictable ways. Full article

(This article belongs to the Special Issue Actuators in 2022)

► Show Figures

Figure 1

16 pages, 3747 KB

Open AccessArticle

An ADS-B Information-Based Collision Avoidance Methodology to UAV

by Liang Tong, Xusheng Gan, Yarong Wu, Nan Yang and Maolong Lv

Actuators 2023, 12(4), 165; https://doi.org/10.3390/act12040165 - 6 Apr 2023

Cited by 10 | Viewed by 3482

Abstract

A collision avoidance method that is specifically tailored for UAVs (unmanned aerial vehicles) operating in converging airspace is proposed. The method is based on ADS-B messages and it aims to detect and resolve conflicts between UAVs. The proposed method involves two main steps. [...] Read more.

A collision avoidance method that is specifically tailored for UAVs (unmanned aerial vehicles) operating in converging airspace is proposed. The method is based on ADS-B messages and it aims to detect and resolve conflicts between UAVs. The proposed method involves two main steps. First, a UAV conflict-sensing scheme is developed, which utilizes ADS-B information flow path and analyzes the message format information. Second, an unscented Kalman filter is used to predict UAV trajectories based on the acquired ADS-B information. The predicted information is then used to determine potential conflict scenarios, and different deconfliction strategies are selected accordingly. These strategies include speed regulation, direction regulation, and compound deconfliction, and are mathematically validated using the velocity obstacle method. The feasibility and effectiveness of the proposed method are evaluated through simulation, and it is concluded that the method can significantly improve the conflict resolution capability of UAV flights. This research provides a valuable contribution to the field of UAV collision avoidance, and can serve as a theoretical foundation for further advancements in this area. Full article

(This article belongs to the Special Issue Fault-Tolerant Control for Unmanned Aerial Vehicles (UAVs))

► Show Figures

Figure 1

24 pages, 2159 KB

Open AccessArticle

A Decentralized LQR Output Feedback Control for Aero-Engines

by Xiaoxiang Ji, Jianghong Li, Jiao Ren and Yafeng Wu

Actuators 2023, 12(4), 164; https://doi.org/10.3390/act12040164 - 6 Apr 2023

Cited by 3 | Viewed by 2469

Abstract

Aero-engine control systems generally adopt centralized or distributed control schemes, in which all or most of the tasks of the control system are mapped to a specific processor for processing. The performance and reliability of this processor have a significant impact on the [...] Read more.

Aero-engine control systems generally adopt centralized or distributed control schemes, in which all or most of the tasks of the control system are mapped to a specific processor for processing. The performance and reliability of this processor have a significant impact on the control system. Based on the aero-engine distributed control system (DCS), we propose a decentralized controller scheme. The characteristic of this scheme is that a network composed of a group of nodes acts as the controller of the system, so that there is no core control processor in the system, and the computation is distributed throughout the entire network. An LQR output feedback control is constructed using system input and output, and the control tasks executed on each node in the decentralized controller are obtained. The constructed LQR output feedback is equivalent to the optimal LQR state feedback. The primal-dual principle is used to tune the parameters of each decentralized controller. The parameter tuning algorithm is simple to calculate, making it conducive for engineering applications. Finally, the proposed scheme was verified by simulation. The simulation results show that a high-precision feedback gain matrix can be obtained with a maximum of eight iterations. The parameter tuning algorithm proposed in this paper converges quickly during the calculation process, and the constructed output feedback scheme achieves equivalent performance to the state feedback scheme, demonstrating the effectiveness of the design scheme proposed in this paper. Full article

(This article belongs to the Special Issue Dynamics and Control of Aerospace Systems)

► Show Figures

Figure 1

38 pages, 6821 KB

Open AccessReview

Inchworm Motors and Beyond: A Review on Cooperative Electrostatic Actuator Systems

by Almothana Albukhari and Ulrich Mescheder

Actuators 2023, 12(4), 163; https://doi.org/10.3390/act12040163 - 4 Apr 2023

Cited by 6 | Viewed by 4749

Abstract

Having benefited from technological developments, such as surface micromachining, high-aspect-ratio silicon micromachining and ongoing miniaturization in complementary metal–oxide–semiconductor (CMOS) technology, some electrostatic actuators became widely used in large-volume products today. However, due to reliability-related issues and inherent limitations, such as the pull-in instability [...] Read more.

Having benefited from technological developments, such as surface micromachining, high-aspect-ratio silicon micromachining and ongoing miniaturization in complementary metal–oxide–semiconductor (CMOS) technology, some electrostatic actuators became widely used in large-volume products today. However, due to reliability-related issues and inherent limitations, such as the pull-in instability and extremely small stroke and force, commercial electrostatic actuators are limited to basic implementations and the micro range, and thus cannot be employed in more intricate systems or scaled up to the macro range (mm stroke and N force). To overcome these limitations, cooperative electrostatic actuator systems have been researched by many groups in recent years. After defining the scope and three different levels of cooperation, this review provides an overview of examples of weak, medium and advanced cooperative architectures. As a specific class, hybrid cooperative architectures are presented, in which besides electrostatic actuation, another actuation principle is used. Inchworm motors—belonging to the advanced cooperative architectures—can provide, in principle, the link from the micro to the macro range. As a result of this outstanding potential, they are reviewed and analyzed here in more detail. However, despite promising research concepts and results, commercial applications are still missing. The acceptance of piezoelectric materials in some industrial CMOS facilities might now open the gate towards hybrid cooperative microactuators realized in high volumes in CMOS technology. Full article

(This article belongs to the Special Issue Cooperative Microactuator Devices and Systems)

► Show Figures

Figure 1

21 pages, 2643 KB

Open AccessArticle

An Optimization-Based High-Precision Flexible Online Trajectory Planner for Forklifts

by Yizhen Sun, Junyou Yang, Zihan Zhang and Yu Shu

Actuators 2023, 12(4), 162; https://doi.org/10.3390/act12040162 - 4 Apr 2023

Cited by 5 | Viewed by 3091

Abstract

There are numerous prospects for automated unmanned forklifts in the fields of intelligent logistics and intelligent factories. However, existing unmanned forklifts often operate according to offline path planning first followed by path tracking to move materials. This process does not meet the needs [...] Read more.

There are numerous prospects for automated unmanned forklifts in the fields of intelligent logistics and intelligent factories. However, existing unmanned forklifts often operate according to offline path planning first followed by path tracking to move materials. This process does not meet the needs of flexible production in intelligent logistics. To solve this problem, we proposed an optimized online motion planner based on the output of the state grid as the original path. Constraints such as vehicle kinematics; dynamics; turning restriction at the end of the path; spatial safety envelope; and the position and orientation at the starting point and the ending point were considered during path optimization, generating a precise and smooth trajectory for industrial forklifts that satisfied non-holonomic vehicle constraints. In addition, a new rapid algorithm for calculating the spatial safety envelope was proposed in this article, which can be used for collision avoidance and as a turning-angle constraint term for path smoothing. Finally, a simulation experiment and real-world tray-insertion task experiment were carried out. The experiments showed that the proposal was effective and accurate via online motion planning and the tracking of automated unmanned forklifts in a complicated environment and that the proposal fully satisfied the needs of industrial navigation accuracy. Full article

(This article belongs to the Topic Advances in Mobile Robotics Navigation)

► Show Figures

Figure 1

11 pages, 1408 KB

Open AccessCommunication

Non-Reciprocal MEMS Periodic Structure

by Jacopo Marconi, Davide Enrico Quadrelli and Francesco Braghin

Actuators 2023, 12(4), 161; https://doi.org/10.3390/act12040161 - 4 Apr 2023

Cited by 5 | Viewed by 2148

Abstract

In recent years, active periodic structures with in-time modulated parameters have drawn ever-increasing attention due to their peculiar (and sometimes exotic) wave propagation properties. Although many experimental works have shown the efficacy of time-modulation strategies, the benchmarks proposed until now have been mostly [...] Read more.

In recent years, active periodic structures with in-time modulated parameters have drawn ever-increasing attention due to their peculiar (and sometimes exotic) wave propagation properties. Although many experimental works have shown the efficacy of time-modulation strategies, the benchmarks proposed until now have been mostly proof-of-concept demonstrators, with little attention to the feasibility of the solution for practical purposes. In this work, we propose a micro electro-mechanical system (MEMS) periodic structure with modulated electromechanical stiffness featuring non-reciprocal band-gaps that are frequency bands where elastic waves are allowed to travel only in one direction. To this aim, we derive a simplified analytical lumped-parameter model, which is then verified through numerical simulations of both the lumped-parameter system and the high-fidelity multiphysics finite element model including electrostatic effects. We envision that this system, which can easily be manufactured through standard MEMS production processes, may be used as a directional filter in MEMS devices such as insulators and circulators. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Nonlinear Control and Dynamics for MEMS)

► Show Figures

Figure 1

17 pages, 18565 KB

Open AccessEditor’s ChoiceArticle

Tendon-Driven Gripper with Variable Stiffness Joint and Water-Cooled SMA Springs

by Phuoc Thien Do, Quang Ngoc Le, Quoc Viet Luong, Hyun-Ho Kim, Hyeong-Mo Park and Yeong-Jin Kim

Actuators 2023, 12(4), 160; https://doi.org/10.3390/act12040160 - 4 Apr 2023

Cited by 22 | Viewed by 9148

Abstract

In recent years, there has been an increase in the development of medical robots to enhance interventional MRI-guided therapies and operations. Magnetic resonance imaging (MRI) surgical robots are particularly attractive due to their ability to provide excellent soft-tissue contrast during these procedures. This [...] Read more.

In recent years, there has been an increase in the development of medical robots to enhance interventional MRI-guided therapies and operations. Magnetic resonance imaging (MRI) surgical robots are particularly attractive due to their ability to provide excellent soft-tissue contrast during these procedures. This paper describes a novel design for a tendon-driven gripper that utilizes four shape memory alloy (SMA) spring actuators and variable stiffness joints controlled by SMA coils for use in MRI surgical robot applications. The contact force of the gripper link is determined by the mechanical properties of the SMA spring actuators (SSA) and the angle of each linkage, and the joint stiffness can be adjusted by varying the electrical current applied to the SMA coil. To enhance the efficiency of the SSAs, a new cooling system using water has been proposed and implemented. To validate the effectiveness of our proposed gripper, we conducted three types of experiments, namely, a single SSA experiment, a single SMA coil experiment, and a whole gripper experiment. The experimental results demonstrate that the proposed water-cooling system can effectively solve temperature issues of SMA, and the joint stiffness in the austenite state is higher than that in the martensite state. Moreover, our experiments show that the presented gripper is capable of grasping and holding objects of various shapes and weights. Full article

(This article belongs to the Section Actuators for Robotics)

► Show Figures

Figure 1

21 pages, 18791 KB

Open AccessArticle

Hoist-Based Shape Memory Alloy Actuator with Multiple Wires for High-Displacement Applications

by Carmen Ballester, Dorin Copaci, Janeth Arias, Luis Moreno and Dolores Blanco

Actuators 2023, 12(4), 159; https://doi.org/10.3390/act12040159 - 4 Apr 2023

Cited by 6 | Viewed by 3500

Abstract

Shape memory alloys (SMAs) are smart materials that change their crystalline structures when subjected to heat or tension, resulting in a macroscopic deformation. When applied to actuators, SMAs present a remarkable load–weight ratio and flexibility, making them suitable for diverse applications. However, challenges [...] Read more.

Shape memory alloys (SMAs) are smart materials that change their crystalline structures when subjected to heat or tension, resulting in a macroscopic deformation. When applied to actuators, SMAs present a remarkable load–weight ratio and flexibility, making them suitable for diverse applications. However, challenges such as their energy consumption, nonlinear control, and low displacement must be considered. This paper presents a new strategy for improving the total displacement while adding neither supplementary SMA wires nor complex external devices. In addition, a novel control strategy is proposed to improve the nonlinearity of SMAs’ behavior. A hoist system was developed to linearly increase the displacement with the number of pulleys and wire turns used. The design also used parallel actuation to increase the load capacity. The actuator presented a high load capacity with reduced weight, lifting more than 100 times its own mass, with a low-cost and robust external system. The simplicity of the actuator’s control and production and its lightness make it a suitable option for a wide range of applications, including wearable exoskeletons. Full article

(This article belongs to the Section Actuators for Robotics)

► Show Figures

Figure 1

23 pages, 10563 KB

Open AccessArticle

Multi-Head Attention Network with Adaptive Feature Selection for RUL Predictions of Gradually Degrading Equipment

by Lei Nie, Shiyi Xu and Lvfan Zhang

Actuators 2023, 12(4), 158; https://doi.org/10.3390/act12040158 - 3 Apr 2023

Cited by 6 | Viewed by 3363

Abstract

A multi-head-attention-network-based method is proposed for effective information extraction from multidimensional data to accurately predict the remaining useful life (RUL) of gradually degrading equipment. The multidimensional features of the desired equipment were evaluated using a comprehensive evaluation index, constructed of discrete coefficients, based [...] Read more.

A multi-head-attention-network-based method is proposed for effective information extraction from multidimensional data to accurately predict the remaining useful life (RUL) of gradually degrading equipment. The multidimensional features of the desired equipment were evaluated using a comprehensive evaluation index, constructed of discrete coefficients, based on correlation, monotonicity, and robustness. For information extraction, the optimal feature subset, determined by the adaptive feature selection method, was input into the multi-head temporal convolution network–bidirectional long short-term memory (TCN-BILSTM) network. Each feature was individually mined to avoid the loss of information. The effectiveness of our proposed RUL prediction method was verified using the NASA IMS bearings dataset and C-MAPSS aeroengines dataset. The results indicate the superiority of our method for the RUL prediction of gradually degrading equipment compared to other mainstream machine learning methods. Full article

► Show Figures

Figure 1

12 pages, 4976 KB

Open AccessArticle

Combined Reinforcement Learning and CPG Algorithm to Generate Terrain-Adaptive Gait of Hexapod Robots

by Daxian Li, Wu Wei and Zhiying Qiu

Actuators 2023, 12(4), 157; https://doi.org/10.3390/act12040157 - 3 Apr 2023

Cited by 6 | Viewed by 4041

Abstract

Terrain adaptation research can significantly improve the motion performance of hexapod robots. In this paper, we propose a method that combines reinforcement learning with a central pattern generator (CPG) to enhance the terrain adaptation of hexapod robots in terms of gait planning. The [...] Read more.

Terrain adaptation research can significantly improve the motion performance of hexapod robots. In this paper, we propose a method that combines reinforcement learning with a central pattern generator (CPG) to enhance the terrain adaptation of hexapod robots in terms of gait planning. The hexapod robot’s complex task presents a high-dimensional observation and action space, which makes it challenging to directly apply reinforcement learning to robot control. Therefore, we utilize the CPG algorithm to generate the rhythmic gait while compressing the action space dimension of the agent. Additionally, the proposed method requires less internal sensor information, which exhibits strong applicability. Finally, we conduct experiments and deploy the proposed framework in the simulation environment. The results show that the terrain adaptation policy trained in our framework enables the hexapod robot to move more smoothly and efficiently on rugged terrain compared to the traditional CPG method. Full article

(This article belongs to the Section Actuators for Robotics)

► Show Figures

Figure 1

13 pages, 5785 KB

Open AccessArticle

A Study on the Design of Novel Slotless Motor Considering Winding Manufacture Process for a Collaborative Robot

by Junho Kang, Jeongwon Kim, Jungho Ahn, Inyeol Yoon, Hyunwoo Kim, Ju Lee and Donghoon Jung

Actuators 2023, 12(4), 156; https://doi.org/10.3390/act12040156 - 3 Apr 2023

Cited by 4 | Viewed by 4395

Abstract

In this paper, the design of novel slotless permanent magnet synchronous motor (PMSM) for a collaborative robot was studied considering the manufacture process of winding. The winding manufacture process of novel slotless PMSM was proposed in three steps. First, the two types of [...] Read more.

In this paper, the design of novel slotless permanent magnet synchronous motor (PMSM) for a collaborative robot was studied considering the manufacture process of winding. The winding manufacture process of novel slotless PMSM was proposed in three steps. First, the two types of coil units were manufactured based on the winding jig to assemble the coil units. Second, the coil unit was manufactured using the injection molding based on the plastic material such as polyphenylene sulfide (PPS). Third, the units of the coil were assembled to form a stator winding. Considering this manufacture process of winding, the slotless motor design was studied for the collaborative robot. For the design and analysis of slotless motor, finite element analysis (FEA) was performed through ANSYS Maxwell. The electromagnetic performance was analyzed according to the pole-slot combination. Considering the space of the collaborative robot, the basic model was designed. Based on the basic model, the electromagnetic performance was analyzed according to the design parameters such as the thickness of magnet and yoke and turns per slot. Considering the torque and current density, the final model was designed. To verify the FEA results, the slotless motor was manufactured and the experiment and FEA results were compared. Full article

► Show Figures

Figure 1

13 pages, 1885 KB

Open AccessArticle

Experimental Design of Fast Terminal Sliding Mode Control for Valve Regulation under Water Load Uncertainty for Precision Irrigation

by Jalu Ahmad Prakosa, Purwowibowo Purwowibowo, Edi Kurniawan, Sensus Wijonarko, Tatik Maftukhah, Dadang Rustandi, Enggar Banifa Pratiwi and Rahmanto Rahmanto

Actuators 2023, 12(4), 155; https://doi.org/10.3390/act12040155 - 3 Apr 2023

Cited by 5 | Viewed by 2557

Abstract

The application of control systems in precision irrigation is critical to ensure the accurate distribution of water in crops under various uncertainties. Shifts in the loading of the water supply on the control valve can be a significant uncertainty. Changes in weather and [...] Read more.

The application of control systems in precision irrigation is critical to ensure the accurate distribution of water in crops under various uncertainties. Shifts in the loading of the water supply on the control valve can be a significant uncertainty. Changes in weather and the uncertainty of the water level in the reservoir are also challenging issues. Sliding Mode Control (SMC) is a robust control technique that is simple to apply to deal with uncertainty, while Fast Terminal Sliding Mode Control (FTSMC) has the benefit of the rapid convergence. The DC electric motor, which is a common component of electric control valves, can be employed in designing control techniques for precision irrigation applications. This study aims to design a proposed experimental-based method, namely FTSMC for valve regulation under water load uncertainty for precision irrigation application. Modification of the signum function should be used to eliminate the chattering effect in real experiments.The results of experiments showed that the proposed method was superior to the conventional Proportional Integral Derivative (PID) and traditional SMC techniques in terms of overshoot, convergence rate and error. Because of those reasons, the FTSMC approach should be implemented on control valves against load uncertainty in precision irrigation applications. Full article

(This article belongs to the Section Control Systems)

► Show Figures

Figure 1

17 pages, 9493 KB

Open AccessArticle

Intelligent Fault Diagnosis Method through ACCC-Based Improved Convolutional Neural Network

by Chao Zhang, Qixuan Huang, Ke Yang and Chaoyi Zhang

Actuators 2023, 12(4), 154; https://doi.org/10.3390/act12040154 - 2 Apr 2023

Cited by 2 | Viewed by 2297

Abstract

Fault diagnosis plays an important role in improving the safety and reliability of complex equipment. Convolutional neural networks (CNN) have been widely used to diagnose faults due to their powerful feature extraction and learning capabilities. In practical industrial applications, the obtained signals always [...] Read more.

Fault diagnosis plays an important role in improving the safety and reliability of complex equipment. Convolutional neural networks (CNN) have been widely used to diagnose faults due to their powerful feature extraction and learning capabilities. In practical industrial applications, the obtained signals always are disturbed by strong and highly non-stationary noise, so the timing relationships of the signals should be highlighted more. However, most CNN-based fault diagnosis methods directly use a pooling layer, which may corrupt the timing relationship of the signals easily. More importantly, due to a lack of an attention mechanism, it is difficult to extract deep informative features from noisy signals. To solve the shortcomings, an intelligent fault diagnosis method is proposed in this paper by using an improved convolutional neural network (ICNN) model. Three innovations are developed. Firstly, the receptive field is used as a guideline to design diagnosis network structures, and the receptive field of the last layer is close to the length of the original signal, which can enable the network to fully learn each sample. Secondly, the dilated convolution is adopted instead of standard convolution to obtain larger-scale information and preserves the internal structure and temporal relation of the signal when performing down-sampling. Thirdly, an attention mechanism block named advanced convolution and channel calibration (ACCC) is presented to calibrate the feature channels, thus the deep informative features are distributed in larger weights while noise-related features are effectively suppressed. Finally, two experiments show the ICNN-based fault diagnosis method can not only process strong noise signals but also diagnose early and minor faults. Compared with other methods, it achieves the highest average accuracy at 94.78% and 90.26%, which are 6.53% and 7.70% higher than the CNN methods, respectively. In complex machine bearing failure conditions, this method can be used to better diagnose the type of failure; in voice calls, this method can be used to better distinguish between voice and noisy background sounds to improve call quality. Full article

(This article belongs to the Special Issue Electro-Mechanical Actuator, Diagnostic and Fault-Tolerant Control Systems)

► Show Figures

Figure 1

23 pages, 5525 KB

Open AccessArticle

Comparative Study on Effects of Input Configurations of Linear Quadratic Controller on Path Tracking Performance under Low Friction Condition

by Manbok Park and Seongjin Yim

Actuators 2023, 12(4), 153; https://doi.org/10.3390/act12040153 - 2 Apr 2023

Cited by 6 | Viewed by 2528

Abstract

This paper presents a comparative study on the effects of the input configurations of linear quadratic (LQ) controllers on path tracking performance under low friction conditions. For the last decade, the path tracking controller has adopted several control inputs, input configurations, and actuators. [...] Read more.

This paper presents a comparative study on the effects of the input configurations of linear quadratic (LQ) controllers on path tracking performance under low friction conditions. For the last decade, the path tracking controller has adopted several control inputs, input configurations, and actuators. However, these have not been compared with one another on a single frame in terms of common measures. For this reason, this paper compares input configurations of LQ controllers and available actuators in terms of common measures. For this purpose, the control inputs of the LQ controller were composed of front and rear steering and control yaw moment. By combining these control inputs, five input configurations of the LQ controller were set. If the control yaw moment is selected as a control input, then an actuator is needed to generate a control allocation, which should be adopted to convert the control yaw moment into longitudinal and lateral tire forces of actuators. As an actuator for control yaw moment generation, front/rear and 4-wheel steering, 4-wheel independent steering, braking, and driving were adopted. By applying the weighted least square based method, control allocation was formulated as a quadratic programming problem, which can be algebraically solved. For comparison on path tracking performance, new measures were adopted. To check the path tracking performance of each input configuration, a simulation was conducted on vehicle simulation software. From the simulation results, it was shown that front or 4-wheel steering itself is enough for path tracking on low friction roads and that the control yaw moment or an additional actuator is not recommended as a control input for path tracking on low friction roads. Full article

(This article belongs to the Special Issue Modeling, Dynamics, Intelligent Control, and Fault Diagnosis of Vehicle Systems)

► Show Figures

Figure 1

17 pages, 6489 KB

Open AccessArticle

Dynamic Vibration Absorbing Performance of 5-DoF Magnetically Suspended Momentum Wheel Based on Damping Regulation

by Biao Xiang and Hu Liu

Actuators 2023, 12(4), 152; https://doi.org/10.3390/act12040152 - 2 Apr 2023

Cited by 3 | Viewed by 1872

Abstract

The vibration performance is critical to the suspension control and the torque precision of the magnetically suspended momentum flywheel (MSMW). The translational and torsional vibration of the MSMW are investigated in this article, and the damping regulation method is proposed to improve the [...] Read more.

The vibration performance is critical to the suspension control and the torque precision of the magnetically suspended momentum flywheel (MSMW). The translational and torsional vibration of the MSMW are investigated in this article, and the damping regulation method is proposed to improve the anti-vibration performance of the MSMW. Firstly, the modellings of the MSMW, including the dynamic models and the displacement coordinate, are developed, and the comprehensive damping characteristics of the MSMW are investigated. Moreover, the transfer functions of the translational and the torsional vibrations are established using the dimensionless model, and the relationship between the dynamic response and the stiffness/damping coefficient is studied. Furthermore, the numerical simulations of the dynamic response of the translational and torsional vibration are conducted. Finally, the experiments are designed to verify the vibration characteristics of the MSMW, and the dynamic displacements are measured to analyze the anti-vibration performance of the proposed damping regulation method. The results indicate that the displacement deflection of the translational vibration is reduced by 68.8%, and the angle deflection of the torsional vibration is mitigated by 71.2% by regulating the damping coefficient. Full article

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

► Show Figures

Figure 1

11 pages, 3921 KB

Open AccessArticle

A 1-DOF Modular Robotic Hand Inspired by Human Two-Arm Cooperative Handling Strategy

by Yuhang Liu, Maocheng Zhao and Hongliang Hua

Actuators 2023, 12(4), 151; https://doi.org/10.3390/act12040151 - 31 Mar 2023

Viewed by 3341

Abstract

In the present article, a 1-DOF modular robotic hand inspired by a human two-arm cooperative handling strategy was presented to achieve flexible applications in robotic object grasping. The presented modular robotic hand was characterized as 1-DOF, modular, symmetrically designed and partly soft. The [...] Read more.

In the present article, a 1-DOF modular robotic hand inspired by a human two-arm cooperative handling strategy was presented to achieve flexible applications in robotic object grasping. The presented modular robotic hand was characterized as 1-DOF, modular, symmetrically designed and partly soft. The soft finger could produce independent elastic deformation and adapt to the object surface passively without the additional requirement of control. The modular hand is based on bus control technology, and up to 254 modular hands can be controlled simultaneously. The above characteristic of the modular hand could greatly improve the application flexibility of the robotic end-effector. The modularity of the robotic hand makes the multi-hand cooperative operation possible, which is a potential technology to eliminate the position error of the object. Based on the modular hand, a double-hand and quadruple-hand end-effector was developed, and some experimental tests were performed to verify its versatility and operating performance. The operating stability was also verified by kinematic modeling and numerical simulation. Full article

(This article belongs to the Section Actuators for Robotics)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Actuators, Volume 12, Issue 4 (April 2023) – 45 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI