Design and Application of Actuators with Multi-DOF Movement-2nd Edition

A special issue of Actuators (ISSN 2076-0825). This special issue belongs to the section "Miniaturized and Micro Actuators".

Deadline for manuscript submissions: 15 February 2026 | Viewed by 8326

Special Issue Editors


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Guest Editor
Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan
Interests: micro voice coil motor; precision measurement; geometric error measurement and system design for machine tools; 3D optical scanner; laser-based autofocusing microscopy; opto-electronic sensing and applications
Special Issues, Collections and Topics in MDPI journals
Department of Mechanical and Electromechanical Engineering, National Sun Yat-sen University, Tainan, Taiwan
Interests: PZT actuator; energy harvester; force/torque sensor; ultrasonic transducer; precision machinery; parallel kinematic mechanism
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Ansys Inc., Hsinchu, Taiwan
Interests: MEMS; electro-thermal actuator; PZT actuator; solenoid valves; torque actuator

Special Issue Information

Dear Colleagues,

We are pleased to invite you to submit your paper(s) to our Special Issue of Actuators (ISSN 2076-0825) on “Design and Application of Actuators with Multi-DOF Movement-2nd Edition”. Both original research and review articles are welcome.

With the increasing demand for industrial automation and robotics worldwide, actuators with multi-degree-of-freedom (DOF) motion capabilities have been developed to enable more complex movements in machines and robots. Traditionally, multi-DOF systems have been used to control the joints and movements of humanoid robots, using multiple motors to mimic the movement of the human body. However, these systems often come with an increased weight and size. In recent years, various multi-DOF actuators have been developed and designed to achieve multi-axis or multi-DOF motion, along with advances in materials science, stretchable electronics, and mechatronics. These actuators offer multifunctionality, low costs, a fast response, high repeatability, and a small size, making them a promising solution for industrial automation and robotic applications. Applications of multi-DOF actuators cover a wide range of fields, such as robotics, haptic devices for augmented reality systems, precision measurement, camera modules, data storage devices, projectors, optics, optoelectronics, and medical and healthcare engineering, among others. The development of multi-DOF actuators is expected to expand substantially in the years and decades ahead. To highlight the current status and perspectives, this Special Issue invites contributions, including research and review articles, that cover all aspects of multi-DOF actuators, including, but not limited to: novel designs of multi-DOF actuators; theory, modeling, and control; simulation; experimental methodology; multi-degree-of-freedom movement; manufacturing and processing; 3D printing for multi-DOF actuators; and applications in research, industry, and education.

Prof. Dr. Chien-Sheng Liu
Dr. Yu-Jen Wang
Dr. Chien-Yu Chen
Guest Editors

Manuscript Submission Information

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Keywords

  • multi-DOF
  • multi-DOF actuators
  • multi-DOF movements
  • humanoid robots
  • robotics

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Published Papers (6 papers)

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Research

17 pages, 2319 KiB  
Article
Coordinating the Redundant DOFs of Humanoid Robots
by Pietro Morasso
Actuators 2025, 14(7), 354; https://doi.org/10.3390/act14070354 - 18 Jul 2025
Viewed by 82
Abstract
The new generation of robots (Industry 5.0 and beyond) is expected to be accompanied by the massive introduction of autonomous and cooperative agents in our society, both in the industrial and service sectors. Cooperation with humans will be simplified by humanoid robots with [...] Read more.
The new generation of robots (Industry 5.0 and beyond) is expected to be accompanied by the massive introduction of autonomous and cooperative agents in our society, both in the industrial and service sectors. Cooperation with humans will be simplified by humanoid robots with a similar kinematic outline and a similar kinematic redundancy, which is required by the diversity of tasks that will be performed. A bio-inspired approach is proposed for coordinating the redundant DOFs of such agents. This approach is based on the ideomotor theory of action, combined with the passive motion paradigm, to implicitly address the degrees of freedom problem, without any kinematic inversion, while producing coordinated motor patterns structured according to the typical features of biological motion. At the same time, since the approach is force-field-based, it allows us to integrate the computational loop parallel modules that exploit the redundancy of the system for satisfying geometric or kinematic constraints implemented by appropriate repulsive force fields. Moreover, the model is expanded to include dynamic constraints associated with the Lagrangian dynamics of the humanoid robot to improve the energetic efficiency of the generated actions. Full article
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26 pages, 2703 KiB  
Article
Design of Actuators for a Humanoid Robot with Anthropomorphic Characteristics and Running Capability
by Chathura Semasinghe, Drake Taylor and Siavash Rezazadeh
Actuators 2025, 14(5), 243; https://doi.org/10.3390/act14050243 - 13 May 2025
Viewed by 2785
Abstract
In this paper, we present the details of the actuator design for our humanoid robot, Mithra. Mithra has been designed to match an average adult human in terms of kinematic and kinetic characteristics. This poses various challenges in actuator design that we have [...] Read more.
In this paper, we present the details of the actuator design for our humanoid robot, Mithra. Mithra has been designed to match an average adult human in terms of kinematic and kinetic characteristics. This poses various challenges in actuator design that we have addressed in this work. First, we discuss how the high-level design can help in achieving anthropomorphic traits. Next, the detailed design is verified and finalized using stress and fatigue analyses. Further, we conduct experiments to validate the actuator’s bandwidth and backdrivability, and discuss the outcomes in comparison with human characteristics. The results show that Mithra’s actuators have sufficient structural strength to withstand high running forces, and at the same time, provide human-like traits and capabilities to accommodate human-inspired control paradigms. Full article
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26 pages, 8954 KiB  
Article
A Two-Segment Continuum Robot with Piecewise Stiffness for Tracheal Intubation and Active Decoupling
by Jianhao Tang, Lingfeng Sang, Junjie Tian, Qiqi Pan, Yuan Han, Wenxian Li, Yu Tian and Hongbo Wang
Actuators 2025, 14(5), 228; https://doi.org/10.3390/act14050228 - 5 May 2025
Viewed by 541
Abstract
This study presents a two-segment continuum robot with piecewise stiffness, designed to enhance the precision, adaptability, and safety of tracheal intubation procedures. The robot employs a continuum manipulator (CM) as its end-effector, featuring a proximal segment (PS) with an aluminum alloy interlocking joint, [...] Read more.
This study presents a two-segment continuum robot with piecewise stiffness, designed to enhance the precision, adaptability, and safety of tracheal intubation procedures. The robot employs a continuum manipulator (CM) as its end-effector, featuring a proximal segment (PS) with an aluminum alloy interlocking joint, which provides high axial stiffness for stable insertion, and a distal segment (DS) with a micro-nano resin-based notched structure, offering increased flexibility and compliance to navigate complex anatomical structures such as the epiglottis and vocal cords, thereby reducing airway trauma. To describe the motion behavior of the robot, a piecewise variable curvature kinematic model is developed, capturing the deformation characteristics of each segment under actuation. Furthermore, a piecewise stiffness analysis is conducted to determine the axial and bending stiffness of each segment, ensuring an appropriate balance between stability and flexibility. To enhance control precision, an active tendon-driven decoupling control strategy is introduced, effectively minimizing the interaction forces between flexible segments and improving end-effector maneuverability. The results demonstrate that the proposed design significantly improves the adaptability of the tracheal intubation robot, ensuring controlled insertion while reducing the risk of excessive force on the airway walls. This study provides theoretical and technical insights into the mechanical design and control strategies of continuum robots, contributing to the safety and efficiency of tracheal intubation. Full article
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16 pages, 3356 KiB  
Article
Integrated Whole-Body Control and Manipulation Method Based on Teacher–Student Perception Information Consistency
by Shuqi Liu, Yufeng Zhuang, Shuming Hu, Yanzhu Hu and Bin Zeng
Actuators 2025, 14(3), 131; https://doi.org/10.3390/act14030131 - 7 Mar 2025
Viewed by 838
Abstract
In emergency scenarios, we focus on studying how to manipulate legged robot dogs equipped with robotic arms to move and operate in a small space, known as legged emergency manipulation. Although the legs of the robotic dog are mainly used for movement, we [...] Read more.
In emergency scenarios, we focus on studying how to manipulate legged robot dogs equipped with robotic arms to move and operate in a small space, known as legged emergency manipulation. Although the legs of the robotic dog are mainly used for movement, we found that implementing a whole-body control strategy can enhance its operational capabilities. This means that the robotic dog’s legs and mechanical arms can be synchronously controlled, thus expanding its working range and mobility, allowing it to flexibly enter and exit small spaces. To this end, we propose a framework that can utilize visual information to provide feedback for whole-body control. Our method combines low-level and high-level strategies: the low-level strategy utilizes all degrees of freedom to accurately track the body movement speed of the robotic dog and the position of the end effector of the robotic arm; the advanced strategy is based on visual input, intelligently planning the optimal moving speed and end effector position. At the same time, considering the uncertainty of visual guidance, we integrate fully supervised learning into the advanced strategy to construct a teacher network and use it as a benchmark network for training the student network. We have rigorously trained these two levels of strategies in a simulated environment, and through a series of extensive simulation validations, we have demonstrated that our method has significant improvements over baseline methods in moving various objects in a small space, facing different configurations and different target objects. Full article
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16 pages, 8423 KiB  
Article
Development of Spherical Actuator with L-Shaped Yoke
by Yu-Wen Huang, Hao-Wen Chung, Yu-Ming Chen, Chien-Sheng Liu and Ming-Fu Chen
Actuators 2025, 14(1), 30; https://doi.org/10.3390/act14010030 - 15 Jan 2025
Viewed by 1218
Abstract
In this paper, a two-DOF L-shaped yoke spherical actuator based on the principle of traditional voice coil actuators is developed. By utilizing the shape characteristics of the yoke and the magnetization direction of the magnet, the magnetic flux is concentrated and the magnet [...] Read more.
In this paper, a two-DOF L-shaped yoke spherical actuator based on the principle of traditional voice coil actuators is developed. By utilizing the shape characteristics of the yoke and the magnetization direction of the magnet, the magnetic flux is concentrated and the magnet is shared, thereby improving the performance of the actuator. In the design process, SOLIDWORKS 2018 software is used for design modeling and assembly simulation, ANSYS Maxwell 2018 software is employed for magnetic circuit analysis and electromagnetic simulation, while MATLAB is utilized for analyzing the dynamic characteristics through a mathematical model. A prototype was also fabricated, and torque measurement experiments were conducted to verify the performance and feasibility of the proposed design. Full article
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13 pages, 4679 KiB  
Article
Identification Algorithm for Stability Improvement of Welding Robot End-Effector
by Lijian Liu, Yongkang Zhang, Bin Wei and Guang Yang
Actuators 2024, 13(5), 175; https://doi.org/10.3390/act13050175 - 6 May 2024
Viewed by 1802
Abstract
Aiming to solve the problem that the significant error between the actual joint torque and the calculated joint torque of a welding robot leads to the vibration of the end-effector, which in turn affects the stability of the end-effector, this paper proposes a [...] Read more.
Aiming to solve the problem that the significant error between the actual joint torque and the calculated joint torque of a welding robot leads to the vibration of the end-effector, which in turn affects the stability of the end-effector, this paper proposes a identification algorithm based on the Weighted Least Squares Genetic Algorithm (WLS-GA) to construct and solve the dynamical model to obtain the accurate dynamical parameters. Firstly, a linear model of welding robot dynamics is derived. The fifth-order optimal Fourier series excitation trajectory is designed to collect experimental data such as joint torque. Then, a rough solution of the parameters to be recognized is obtained by solving the dynamics model through the Weighted Least Squares (WLS) method, the search space is determined based on the rough solution, and the optimal solution is obtained by using the Genetic Algorithm (GA) to perform a quadratic search in the search space. Finally, the identification data obtained from the algorithm is analyzed and compared with the experimental data. The results show that the error between the identification data obtained using the WLS-GA identification algorithm and the experimental data is relatively small. The results show that the identification data obtained using the WLS-GA identification algorithm have less error than the experimental data, taking the Root Mean Square (RMS) value of the joint torque error obtained using the weighted least squares algorithm as a criterion. The accuracy of the WLS-GA identification algorithm can be improved by up to 66.85% compared with that of the weighted least squares algorithm and by up to 78.0% compared with that of the Ordinary Least Squares (OLS) algorithm. In summary, the WLS-GA identification algorithm can accurately identify the dynamic parameters of the welding robot and more accurately construct a dynamic model to solve the effect of joint torque error on the control characteristics of the welding robot. It can improve the stability of the end-effector of the welding robot to ensure the quality of the automobile body and beam welding and welding speed. Full article
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