Special Issue "Variable Stiffness Actuators"

A special issue of Actuators (ISSN 2076-0825).

Deadline for manuscript submissions: 31 July 2020.

Special Issue Editors

Prof. Dr.-Ing. Dr. med. Dr. h. c. Steffen Leonhardt
Website
Guest Editor
Helmholtz Institute of Biomedical Engineering, RWTH Aachen University, Aachen, Germany
Interests: biomedical engineering; control engineering; rehabilitation robotics; compliant actuators
Special Issues and Collections in MDPI journals
Dipl.-Ing. Bernhard Penzlin
Website
Guest Editor
Helmholtz Institute of Biomedical Engineering, RWTH Aachen University, Aachen, Germany
Interests: mechatronic systems; compliant actuators; rehabilitation robotics; exoskeleton
Dr.-Ing. Chuong Ngo
Website
Guest Editor
Medical Information Technology, Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
Interests: variable stiffness actuators; control engineering; physiological modeling; motion analysis; respiration

Special Issue Information

Dear Colleagues,

The application of compliant actuators is pursued for various reasons, including safe human-machine interactions, the imitation of physiological muscle characteristics, the reduction of peak torque, peak performance, and energy consumption. The mechanical design and technical implementation of the variable compliant actuators is a key challenge. As multivariable systems, actuator systems equipped with adjustable compliance require special control methods. Some application scenarios for these modern actuator topologies are bipedal gait, support at work or in everyday life, rehabilitation robotics, and industrial motion control.

Contributions from all areas of compliant actuators are welcome in this Special Issue, particularly the following:

  • Rehabilitation Robotics: Variable stiffness actuators to support the lower limb;
  • Design: Variable Stiffness Actuator design and experimental validation of prototypes;
  • Energy Analysis: Efficiency enhancement with actuators containing elastic elements;
  • Support in everyday life: Actuators for motion support (e.g., elderly people);
  • Control Systems: Control of systems including compliant actuators;
  • Industrial Application: VSA for use in motion support and automated processes.

Prof. Dr.-Ing. Dr. med. Dr. h. c. Steffen Leonhardt
Dipl.-Ing. Bernhard Penzlin
Dr.-Ing. Chuong Ngo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Actuators is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Control systems
  • Human robot interaction
  • Energy efficiency
  • Compliant actuators
  • Rehabilitation robotics
  • Controllable stiffness actuators
  • Actuator design

Published Papers (2 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Open AccessArticle
A Concentric Design of a Bypass Magnetorheological Fluid Damper with a Serpentine Flux Valve
Actuators 2020, 9(1), 16; https://doi.org/10.3390/act9010016 - 06 Mar 2020
Abstract
This work presents a new concentric design structure of a bypass magnetorheological (MR) damper with a serpentine flux valve type. In this design, the serpentine valve is installed not in the middle of the piston but on the bypass channel of the damper. [...] Read more.
This work presents a new concentric design structure of a bypass magnetorheological (MR) damper with a serpentine flux valve type. In this design, the serpentine valve is installed not in the middle of the piston but on the bypass channel of the damper. However, to make it less bulky, the location of the valve installation is chosen to be in line with the cylinder axis, which is different from the common configuration of the bypass damper. With the proposed design concept, the performance flexibility of the bypass configuration and the compactness of the piston valve configuration can be accomplished. In this study, these benefits were demonstrated by firstly deriving an analytical model of the proposed MR damper focusing on the bypass concentric valve structure, which is vital in determining the damping force characteristics. The prototype of MR damper was also fabricated and characterized using the dynamic test machine. The simulation results show that the damping force could be adjusted from 20 N in the off-state to around 600 N in the on-state with 0.3 A of excitation current. In the experiments, during low piston velocity measurement, the on-state results from the simulation were generally in good agreement with the experimental results. However, with the increase in piston velocity, the deviation between the simulation and the experiment gets higher. The deviations are most probably due to seal frictions that were not accounted for in the model. The seal friction is probably dominant as the seals in the prototype need to be prepared for handling higher fluid pressure. As a result, the frictions are quite prevalent and significantly affect the measured off-state damping forces as well, where it was recorded ten times higher than the predicted values from the model. Nevertheless, although there were deviations, the dynamic range of the concentric bypass structure is still 1.5 times higher than the conventional structure and the new structure can be potentially explored more to achieve an improved MR damper design. Full article
(This article belongs to the Special Issue Variable Stiffness Actuators)
Show Figures

Figure 1

Open AccessArticle
Design and Analysis of a Clutched Parallel Elastic Actuator
Actuators 2019, 8(3), 67; https://doi.org/10.3390/act8030067 - 05 Sep 2019
Abstract
Various actuator topologies are discussed for the purpose of powering periodic processes and particularly walking robots. The Clutched Parallel Elastic Actuator (CPEA) is proposed to reduce the energy consumption of active exoskeletons. A nonlinear model of the CPEA is presented in addition to [...] Read more.
Various actuator topologies are discussed for the purpose of powering periodic processes and particularly walking robots. The Clutched Parallel Elastic Actuator (CPEA) is proposed to reduce the energy consumption of active exoskeletons. A nonlinear model of the CPEA is presented in addition to the mechanical design. The CPEA prototype is operated with a passive load on the walking trajectory of the hip joint. The actuator is controlled with a cascaded position control and a superimposed Iterative Learning Controller (ILC). The controller was chosen to ensure comparability between active and deactivated spring operation. The application of the CPEA has the potential to increase efficiency in the design of exoskeletons. Full article
(This article belongs to the Special Issue Variable Stiffness Actuators)
Show Figures

Figure 1

Back to TopTop