Special Issue "Human Centered Actuators"

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

Deadline for manuscript submissions: closed (30 September 2013)

Special Issue Editor

Guest Editor
Prof. Dr. Delbert Tesar (Website)

Robotics Research Group, The University of Texas at Austin, 1 University Station, R9925, Austin, TX 78712, USA
Phone: +1 512 471 3039
Interests: robotics, electro-mechanical actuators, embedded intelligence; open architecture vehicles, ships, aircraft, machinery for manufacturing; human rehabilitation systems; long duration lunar base habitat operation

Special Issue Information

Dear Colleagues,

This is a collection of top quality papers published free of charge in Open Access form by the editorial board members, or those invited by the editorial office and the Editor-in-Chief. The papers should be long research papers (or review papers) with full and detailed summary of the author's own work done so far.

Prof. Dr. Delbert Tesar
Guest Editor

Submission

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. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as 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 refereed through a 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 300 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

Keywords

  • surgery tools and systems
  • piezoelectric actuators
  • metal alloy shape memory actuators
  • pneumatic actuators
  • hand/finger actuators
  • orthotic actuators
  • prosthetic actuators
  • wheelchair actuators
  • electro-mechanical actuators in healthcare

Published Papers (9 papers)

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Research

Jump to: Review

Open AccessArticle Energetic and Peak Power Advantages of Series Elastic Actuators in an Actuated Prosthetic Leg for Walking and Running
Actuators 2014, 3(1), 1-19; doi:10.3390/act3010001
Received: 12 September 2013 / Revised: 6 February 2014 / Accepted: 21 February 2014 / Published: 27 February 2014
Cited by 3 | PDF Full-text (391 KB) | HTML Full-text | XML Full-text
Abstract
A monoarticular series elastic actuator (SEA) reduces energetic and peak power requirements compared to a direct drive (DD) in active prosthetic ankle-foot design. Simulation studies have shown that similar advantages are possible for the knee joint. The aims of this paper were [...] Read more.
A monoarticular series elastic actuator (SEA) reduces energetic and peak power requirements compared to a direct drive (DD) in active prosthetic ankle-foot design. Simulation studies have shown that similar advantages are possible for the knee joint. The aims of this paper were to investigate the advantages of a monoarticular SEA-driven hip joint and to quantify the energetic benefit of an SEA-driven leg (with monoarticular hip, knee and ankle SEAs), assuming that damping (negative power) is passively achieved. The hip SEA provided minor energetic advantages in walking (up to 29%) compared to the knee and the ankle SEA. Reductions in required peak power were observed only for speeds close to preferred walking speed (18% to 27%). No energetic advantages were found in running, where a DD achieved the best performance when optimizing for energy. Using an SEA at each leg joint in the sagittal plane reduced the positive work by 14% to 39% for walking and by 37% to 75% for running. When using an SEA instead of a DD, the contribution of the three leg joints to doing positive work changed: the knee contributed less and the hip more positive work. For monoarticular SEAs, the ankle joint motor did most of the positive work. Full article
(This article belongs to the Special Issue Human Centered Actuators)
Open AccessArticle Double-Acting Sleeve Muscle Actuator for Bio-Robotic Systems
Actuators 2013, 2(4), 129-144; doi:10.3390/act2040129
Received: 5 November 2013 / Revised: 14 November 2013 / Accepted: 20 November 2013 / Published: 25 November 2013
Cited by 3 | PDF Full-text (650 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a new type of muscle-like actuator, namely double-acting (DA) sleeve muscle actuator, which is suitable for the actuation of biologically-inspired and biomedical robotic systems, especially those serving human-assistance purposes (prostheses, orthoses, etc.). Developed based on the traditional pneumatic [...] Read more.
This paper presents a new type of muscle-like actuator, namely double-acting (DA) sleeve muscle actuator, which is suitable for the actuation of biologically-inspired and biomedical robotic systems, especially those serving human-assistance purposes (prostheses, orthoses, etc.). Developed based on the traditional pneumatic muscle actuator, the new DA sleeve muscle incorporates a unique insert at the center. With the insert occupying the central portion of the internal volume, this new actuator enjoys multiple advantages relative to the traditional pneumatic muscle, including a consistent increase of force capacity over the entire range of motion, and a significant decrease of energy consumption in operation. Furthermore, the insert encompasses an additional chamber, which generates an extension force when pressurized. As such, this new actuator provides a unique bi-directional actuation capability, and, thus, has a potential to significantly simplify the design of a muscle actuator-powered robotic system. To demonstrate this new actuator concept, a prototype has been designed and fabricated, and experiments conducted on this prototype demonstrated the enhanced force capacity and the unique bi-directional actuation capability. Full article
(This article belongs to the Special Issue Human Centered Actuators)
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Open AccessArticle Self-Sensing Control of Nafion-Based Ionic Polymer-Metal Composite (IPMC) Actuator in the Extremely Low Humidity Environment
Actuators 2013, 2(4), 74-85; doi:10.3390/act2040074
Received: 6 August 2013 / Revised: 6 September 2013 / Accepted: 24 September 2013 / Published: 1 October 2013
Cited by 3 | PDF Full-text (397 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents feedforward, feedback and two-degree-of-freedom control applied to an Ionic Polymer-Metal Composite (IPMC) actuator. It presents a high potential for development of miniature robots and biomedical devices and artificial muscles. We have reported in the last few years that dehydration [...] Read more.
This paper presents feedforward, feedback and two-degree-of-freedom control applied to an Ionic Polymer-Metal Composite (IPMC) actuator. It presents a high potential for development of miniature robots and biomedical devices and artificial muscles. We have reported in the last few years that dehydration treatment improves the electrical controllability of bending in Selemion CMV-based IPMCs. We tried to replicate this controllability in Nafion-based IPMC. We found that the displacement of a Nafion-based IPMC was proportional to the total charge imposed, just as in the Selemion-CMV case. This property is the basis of self-sensing controllers for Nafion-based IPMC bending behavior: we perform bending curvature experiments on Nafion-based IPMCs, obtaining the actuator's dynamics and transfer function. From these, we implemented self-sensing controllers using feedforward, feedback and two-degree-of-freedom techniques. All three controllers performed very well with the Nafion-based IPMC actuator. Full article
(This article belongs to the Special Issue Human Centered Actuators)
Open AccessArticle Concept of a Series-Parallel Elastic Actuator for a Powered Transtibial Prosthesis
Actuators 2013, 2(3), 59-73; doi:10.3390/act2030059
Received: 21 February 2013 / Revised: 24 June 2013 / Accepted: 25 June 2013 / Published: 3 July 2013
Cited by 11 | PDF Full-text (697 KB) | HTML Full-text | XML Full-text
Abstract
The majority of the commercial transtibial prostheses are purely passive devices. They store energy in an elastic element during the beginning of a step and release it at the end. A 75 kg human, however, produces on average 26 J of energy [...] Read more.
The majority of the commercial transtibial prostheses are purely passive devices. They store energy in an elastic element during the beginning of a step and release it at the end. A 75 kg human, however, produces on average 26 J of energy during one stride at the ankle joint when walking at normal cadence and stores/releases 9 J of energy, contributing to energy efficient locomotion. According to Winter, a subject produces on average of 250W peak power at a maximum joint torque of 125 Nm. As a result, powering a prosthesis with traditional servomotors leads to excessive motors and gearboxes at the outer extremities of the legs. Therefore, research prototypes use series elastic actuation (SEA) concepts to reduce the power requirements of the motor. In the paper, it will be shown that SEAs are able to reduce the power of the electric motor, but not the torque. To further decrease the motor size, a novel human-centered actuator concept is developed, which is inspired by the variable recruitment of muscle fibers of a human muscle. We call this concept series-parallel elastic actuation (SPEA), and the actuator consists of multiple parallel springs, each connected to an intermittent mechanism with internal locking and a single motor. As a result, the motor torque requirements can be lowered and the efficiency drastically increased. In the paper, the novel actuation concept is explained, and a comparative study between a stiff motor, an SEA and an SPEA, which all aim at mimicking human ankle behavior, is performed. Full article
(This article belongs to the Special Issue Human Centered Actuators)
Open AccessArticle Optimal Passive Dynamics for Physical Interaction: Catching a Mass
Actuators 2013, 2(2), 45-58; doi:10.3390/act2020045
Received: 4 March 2013 / Revised: 12 April 2013 / Accepted: 22 April 2013 / Published: 2 May 2013
Cited by 2 | PDF Full-text (9391 KB) | HTML Full-text | XML Full-text
Abstract
For manipulation tasks in uncertain environments, intentionally designed series impedance in mechanical systems can provide significant benefits that cannot be achieved in software. Traditionally, the design of actuated systems revolves around sizing torques, speeds, and control strategies without considering the system’s passive [...] Read more.
For manipulation tasks in uncertain environments, intentionally designed series impedance in mechanical systems can provide significant benefits that cannot be achieved in software. Traditionally, the design of actuated systems revolves around sizing torques, speeds, and control strategies without considering the system’s passive dynamics. However, the passive dynamics of the mechanical system, including inertia, stiffness, and damping along with other parameters such as torque and stroke limits often impose performance limitations that cannot be overcome with software control. In this paper, we develop relationships between an actuator’s passive dynamics and the resulting performance for the purpose of better understanding how to tune the passive dynamics for catching an unexpected object. We use a mathematically optimal controller subject to force limitations to stop the incoming object without breaking contact and bouncing. The use of an optimal controller is important so that our results directly reflect the physical system’s performance. We analytically calculate the maximum velocity that can be caught by a realistic actuator with limitations such as force and stroke limits. The results show that in order to maximize the velocity of an object that can be caught without exceeding the actuator’s torque and stroke limits, a soft spring along with a strong damper will be desired. Full article
(This article belongs to the Special Issue Human Centered Actuators)
Open AccessArticle Analysis and Modeling of Linear-Switched Reluctance for Medical Application
Actuators 2013, 2(2), 27-44; doi:10.3390/act2020027
Received: 18 February 2013 / Revised: 25 March 2013 / Accepted: 7 April 2013 / Published: 22 April 2013
PDF Full-text (617 KB) | HTML Full-text | XML Full-text
Abstract
This paper focuses on the analysis, the modeling and the control of a linear-switched reluctance motor. The application under consideration is medical, and the actuator is to be used as a left ventricular assist device. The actuator has a cylindrical or tubular [...] Read more.
This paper focuses on the analysis, the modeling and the control of a linear-switched reluctance motor. The application under consideration is medical, and the actuator is to be used as a left ventricular assist device. The actuator has a cylindrical or tubular shape, with a mechanical unidirectional valve placed inside the mover, which provides a pulsatile flow of blood. The analytical expression of the effort based on the linear behavior of the actuator is given. The identification of the characteristics of the prototype actuator and the principle of position control is performed. A modeling of the actuator is proposed, taking into account the variation of inductance with respect to the position. The closed-loop position control of the actuator is performed by simulation. A controller with integral action and anticipatory action is implemented in order to compensate the effects of disturbing efforts and tracking deviations. Moreover, a magic switch is performed in the controller to avoid overshoots. The results show that the closed-loop response of the actuator is satisfactory. Full article
(This article belongs to the Special Issue Human Centered Actuators)
Open AccessArticle Optically Driven Mobile Integrated Micro-Tools for a Lab-on-a-Chip
Actuators 2013, 2(2), 19-26; doi:10.3390/act2020019
Received: 2 February 2013 / Revised: 18 March 2013 / Accepted: 29 March 2013 / Published: 11 April 2013
Cited by 1 | PDF Full-text (855 KB) | HTML Full-text | XML Full-text
Abstract
This study proposes an optically driven complex micromachine with an Archimedes microscrew as the mechanical power, a sphere as a coupler, and three knives as the mechanical tools. The micromachine is fabricated by two-photon polymerization and is portably driven by optical tweezers. [...] Read more.
This study proposes an optically driven complex micromachine with an Archimedes microscrew as the mechanical power, a sphere as a coupler, and three knives as the mechanical tools. The micromachine is fabricated by two-photon polymerization and is portably driven by optical tweezers. Because the microscrew can be optically trapped and rotates spontaneously, it provides driving power for the complex micro-tools. In other words, when a laser beam focuses on the micromachine, the microscrew is trapped toward the focus point and simultaneously rotates. A demonstration showed that the integrated micromachines are grasped by the optical tweezers and rotated by the Archimedes screw. The rotation efficiencies of the microrotors with and without knives are 1.9 rpm/mW and 13.5 rpm/mW, respectively. The micromachine can also be portably dragged along planed routes. Such Archimedes screw-based optically driven complex mechanical micro-tools enable rotation similar to moving machines or mixers, which could contribute to applications for a biological microfluidic chip or a lab-on-a-chip. Full article
(This article belongs to the Special Issue Human Centered Actuators)
Open AccessArticle State Space System Identification of 3-Degree-of-Freedom (DOF) Piezo-Actuator-Driven Stages with Unknown Configuration
Actuators 2013, 2(1), 1-18; doi:10.3390/act2010001
Received: 31 January 2013 / Revised: 28 February 2013 / Accepted: 4 March 2013 / Published: 8 March 2013
Cited by 2 | PDF Full-text (369 KB) | HTML Full-text | XML Full-text
Abstract
Due to their fast response, high accuracy and non-friction force, piezo-actuators have been widely employed in multiple degree-of-freedom (DOF) stages for various nano-positioning applications. The use of flexible hinges in these piezo-actuator-driven stages allows the elimination of the influence of friction and [...] Read more.
Due to their fast response, high accuracy and non-friction force, piezo-actuators have been widely employed in multiple degree-of-freedom (DOF) stages for various nano-positioning applications. The use of flexible hinges in these piezo-actuator-driven stages allows the elimination of the influence of friction and backlash clearance, as observed in other configurations; meanwhile it also causes more complicated stage performance in terms of dynamics and the cross-coupling effect between different axes. Based on the system identification technique, this paper presents the development of a model for the 3-DOF piezo-actuator-driven stages with unknown configuration, with its parameters estimated from the Hankel matrix by means of the maximum a posteriori (MAP) online estimation. Experiments were carried out on a commercially-available piezo-actuator-driven stage to verify the effectiveness of the developed model, as compared to other methods. The results show that the developed model is able to predict the stage performance with improved accuracy, while the model parameters can be well updated online by using the MAP estimation. These capabilities allow investigation of the complicated stage performance and also provide a starting point from which the mode-based control scheme can be established for improved performance. Full article
(This article belongs to the Special Issue Human Centered Actuators)

Review

Jump to: Research

Open AccessReview Overview of Actuated Arm Support Systems and Their Applications
Actuators 2013, 2(4), 86-110; doi:10.3390/act2040086
Received: 8 August 2013 / Revised: 12 September 2013 / Accepted: 26 September 2013 / Published: 2 October 2013
Cited by 7 | PDF Full-text (417 KB) | HTML Full-text | XML Full-text
Abstract
Arm support systems provide support throughout daily tasks, training or in an industrial environment. During the last decades a large diversity of actuated arm support systems have been developed. To analyze the actuation principles in these systems, an overview of actuated arm [...] Read more.
Arm support systems provide support throughout daily tasks, training or in an industrial environment. During the last decades a large diversity of actuated arm support systems have been developed. To analyze the actuation principles in these systems, an overview of actuated arm support systems is provided. This overview visualizes the current trends on research and development of these support systems and distinguishes three categories. These categories depend mainly on the functional status of the user environment, which defines the specifications. Therefore, the actuated arm support systems are classified according to their user environment, namely: ambulatory, rehabilitation and industrial. Furthermore, three main actuation principles and three mechanical construction principles have been identified. Full article
(This article belongs to the Special Issue Human Centered Actuators)
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