Special Issue "Pneumatic Actuators"

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

Deadline for manuscript submissions: closed (31 July 2018)

Special Issue Editor

Guest Editor
Dr. Steve Davis

School of Computing, Science & Engineering, University of Salford, Greater Manchester, UK
Website | E-Mail
Interests: soft robotics; pneumatic muscles; end effectors; automation for food; healthcare robotics

Special Issue Information

Dear Colleagues,

Pneumatic actuators have been used in robotics for many years. However, historically, they have only been used in applications that use bang-bang control, e.g., industrial grippers or factory automation. In recent years, pneumatic actuation has seen increasing application in all areas of robotics. This has been a result of the development of better control techniques, more accurate mathematical models and the development of new actuator designs. Additionally, increased interest in compliant actuators and systems, as well as soft robots which are highly deformable, inherently safe and often do not use conventional actuators has led to the development of new pneumatic actuators being produced. This Special Issue aims to present advances in both the development of novel pneumatic actuators and the use of pneumatic actuators in new application domains.

Dr. Steve Davis
Guest Editor

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 350 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

  • pneumatic actuators
  • soft actuators
  • pneumatic muscles
  • fluidic actuators

Published Papers (7 papers)

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Editorial

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Open AccessEditorial Pneumatic Actuators
Actuators 2018, 7(3), 62; https://doi.org/10.3390/act7030062
Received: 5 September 2018 / Accepted: 12 September 2018 / Published: 13 September 2018
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(This article belongs to the Special Issue Pneumatic Actuators)

Research

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Open AccessFeature PaperArticle Sleeved Bending Actuators for Soft Grippers: A Durable Solution for High Force-to-Weight Applications
Actuators 2018, 7(3), 40; https://doi.org/10.3390/act7030040
Received: 6 June 2018 / Revised: 12 July 2018 / Accepted: 13 July 2018 / Published: 17 July 2018
Cited by 1 | PDF Full-text (7043 KB) | HTML Full-text | XML Full-text
Abstract
Soft grippers are known for their ability to interact with objects that are fragile, soft or of an unknown shape, as well as humans in collaborative robotics applications. However, state-of-the-art soft grippers lack either payload capacity or durability, which limits their use in
[...] Read more.
Soft grippers are known for their ability to interact with objects that are fragile, soft or of an unknown shape, as well as humans in collaborative robotics applications. However, state-of-the-art soft grippers lack either payload capacity or durability, which limits their use in industrial applications. In fact, high force density pneumatic soft grippers require high strain and operating pressure, both of which impair their durability. This work presents a new sleeved bending actuator for soft grippers that is capable of high force density and durability. The proposed actuator is based on design principles previously proven to improve the life of pneumatic artificial muscles, where a sleeve provides a uniform reinforcement that reduces local stresses and strains in the inflated membrane. The sleeved bending actuator features a silicone membrane and an external two-material sleeve that can support high pressures while providing a flexible grip. The proposed sleeved bending actuators are validated through two grippers, sized according to foreseen soft gripper applications: A small gripper for drone perching and lightweight food manipulation, and a larger one for the manipulation of heavy material (>5 kg) of various weights and sizes. Performance assessment shows that these grippers have payloads up to 5.2 kg and 20 kg, respectively. Durability testing of the grippers demonstrates that the grippers have an expected lifetime ranging from 263,000 cycles to more than 700,000 cycles. The grippers are tested in various settings, including the integration of a gripper into a Phantom 2 quadcopter, a perching demonstration, as well as the gripping of light and heavy food items. Experiments show that sleeved bending actuators constitute a promising avenue for durable and strong soft grippers. Full article
(This article belongs to the Special Issue Pneumatic Actuators)
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Open AccessArticle Control of Pneumatic Artificial Muscles Using Local Cyclic Inputs and Genetic Algorithm
Actuators 2018, 7(3), 36; https://doi.org/10.3390/act7030036
Received: 26 April 2018 / Revised: 29 June 2018 / Accepted: 29 June 2018 / Published: 3 July 2018
Cited by 1 | PDF Full-text (8562 KB) | HTML Full-text | XML Full-text
Abstract
Recently, lightweight and flexible soft actuators have attracted interest from robotics researchers. We focused on pneumatic rubber artificial muscle (PAM) as a high-output soft actuator. The high compliance of PAM allows a robot to adapt flexibly to the environment without many external sensors.
[...] Read more.
Recently, lightweight and flexible soft actuators have attracted interest from robotics researchers. We focused on pneumatic rubber artificial muscle (PAM) as a high-output soft actuator. The high compliance of PAM allows a robot to adapt flexibly to the environment without many external sensors. Although PAM has these characteristics, it is difficult to control because of the nonlinearity between the input and output and the delay of air response. This limits the accuracy of artificial muscles and complicates motion planning. Therefore, we considered that PAM can be driven by simplified control laws, so that the entire system shows emergent motion guided by metaheuristics. We developed a legged robot with two joints driven by PAMs. Each PAM was controlled with a cyclic signal, and the genetic algorithm was applied to optimize these signals. We tested to check whether the behavior of the PAMs is changed by the genetic algorithm using three simple performance indexes. We found out that although the genetic algorithm adjusted the local cyclic inputs appropriately according to each performance index, the time-varying characteristic of PAMs disturbed the monotonic increment of the evaluation values. We also discovered that by only adjusting the input timing, the leg develops a limitation in robustness. Full article
(This article belongs to the Special Issue Pneumatic Actuators)
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Open AccessArticle A 3D Printed Linear Pneumatic Actuator for Position, Force and Impedance Control
Actuators 2018, 7(2), 24; https://doi.org/10.3390/act7020024
Received: 27 April 2018 / Revised: 18 May 2018 / Accepted: 22 May 2018 / Published: 24 May 2018
Cited by 1 | PDF Full-text (2815 KB) | HTML Full-text | XML Full-text
Abstract
Although 3D printing has the potential to provide greater customization and to reduce the costs of creating actuators for industrial applications, the 3D printing of actuators is still a relatively new concept. We have developed a pneumatic actuator with 3D-printed parts and placed
[...] Read more.
Although 3D printing has the potential to provide greater customization and to reduce the costs of creating actuators for industrial applications, the 3D printing of actuators is still a relatively new concept. We have developed a pneumatic actuator with 3D-printed parts and placed sensors for position and force control. So far, 3D printing has been used to create pneumatic actuators of the bellows type, thus having a limited travel distance, utilizing low pressures for actuation and being capable of only limited force production and response rates. In contrast, our actuator is linear with a large travel distance and operating at a relatively higher pressure, thus providing great forces and response rates, and this the main novelty of the work. We demonstrate solutions to key challenges that arise during the design and fabrication of 3D-printed linear actuators. These include: (1) the strategic use of metallic parts in high stress areas (i.e., the piston rod); (2) post-processing of the inner surface of the cylinder for smooth finish; (3) piston head design and seal placement for strong and leak-proof action; and (4) sensor choice and placement for position and force control. A permanent magnet placed in the piston head is detected using Hall effect sensors placed along the length of the cylinder to measure the position, and pressure sensors placed at the supply ports were used for force measurement. We demonstrate the actuator performing position, force and impedance control. Our work has the potential to open new avenues for creating less expensive, customizable and capable actuators for industrial and other applications. Full article
(This article belongs to the Special Issue Pneumatic Actuators)
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Open AccessArticle Investigating the Effect of a Mechanism Combined with a Speed-Increasing Gear and a Pneumatic Artificial Muscle
Actuators 2018, 7(2), 22; https://doi.org/10.3390/act7020022
Received: 4 April 2018 / Revised: 4 May 2018 / Accepted: 9 May 2018 / Published: 11 May 2018
Cited by 1 | PDF Full-text (3364 KB) | HTML Full-text | XML Full-text
Abstract
The lightness and softness of pneumatic artificial muscles (PAMs) contribute to their safe use in mechanical devices involved with humans. However, a PAM has limited range of motion (ROM) and a stroke-dependent output force. In this paper, a mechanism combined with a PAM
[...] Read more.
The lightness and softness of pneumatic artificial muscles (PAMs) contribute to their safe use in mechanical devices involved with humans. However, a PAM has limited range of motion (ROM) and a stroke-dependent output force. In this paper, a mechanism combined with a PAM and a speed-increasing gear was developed to improve the tradeoff relationship between the ROM and output force and to verify its benefits in order to enhance the convenience of using PAMs. The gear enhanced the ROM and back-drivability of the PAM, which is beneficial for device safety in daily use. We first designed a mechanism consisting of an antagonistic system-driven PAM and the gear, and then simulated the relationship between the ROM and output force of the mechanism. The effectiveness of the mechanism including the gear was compared with a non-gear mechanism with multiple PAMs. We prototyped the PAM mechanism with and without the gear, and their ROMs, impact absorption, and viscoelasticity were experimentally investigated. Results showed that the gear effectively improved both ROM and output torque below a certain load; moreover, the gear ratio and air pressure had large effects on the external static and dynamic forces, respectively. We confirmed comprehensively the effect and feasibility of the mechanism. Full article
(This article belongs to the Special Issue Pneumatic Actuators)
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Open AccessArticle Modeling the Static Force of a Festo Pneumatic Muscle Actuator: A New Approach and a Comparison to Existing Models
Actuators 2017, 6(4), 33; https://doi.org/10.3390/act6040033
Received: 7 September 2017 / Revised: 15 October 2017 / Accepted: 20 October 2017 / Published: 2 November 2017
Cited by 6 | PDF Full-text (976 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a new approach for modeling the static force characteristic of Festo pneumatic muscle actuators (PMAs) will be presented. The model is physically motivated and therefore gives a deeper understanding of the Festo PMA. After introducing the new model, it will
[...] Read more.
In this paper, a new approach for modeling the static force characteristic of Festo pneumatic muscle actuators (PMAs) will be presented. The model is physically motivated and therefore gives a deeper understanding of the Festo PMA. After introducing the new model, it will be validated through a comparison to a measured force map of a Festo DMSP-10-250 and a DMSP-20-300, respectively. It will be shown that the error between the new model and the measured data is below 4.4% for the DMSP-10-250 and below 2.35% for the DMSP-20-300. In addition, the quality of the presented model will be compared to the quality of existing models by comparing the maximum error. It can be seen that the newly introduced model is closer to the measured force characteristic of a Festo PMA than any existing model. Full article
(This article belongs to the Special Issue Pneumatic Actuators)
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Open AccessArticle Pneumatic Multi-Pocket Elastomer Actuators for Metacarpophalangeal Joint Flexion and Abduction-Adduction
Actuators 2017, 6(3), 27; https://doi.org/10.3390/act6030027
Received: 22 July 2017 / Revised: 4 September 2017 / Accepted: 6 September 2017 / Published: 19 September 2017
Cited by 4 | PDF Full-text (14977 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
During recent years, interest has been rising towards developing fluidic fiber-reinforced elastomer actuators for wearable soft robotics used in hand rehabilitation and power-assist. However, they do not enable finger abduction-adduction, which plays an important role in activities of daily living, when grasping larger
[...] Read more.
During recent years, interest has been rising towards developing fluidic fiber-reinforced elastomer actuators for wearable soft robotics used in hand rehabilitation and power-assist. However, they do not enable finger abduction-adduction, which plays an important role in activities of daily living, when grasping larger objects. Furthermore, the developed gloves often do not have separate control of joints, which is important for doing various common rehabilitation motions. The main obstacle for the development of a fully-assisting glove is moving a joint with multiple degrees of freedom. If the functions are built into the same structure, they are naturally coupled and affect each other, which makes them more difficult to design and complex to control than a simple flexion-extension actuator. In this study, we explored the key design elements and fabrication of pneumatic multi-pocket elastomer actuators for a soft rehabilitation glove. The goal was to gain more control over the metacarpophalangeal joint’s response by increasing the degree of actuation. Three main functional designs were tested for achieving both flexion and abduction-adduction. Five prototypes, with four different actuator geometries and four different reinforcement types, were designed and fabricated. They were evaluated by recording their free motion with motion capture and measuring their torque output using a dummy finger. Results showed the strengths and weaknesses of each design in separating the control of the two functions. We discuss the different improvements that are needed in order to make each design plausible for developing an actuator that meets the requirements for full assist of the hand’s motions. In conclusion, we show that it is possible to produce multi-pocket actuators for assisting MCP joint motion in both flexion and abduction-adduction, although coupling between the separate functions is still problematic and should be considered further. Full article
(This article belongs to the Special Issue Pneumatic Actuators)
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