scholarly journals Soft Pneumatic Artificial Muscles With Low Threshold Pressures for a Cardiac Compression Device

2013 ◽  
Author(s):  
Steven C. Obiajulu ◽  
Ellen T. Roche ◽  
Frank A. Pigula ◽  
Conor J. Walsh
Keyword(s):  
Response Times ◽  
Local Stress ◽  
Artificial Muscles ◽  
Force Output ◽  
Stress Concentrations ◽  
Nylon Mesh ◽  
Cardiac Compression ◽  
Pneumatic Artificial Muscles ◽  
Low Threshold ◽  
Actuator Design

In this paper, we present the design, fabrication and characterization of fully soft pneumatic artificial muscles (PAMs) with low threshold pressures that are intended for direct cardiac compression (DCC). McKibben type PAMs typically have a threshold pressure of at least 100 kPa and require rigid end fittings which may damage soft tissue and cause local stress concentrations, and thus failure points in the actuator. The actuator design we present is a variant on the McKibben PAM with the following key differences: the nylon mesh is embedded in the elastomeric tube, and closure of the end of the tube is achieved without rigid ends. The actuators were tested to investigate the effects of mesh geometry and elastomer material on force output, contraction, and rise time. Lower initial mean braid angles and softer elastomer materials provided the best force, contraction, and rise times; Up to 50 N of force, 24% contraction, and response times of 0.05 s were achieved at 100 kPa. The actuators exhibited low threshold pressures (<5 kPa) and high rupture pressures (138 kPa – 720 kPa) which suggest safe operation for the DCC application. These results demonstrate that the actuators can achieve forces, displacements, and rise times suitable to assist with cardiac function.

Fatigue life testing of swaged pneumatic artificial muscles as actuators for aerospace applications

2012 ◽  
Vol 23 (3) ◽  
pp. 327-343 ◽  
Author(s):  
Benjamin KS Woods ◽  
Michael F Gentry ◽  
Curt S Kothera ◽  
Norman M Wereley
Keyword(s):  
Fatigue Testing ◽  
Operating Conditions ◽  
Tensile Failure ◽  
Artificial Muscles ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Performance Improvements ◽  
Aerospace Applications ◽  
Pneumatic Artificial Muscles ◽  
Weight Penalty

Pneumatic artificial muscles are a class of pneumatically driven actuators that are remarkable for their simplicity, lightweight, and excellent performance. These actuators are essentially a tubular bladder surrounded by a braided sleeve and sealed at both ends. Pressurization of the actuators generates contraction and tensile forces. Pneumatic artificial muscles have traditionally been used for robotics applications, but there has been recent interest in adapting them to a variety of aerospace actuation applications where their large stroke and force, which are realized at minimal weight penalty, create potential performance improvements over traditional technologies. However, an impediment to wide-spread acceptance of pneumatic artificial muscles is the relatively short fatigue lives of the actuators reported in the literature (typically, less than 18,000 actuation cycles before damage occurs). The purpose of this study is to develop a new construction method designed to greatly increase the number of fatigue cycles before damage occurs. The fabrication methodology employs a swaging process to provide smooth and distributed clamping of the bladder and braided sleeve components onto the end fittings. This approach minimizes stress concentrations and provides high mechanical strength, which can be experimentally validated via testing for the ultimate tensile failure load. Finite element analysis was used to refine the design of the swaged end fittings before extensive fatigue testing began. Long-term fatigue testing of the actuators under realistic operating conditions showed a substantial increase in actuator life, from a maximum of less than 18,000 cycles in previous research studies to more than 120,000,000 cycles in this study.

An Experimental Powered Lower Limb Prosthesis Using Proportional Myoelectric Control

2014 ◽  
Vol 8 (2) ◽  
Author(s):  
Stephanie Huang ◽  
Jeffrey P. Wensman ◽  
Daniel P. Ferris
Keyword(s):  
Lower Limb ◽  
Muscle Activity ◽  
Plantar Flexion ◽  
Myoelectric Control ◽  
Artificial Muscles ◽  
Plantar Flexors ◽  
Force Output ◽  
Prosthetic Socket ◽  
Pneumatic Artificial Muscles ◽  
Powered Prosthesis

One way to provide powered lower limb prostheses with greater adaptability to a wearer's intent is to use a neural signal to provide feedforward control of prosthesis mechanics. We designed and tested the feasibility of an experimental powered ankle-foot prosthesis that uses pneumatic artificial muscles and proportional myoelectric control to vary ankle mechanics during walking. The force output of the artificial plantar flexor muscles was directly proportional to the subject's residual gastrocnemius muscle activity. The maximum force generated by a pair of artificial muscles fixed at nominal length was 3513 N. The maximum planter flexion torque that could be generated during walking was 176 Nm. The force bandwidth of the pneumatic artificial muscles was 2 Hz. The electromechanical delay was 33 ms, the time to peak tension was 48 ms, and the half relaxation time was 50 ms. We used two artificial muscles as dorsiflexors and two artificial muscles as plantar flexors. The prosthetic ankle had 25 deg of dorsiflexion and 35 deg of plantar flexion with the artificial muscles uninflated. The intent of the device was not to create a commercially viable prosthesis but to have a laboratory prototype to test principles of locomotor adaptation and biomechanics. We recruited one unilateral transtibial amputee to walk on a treadmill at 1.0 m/s while wearing the powered prosthesis. We recorded muscle activity within the subject's prescribed prosthetic socket using surface electrodes. The controller was active throughout the entire gait cycle and did not rely on detection of gait phases. The amputee subject quickly adapted to the powered prosthesis and walked with a functional gait. The subject generated peak ankle power at push off that was similar between amputated and prosthetic sides. Our results suggest that amputees can use their residual muscles for proportional myoelectric control to alter prosthetic mechanics during walking.

scholarly journals An extended state observer-based full-order sliding mode control for robotic joint actuated by antagonistic pneumatic artificial muscles

2021 ◽  
Vol 18 (1) ◽  
pp. 172988142098603
Author(s):  
Daoxiong Gong ◽  
Mengyao Pei ◽  
Rui He ◽  
Jianjun Yu
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
State Observer ◽  
Extended State Observer ◽  
Artificial Muscles ◽  
Extended State ◽  
Robot System ◽  
Mode Control ◽  
Physical Experiments ◽  
Pneumatic Artificial Muscles

Pneumatic artificial muscles (PAMs) are expected to play an important role in endowing the advanced robot with the compliant manipulation, which is very important for a robot to coexist and cooperate with humans. However, the strong nonlinear characteristics of PAMs hinder its wide application in robots, and therefore, advanced control algorithms are urgently needed for making the best use of the advantages and bypassing the disadvantages of PAMs. In this article, we propose a full-order sliding mode control extended state observer (fSMC-ESO) algorithm that combines the ESO and the fSMC for a robotic joint actuated by a pair of antagonistic PAMs. The fSMC is employed to eliminate the chattering and to guarantee the finite-time convergence, and the ESO is adopted to observe both the total disturbance and the states of the robot system, so that we can inhibit the disturbance and compensate the nonlinearity efficiently. Both simulations and physical experiments are conducted to validate the proposed method. We suggest that the proposed method can be applied to the robotic systems actuated by PAMs and remarkably improve the performance of the robot system.

scholarly journals Muscle-fiber array inspired, multiple-mode, pneumatic artificial muscles through planar design and one-step rolling fabrication

2021 ◽  
Author(s):  
Jiang Zou ◽  
Miao Feng ◽  
Ningyuan Ding ◽  
Peinan Yan ◽  
Haipeng Xu ◽  
...  
Keyword(s):  
Muscle Fiber ◽  
Artificial Muscles ◽  
Fiber Array ◽  
Fiber Arrays ◽  
Multiple Mode ◽  
Pneumatic Artificial Muscles ◽  
Pipe Line ◽  
One Step ◽  
Robotic Applications ◽  
Compliant Electrodes

Abstract Although the advances in artificial muscles enable creating soft robots with biological dexterity and self-adaption in unstructured environments, producing scalable artificial muscles with multiple-mode actuations is still elusive. Inspired by muscle-fiber arrays in muscular hydrostats, we present a class of versatile artificial muscles, called MAIPAMs (Muscle-fiber Array Inspired Pneumatic Artificial Muscles), capable of multiple-mode actuations (such as parallel elongation-bending-spiraling actuations, parallel 10 bending actuations, and cascaded elongation-bending-spiraling actuations). Our MAIPAMs mainly consist of active 3D elastomer-balloon arrays reinforced by a passive elastomer membrane, which is achieved through a planar design and one-step rolling fabrication approach. We introduce the prototypical designs of MAIPAMs and demonstrate their muscle-mimic structures and versatility, as well as their scalable ability to integrate flexible while un-stretchable layers for contraction and twisting actuations and compliant electrodes for self-sensing. We further demonstrate that this class of artificial muscles shows promising potentials for versatile robotic applications, such as carrying a camera for recording videos, gripping and manipulating objects, and climbing a pipe-line.

Variable recruitment in bundles of miniature pneumatic artificial muscles

2016 ◽  
Vol 11 (5) ◽  
pp. 056014 ◽  
Author(s):  
Sylvie A DeLaHunt ◽  
Thomas E Pillsbury ◽  
Norman M Wereley
Keyword(s):  
Artificial Muscles ◽  
Pneumatic Artificial Muscles ◽  
Variable Recruitment

Experimental Validation of Nominal Model Characteristics for Pneumatic Muscle Actuator

2013 ◽  
Vol 460 ◽  
pp. 1-12 ◽  
Author(s):  
Alexander Hošovský ◽  
Kamil Židek
Keyword(s):  
Control System ◽  
Nonlinear Differential Equations ◽  
Model Performance ◽  
Weight Ratio ◽  
Open Loop ◽  
Artificial Muscles ◽  
Pneumatic Actuators ◽  
Intelligent Control System ◽  
Pneumatic Artificial Muscles ◽  
The One

Pneumatic artificial muscles belong to a category of nonconventional pneumatic actuators that are distinctive for their high power/weight ratio, simple construction and low price and maintenance costs. As such, pneumatic artificial muscles represent an alternative type of pneumatic actuator that could replace the traditional ones in certain applications. Due to their specific construction, PAM-based systems have nonlinear characteristics which make it more difficult to design a control system with good performance. In the paper, a gray-box model (basically analytical but with certain experimental parts) of the one degree-of-freedom PAM-based actuator is derived. This model interconnects the description of pneumatic and mechanical part of the system through a set of several nonlinear differential equations and its main purpose is the design of intelligent control system in simulation environment. The model is validated in both open-loop and closed-loop mode using the measurements on real plant and the results confirm that model performance is in good agreement with the performance of real actuator.

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