Contractile Pneumatic Artificial Muscle Configured to Generate Extension

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Benjamin K. S. Woods ◽  
Shane M. Boyer ◽  
Erica G. Hocking ◽  
Norman M. Wereley ◽  
Curt S. Kothera
Keyword(s):  
Compressive Loading ◽  
Compressive Force ◽  
Artificial Muscle ◽  
Specific Power ◽  
Artificial Muscles ◽  
Specific Work ◽  
Operational Characteristics ◽  
Pneumatic Artificial Muscles ◽  
High Specific Power ◽  
Internal Mechanism

Pneumatic artificial muscles (PAMs) are comprised of an elastomeric bladder surrounded by a braided mesh sleeve. When the bladder is inflated, the actuator may either contract or extend axially, with the direction of motion dependent on the orientation of the fibers in the braided sleeve. Contractile PAMs have excellent actuation characteristics, including high specific power, specific work, and power density. Unfortunately, extensile PAMs exhibit much reduced blocked force, and are prone to buckling under axial compressive loading. For applications in which extensile motion and compressive force are desired, the push-PAM actuator introduced here exploits the operational characteristics of a contractile PAM, but changes the direction of motion and force by employing a simple internal mechanism using no gears or pulleys. Quasi-static behavior of the push-PAM was compared to a contractile PAM for a range of operating pressures. Based on these data, the push-PAM actuator can achieve force and stroke comparable to a contractile PAM tested under the same conditions.

Miniaturized Pneumatic Artificial Muscles Actuating a Bio-Inspired Robot Hand

2013 ◽  
Author(s):  
Thomas E. Pillsbury ◽  
Ryan M. Robinson ◽  
Norman M. Wereley
Keyword(s):  
Degrees Of Freedom ◽  
Full Scale ◽  
Constitutive Relationship ◽  
Force Density ◽  
Human Hand ◽  
Artificial Muscles ◽  
Specific Work ◽  
Robotic Hand ◽  
Robot Hand ◽  
Pneumatic Artificial Muscles

Pneumatic artificial muscles (PAMs) are used in robotics applications for their light-weight design and superior static performance. Additional PAM benefits are high specific work, high force density, simple design, and long fatigue life. Previous use of PAMs in robotics research has focused on using “large,” full-scale PAMs as actuators. Large PAMs work well for applications with large working volumes that require high force and torque outputs, such as robotic arms. However, in the case of a compact robotic hand, a large number of degrees of freedom are required. A human hand has 35 muscles, so for similar functionality, a robot hand needs a similar number of actuators that must fit in a small volume. Therefore, using full scale PAMs to actuate a robot hand requires a large volume which for robotics and prosthetics applications is not feasible, and smaller actuators, such as miniature PAMs, must be used. In order to develop a miniature PAM capable of producing the forces and contractions needed in a robotic hand, different braid and bladder material combinations were characterized to determine the load stroke profiles. Through this characterization, miniature PAMs were shown to have comparably high force density with the benefit of reduced actuator volume when compared to full scale PAMs. Testing also showed that braid-bladder interactions have an important effect at this scale, which cannot be modeled sufficiently using existing methods without resorting to a higher-order constitutive relationship. Due to the model inaccuracies and the limited selection of commercially available materials at this scale, custom molded bladders were created. PAMs created with these thin, soft bladders exhibited greatly improved performance.

scholarly journals Design and Control of a 1-DOF Robotic Lower-Limb System Driven by Novel Single Pneumatic Artificial Muscle

2019 ◽  
Vol 10 (1) ◽  
pp. 43 ◽  
Author(s):  
Tsung-Chin Tsai ◽  
Mao-Hsiung Chiang
Keyword(s):  
Lower Limb ◽  
Artificial Muscle ◽  
Robotic System ◽  
Artificial Muscles ◽  
Prototype System ◽  
Pneumatic Artificial Muscle ◽  
Torsion Spring ◽  
Pneumatic Artificial Muscles ◽  
Control Response ◽  
Spring Mechanism

This study determines the practicality and feasibility of the application of pneumatic artificial muscles (PAMs) in a pneumatic therapy robotic system. The novel mechanism consists of a single actuated pneumatic artificial muscle (single-PAM) robotic lower limb that is driven by only one PAM combined with a torsion spring. Unlike most of previous studies, which used dual-actuated pneumatic artificial muscles (dual-PAMs) to drive joints, this design aims to develop a novel single-PAM for a one degree-of-freedom (1-DOF) robotic lower-limb system with the advantage of a mechanism for developing a multi-axial therapy robotic system. The lower limb robotic assisting system uses the stretching/contraction characteristics of a single-PAM and the torsion spring designed by the mechanism to realize joint position control. The joint is driven by a single-PAM controlled by a proportional pressure valve, a designed 1-DOF lower-limb robotic system, and an experimental prototype system similar to human lower limbs are established. However, the non-linear behavior, high hysteresis, low damping and time-variant characteristics for a PAM with a torsion spring still limits its controllability. In order to control the system, a fuzzy sliding mode controller (FSMC) is used to control the path tracking for the PAM for the first time. This control method prevents approximation errors, disturbances, un-modeled dynamics and ensures positioning performance for the whole system. Consequently, from the various experimental results, the control response designed by the joint torsion spring mechanism can also obtain the control response like the design of the double-PAMs mechanism, which proves that the innovative single-PAM with torsion spring mechanism design in this study can reduce the size of the overall aid mechanism and reduce the manufacturing cost, can also improve the portability and convenience required for the wearable accessory, and is more suitable for the portable rehabilitation aid system architecture.

Model-Based Feedforward Control of a Robotic Manipulator With Pneumatic Artificial Muscles

2012 ◽  
Author(s):  
Ryan M. Robinson ◽  
Norman M. Wereley ◽  
Curt S. Kothera
Keyword(s):  
Control Algorithm ◽  
Controller Design ◽  
Feedforward Control ◽  
Artificial Muscles ◽  
Specific Work ◽  
Pneumatic Actuators ◽  
Precise Control ◽  
Model Based ◽  
Pneumatic Artificial Muscles ◽  
Dynamics Simulations

Pneumatic artificial muscles (PAMs) are lightweight, flexible actuators capable of higher specific work than comparably-sized hydraulic actuators at the same pressure and electric motors. PAMs are composed of an elastomeric bladder surrounded by a helically braided sleeve. Lightweight, compliant actuators are particularly desirable in portable, heavy-lift robotic systems intended for interaction with humans, such as those envisioned for patient assistance in hospitals and battlefield casualty extraction. However, smooth and precise control remains difficult because of nonlinearities in the dynamic response. The objective of this paper is to develop a control algorithm that satisfies accuracy and smooth motion requirements for a two degree-of-freedom manipulator actuated by pneumatic artificial muscles and intended for interaction with humans, such as lifting a human. This control strategy must be capable of responding to large, abrupt variations in payload weight over a high range of motion. In previous work, the authors detailed the design and construction of a proof-of-concept PAM-based manipulator. The present work investigates the feasibility of combining output feedback using proportional-integral-derivative control or fuzzy logic control with model-based feedforward compensation to achieve improved closed-loop performance. The model upon which the controller is based incorporates the internal airflow dynamics, the geometric parameters of the pneumatic actuators, and the arm dynamics. Simulations were performed in order to validate the control algorithm, guide controller design, and predict optimal gains. Using real-time interface software and hardware, the controller was implemented and experimentally tested on the manipulator. Performance was evaluated for several trajectories, and different payload weights. The effect of varying the feedforward gain was also analyzed. Model refinement further improved performance.

Actuation of untethered pneumatic artificial muscles and soft robots using magnetically induced liquid-to-gas phase transitions

2020 ◽  
Vol 5 (41) ◽  
pp. eaaz4239 ◽  
Author(s):  
Seyed M. Mirvakili ◽  
Douglas Sim ◽  
Ian W. Hunter ◽  
Robert Langer
Keyword(s):  
Phase Transition ◽  
Gas Phase ◽  
High Performance ◽  
Artificial Muscle ◽  
Artificial Muscles ◽  
Peak Strain ◽  
Soft Robots ◽  
Robotic Arms ◽  
Actuation Mechanism ◽  
Pneumatic Artificial Muscles

Pneumatic artificial muscles have been widely used in industry because of their simple and relatively high-performance design. The emerging field of soft robotics has also been using pneumatic actuation mechanisms since its formation. However, these actuators/soft robots often require bulky peripheral components to operate. Here, we report a simple mechanism and design for actuating pneumatic artificial muscles and soft robotic grippers without the use of compressors, valves, or pressurized gas tanks. The actuation mechanism involves a magnetically induced liquid-to-gas phase transition of a liquid that assists the formation of pressure inside the artificial muscle. The volumetric expansion in the liquid-to-gas phase transition develops sufficient pressure inside the muscle for mechanical operations. We integrated this actuation mechanism into a McKibben-type artificial muscle and soft robotic arms. The untethered McKibben artificial muscle generated actuation strains of up to 20% (in 10 seconds) with associated work density of 40 kilojoules/meter3, which favorably compares with the peak strain and peak energy density of skeletal muscle. The untethered soft robotic arms demonstrated lifting objects with an input energy supply from only two Li-ion batteries.

Development of a new system for reducing the temperature increase during the positioning of spoilers using pneumatic artificial muscle (PAM)

2020 ◽  
Vol 92 (8) ◽  
pp. 1257-1261
Author(s):  
Mustafa Soylak ◽  
Mustafa Bakır
Keyword(s):  
Temperature Increase ◽  
Low Cost ◽  
Artificial Muscle ◽  
Artificial Muscles ◽  
Content Type ◽  
Air Inlet ◽  
Thermal Changes ◽  
Pneumatic Artificial Muscles ◽  
Regional Temperature ◽  
Control Surfaces

Purpose The usage of pneumatic artificial muscles (PAMs) is becoming increasingly widespread across a variety of industries because of its advantages such as its lightness and its ability to generate a huge amount of force using the fewest components. The purpose of this paper is to develop a piece of hardware to minimize and equally distribute the thermal changes on the surface of a PAM when positioning using PAMs. A classic PAM and a PAM that contains the hardware suggested for tasks, such as the positioning of spoilers decelerating control surfaces for aircrafts, were compared experimentally. Design/methodology/approach Rapid thermal changes were detected in the classic PAM, especially at the tip of the PAM. These thermal changes decrease the positioning sensitivity and reliability, thus shortening life span of the PAMs. A component was developed that could create a circulation of air around the tip of the PAM, preventing the temperature increase caused by still air. It is installed inside the PAM and makes it possible to control the pressurized air volume in crucial areas. Shaped as a perforated metal pipe, the component was embedded inside the PAM and effects of this component were investigated. Findings The experiment results have shown that, thanks to the system that was developed, cool air that comes from outside is able to reach the tip of the PAM every time, thus keeping regional temperature increase to a minimum. The temperature increase in the pressurized air inlet was minimized by creating a circulation of air in the area. Originality/value With this study, the distribution of heat in different areas on PAM was homogenized at a low cost using the component that was developed.

Flexible Sensor for McKibben Pneumatic Artificial Muscle Actuator

2009 ◽  
Vol 3 (6) ◽  
pp. 731-740 ◽  
Author(s):  
Shinji Kuriyama ◽  
◽  
Ming Ding ◽  
Yuichi Kurita ◽  
Jun Ueda ◽  
...  
Keyword(s):  
Artificial Muscle ◽  
The Elderly ◽  
Axial Displacement ◽  
Artificial Muscles ◽  
Pneumatic Artificial Muscle ◽  
Flexible Sensor ◽  
Pneumatic Artificial Muscles ◽  
Circumferential Displacement ◽  
Mckibben Actuators ◽  
Power Assistance

The demand for flexible, lightweight McKibben pneumatic artificial muscles (McKibben actuators) has been increasing for power assistance equipment used for assisting and rehabilitating the elderly. To accurately control this equipment, the length of the actuator should be measured. However, the equipment becomes heavier and less flexible when a rigid sensor, such as a potentiometer or an encoder, is used. The sensor should be flexible in order to take advantage of the favorable properties of the McKibben actuator. The aim of this study is to measure the length of the actuator without loss of its advantages. We propose a method of estimating the length from the circumferential displacement, which can be measured by a sensor made of electroconductive, flexible rubber. Higher accuracy is obtained by measuring the circumferential displacement than by measuring the axial displacement using this sensor. The sensor’s flexibility enables us to accurately control the actuator without any loss of flexibility or increase in weight. Furthermore, the sensor does not require the attachment of any rigid fixtures. The accuracy of the estimate is successfully evaluated and the usefulness of the proposed method is verified through its application to a multi-link arm driven by the McKibben actuator.

Development of Semi-Crouching Assistive Device Using Pneumatic Artificial Muscle

2020 ◽  
Vol 32 (5) ◽  
pp. 885-893
Author(s):  
Naoki Saito ◽  
Daisuke Furukawa ◽  
Toshiyuki Satoh ◽  
Norihiko Saga ◽  
◽  
...  
Keyword(s):  
Weight Ratio ◽  
Artificial Muscle ◽  
Assistive Device ◽  
Artificial Muscles ◽  
Pneumatic Artificial Muscle ◽  
Contraction Force ◽  
Lower Back ◽  
Pneumatic Artificial Muscles ◽  
Compressive Pressure ◽  
Analytical Result

This paper describes a semi-crouching assistive device using pneumatic artificial muscles. The goal of this device is to reduce the load on the lower back when performing work in the semi-crouching position. The load on the lower back is reduced by decreasing the compressive pressure on the lumbar disk of the lower back. This compressive pressure increases as the contraction force of the erector spine increases. Therefore, it is important to reduce the muscle activity of the erector spine. Based on the analytical result of a worker’s position model, the proposed device adopts a scheme to push the chest of the user as an appropriate assistive method. Additionally, the analytical result shows that a reduction in weight of the device is also important for decreasing the load on the lower back. Based on these results, we prototyped a lightweight semi-crouching assistive device that can generate sufficient assistive force via a pneumatic artificial muscle, which has high power to weight ratio. This device was experimentally evaluated via electromyogram of the erector spine when the user maintains a semi-crouching position. The experimental results confirmed the usefulness of this device.

Operating Modes of Pneumatic Artificial Muscle Actuator

2013 ◽  
Vol 308 ◽  
pp. 39-44 ◽  
Author(s):  
Mária Tóthová ◽  
Ján Piteľ ◽  
Jana Boržíková
Keyword(s):  
Position Control ◽  
Artificial Muscle ◽  
Pneumatic Actuator ◽  
Variable Pressure ◽  
Artificial Muscles ◽  
Pneumatic Artificial Muscle ◽  
Operating Modes ◽  
Main Requirement ◽  
Pneumatic Artificial Muscles ◽  
Operation Characteristics

The paper describes operating modes of the PAM based actuator consisting of two pneumatic artificial muscles (PAMs) in antagonistic connection. The artificial muscles are acting against themselves and resultant position of the actuator is given by equilibrium of their forces according to different pressures in muscles. The main requirement for operation of such pneumatic actuator is uniform movement and accurate arm position control according to input desired variable. There are described in paper operation characteristics of the pneumatic artificial muscle in variable pressure and then operation characteristics of the pneumatic artificial muscle actuator consisting of two muscles in antagonistic connection.

scholarly journals Variable Stiffness Structures Utilizing Pneumatic Artificial Muscles

2019 ◽  
Vol 256 ◽  
pp. 01005
Author(s):  
Feng Ning ◽  
Yingli Chang ◽  
Jingze Wang
Keyword(s):  
Artificial Muscle ◽  
Variable Stiffness ◽  
Pressure Control ◽  
Air Pressure ◽  
Homogeneous Distribution ◽  
Artificial Muscles ◽  
Wide Range ◽  
Pneumatic Artificial Muscles ◽  
Spring System

Pneumatic artificial muscles (PAMs) can offer excellent force-to-weight ratios and act as shape-changing actuator under injecting the actuation fluid into their bladders. PAMs could be easily utilized for morphing structures due to their millimeter-scale diameter. The pressurized PAM can serve not only as artificial muscle actuator which obtains contraction deformation capability but also as a spring system with variable stiffness. In this study, the stiffness behaviors of pressurized PAMs and a variable stiffness structure are investigated. By taking advantage of the designed PAMs which was conducted by the non- linear quasi-static model, significant changes in the spring stiffness can be achieved by air pressure control. A case study is presented to explore the potential behavior of a structure with circular permutation PAMs. The structure used in this case consists of sixteen PAMs with circular homogeneous distribution and a circular supporter with sixteen slide way runners. The stiffness of presented structure can vary flexibly in wide range through controlling the air pressure levels and slide deformation respectively.

scholarly journals New twist on artificial muscles

2016 ◽  
Vol 113 (42) ◽  
pp. 11709-11716 ◽  
Author(s):  
Carter S. Haines ◽  
Na Li ◽  
Geoffrey M. Spinks ◽  
Ali E. Aliev ◽  
Jiangtao Di ◽  
...  
Keyword(s):  
Artificial Muscle ◽  
Polymer Fibers ◽  
Artificial Muscles ◽  
Specific Work ◽  
New Class ◽  
Hysteretic Performance ◽  
Potential Applications ◽  
Thermally Actuated ◽  
Sewing Threads ◽  
Response To Temperature

Lightweight artificial muscle fibers that can match the large tensile stroke of natural muscles have been elusive. In particular, low stroke, limited cycle life, and inefficient energy conversion have combined with high cost and hysteretic performance to restrict practical use. In recent years, a new class of artificial muscles, based on highly twisted fibers, has emerged that can deliver more than 2,000 J/kg of specific work during muscle contraction, compared with just 40 J/kg for natural muscle. Thermally actuated muscles made from ordinary polymer fibers can deliver long-life, hysteresis-free tensile strokes of more than 30% and torsional actuation capable of spinning a paddle at speeds of more than 100,000 rpm. In this perspective, we explore the mechanisms and potential applications of present twisted fiber muscles and the future opportunities and challenges for developing twisted muscles having improved cycle rates, efficiencies, and functionality. We also demonstrate artificial muscle sewing threads and textiles and coiled structures that exhibit nearly unlimited actuation strokes. In addition to robotics and prosthetics, future applications include smart textiles that change breathability in response to temperature and moisture and window shutters that automatically open and close to conserve energy.

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