Variable recruitment fluidic artificial muscles: modeling and experiments

Bryant, Matthew; Meller, Michael; Garcia, Ephrahim

doi:10.1088/0964-1726/23/7/074009

Cited by 44 publications

(57 citation statements)

References 8 publications

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“…In contrast to cable driven systems, where a static tendon is repeatedly coiled through an external pulley system, some wearables change shape at the textile level. Fluidic textile actuators accomplish this shape‐change when a textile‐based pouch, [ 16,255 ] or several pouches working in unison, [ 22,256,257 ] are inflated by an external liquid or air source, which may traditionally include an air tank, pump, or compressor. Alternative fluidic power sources have been suggested [ 258 ] and recently used in textile‐based devices.…”

Section: Textile Actuators For Wearable Robotsmentioning

confidence: 99%

Textile Technology for Soft Robotic and Autonomous Garments

Sánchez¹,

Walsh²,

Wood³

2020

Adv Funct Materials

168

123

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Textiles have emerged as a promising class of materials for developing wearable robots that move and feel like everyday clothing. Textiles represent a favorable material platform for wearable robots due to their flexibility, low weight, breathability, and soft hand‐feel. Textiles also offer a unique level of programmability because of their inherent hierarchical nature, enabling researchers to modify and tune properties at several interdependent material scales. With these advantages and capabilities in mind, roboticists have begun to use textiles, not simply as substrates, but as functional components that program actuation and sensing. In parallel, materials scientists are developing new materials that respond to thermal, electrical, and hygroscopic stimuli by leveraging textile structures for function. Although textiles are one of humankind's oldest technologies, materials scientists and roboticists are just beginning to tap into their potential. This review provides a textile‐centric survey of the current state of the art in wearable robotic garments and highlights metrics that will guide materials development. Recent advances in textile materials for robotic components (i.e., as sensors, actuators, and integration components) are described with a focus on how these materials and technologies set the stage for wearable robots programmed at the material level.

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Section: Textile Actuators For Wearable Robotsmentioning

confidence: 99%

Textile Technology for Soft Robotic and Autonomous Garments

Sánchez¹,

Walsh²,

Wood³

2020

Adv Funct Materials

168

123

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“…Actuation based on the deformation of intelligent materials generally includes an ion-exchange polymer metal composite (IPMC), dielectric elastomeric actuator (DEA), shape memory alloy (SMA), or responsive hydrogel. A variable pressure actuator based on a fluid has several advantages over these materials in terms of the output force, power density, and ease of control [124][125][126][127] .…”

Section: Bio-inspired Pressurized Liquids In Robot Actuationmentioning

confidence: 99%

A Review of Biological Fluid Power Systems and Their Potential Bionic Applications

et al. 2019

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Nature has always inspired human achievements in industry, and biomimetics is increasingly being applied in fluid power technology. Arachnida use hydraulic forces, rather than muscle, for leg extensions during locomotion. Many cold-blooded and soft-bodied organisms rely on a hydrostatic skeleton to transmit force, which involves a hydraulic mechanism. Biological hydraulic transmission differs from engineering hydraulic transmission in many aspects, such as in energy transfer and transformation, the movement mode, environmental friendliness, system pressure level, and energy supplement mode. The existence of a hydraulic mechanism in a biological drive requires 3 features: a power source, cavity, and working medium. The power source is similar to a hydraulic pump, and the cavity is similar to a hydraulic cylinder, both of which are necessary for producing deformation. The working medium is similar to a hydraulic fluid. Under these 3 conditions, a biological flow is generated inside or outside the body to meet the needs of a biological drive. This paper reviews the biological organisms that employ hydraulic systems, identifies related studies on these biological hydraulic systems, and summarizes the mechanisms involved in using hydraulic pressure to achieve graceful and agile movements. This in-depth study and exploration of biological hydraulic systems can provide a good reference for solving the challenges of using hydraulic systems, such as increasing the energy efficiency, improving reliability, building smart components and systems, reducing the size and weight of components, reducing the environmental impact of systems, and improving and applying energy storage and redeployment capabilities. This paper also includes a detailed discussion of new ideas and innovative sources for the future development of hydraulic systems. In contrast with the bio-inspired designs used in other engineering fields, very few studies have reported on using bio-inspired methods for hydraulic transmission techniques. The aim of this work is to attract the attention of researchers to help address this gap and to promote the use of biologically-inspired methods to improve engineering fluid power systems.

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“…Although typically used as contractile actuators, modifications to the design have allowed them to be used as extensile or bending actuators [8]. Recent studies have extended the use of the FAM to multi-chambered bundles with variable recruitment functionality [9][10][11][12]. Rather than a single FAM acting in isolation, multiple FAMs are bundled together in parallel connected by rigid end plates to form a single actuator, as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…By adaptively recruiting the number of active MUs to meet the load demand, the bundle has the potential to reduce the losses that arise from throttling down the supply pressure. As a result, the variable recruitment bundle has a higher efficiency over a larger force-strain space than a single actuator with equivalent cross-sectional area [9,10]. In addition, by selecting the size and number of FAMs in a MU for a desired force, the force sensitivity can be controlled, allowing for more precise control of the actuator force.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Resistive Forces and Buckling Behavior in Variable Recruitment Fluidic Artificial Muscle Bundles

2021

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Fluidic artificial muscles (FAMs), also known as McKibben actuators, are a class of fiber-reinforced soft actuators that can be pneumatically or hydraulically pressurized to produce muscle-like contraction and force generation. When multiple FAMs are bundled together in parallel and selectively pressurized, they can act as a multi-chambered actuator with bioinspired variable recruitment capability. The variable recruitment bundle consists of motor units (MUs)—groups of one of more FAMs—that are independently pressurized depending on the force demand, similar to how groups of muscle fibers are sequentially recruited in biological muscles. As the active FAMs contract, the inactive/low-pressure units are compressed, causing them to buckle outward, which increases the spatial envelope of the actuator. Additionally, a FAM compressed past its individual free strain applies a force that opposes the overall force output of active FAMs. In this paper, we propose a model to quantify this resistive force observed in inactive and low-pressure FAMs and study its implications on the performance of a variable recruitment bundle. The resistive force behavior is divided into post-buckling and post-collapse regions and a piecewise model is devised. An empirically-based correction method is proposed to improve the model to fit experimental data. Analysis of a bundle with resistive effects reveals a phenomenon, unique to variable recruitment bundles, defined as free strain gradient reversal.

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Variable recruitment fluidic artificial muscles: modeling and experiments

Cited by 44 publications

References 8 publications

Textile Technology for Soft Robotic and Autonomous Garments

Textile Technology for Soft Robotic and Autonomous Garments

A Review of Biological Fluid Power Systems and Their Potential Bionic Applications

Modeling of Resistive Forces and Buckling Behavior in Variable Recruitment Fluidic Artificial Muscle Bundles

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