Towards a soft pneumatic glove for hand rehabilitation
01 Nov 2013-pp 1512-1517
TL;DR: Preliminary results for the design, development and evaluation of a hand rehabilitation glove fabricated using soft robotic technology and the integration of the actuators to it are described, followed by a qualitative evaluation study.
Abstract: This paper presents preliminary results for the design, development and evaluation of a hand rehabilitation glove fabricated using soft robotic technology. Soft actuators comprised of elastomeric materials with integrated channels that function as pneumatic networks (PneuNets), are designed and geometrically analyzed to produce bending motions that can safely conform with the human finger motion. Bending curvature and force response of these actuators are investigated using geometrical analysis and a finite element model (FEM) prior to fabrication. The fabrication procedure of the chosen actuator is described followed by a series of experiments that mechanically characterize the actuators. The experimental data is compared to results obtained from FEM simulations showing good agreement. Finally, an open-palm glove design and the integration of the actuators to it are described, followed by a qualitative evaluation study.
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TL;DR: It is shown that hydraulic actuations of hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water.
Abstract: Sea animals such as leptocephali develop tissues and organs composed of active transparent hydrogels to achieve agile motions and natural camouflage in water. Hydrogel-based actuators that can imitate the capabilities of leptocephali will enable new applications in diverse fields. However, existing hydrogel actuators, mostly osmotic-driven, are intrinsically low-speed and/or low-force; and their camouflage capabilities have not been explored. Here we show that hydraulic actuations of hydrogels with designed structures and properties can give soft actuators and robots that are high-speed, high-force, and optically and sonically camouflaged in water. The hydrogel actuators and robots can maintain their robustness and functionality over multiple cycles of actuations, owing to the anti-fatigue property of the hydrogel under moderate stresses. We further demonstrate that the agile and transparent hydrogel actuators and robots perform extraordinary functions including swimming, kicking rubber-balls and even catching a live fish in water.
673 citations
TL;DR: This study provides a set of systematic design rules to help the robotics community create soft actuators by understanding how these vary their outputs as a function of input pressure for a number of geometrical parameters.
Abstract: Soft fluidic actuators consisting of elastomeric matrices with embedded flexible materials are of particular interest to the robotics community because they are affordable and can be easily customized to a given application. However, the significant potential of such actuators is currently limited as their design has typically been based on intuition. In this paper, the principle of operation of these actuators is comprehensively analyzed and described through experimentally validated quasi-static analytical and finite-element method models for bending in free space and force generation when in contact with an object. This study provides a set of systematic design rules to help the robotics community create soft actuators by understanding how these vary their outputs as a function of input pressure for a number of geometrical parameters. Additionally, the proposed analytical model is implemented in a controller demonstrating its ability to convert pressure information to bending angle in real time. Such an understanding of soft multimaterial actuators will allow future design concepts to be rapidly iterated and their performance predicted, thus enabling new and innovative applications that produce more complex motions to be explored.
658 citations
Cites background or methods from "Towards a soft pneumatic glove for ..."
...To demonstrate the value of the proposed analytical and FEM models, several physical parameters of the actuator (i.e., length, radius, and wall thickness) were varied to evaluate their influence on bending angle at 90°, 180°, and 360° (i.e., full circle) (see Fig....
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...This technique allowed lens distortion issues to be addressed and measurement accuracy to be enhanced....
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...Finally, it was shown that as the wall thickness increased, air pressure also had to increase to achieve a given bending angle [see Fig....
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TL;DR: The development of an underwater gripper that utilizes soft robotics technology to delicately manipulate and sample fragile species on the deep reef is presented, making it the first use of soft robotics in the deep sea for the nondestructive sampling of benthic fauna.
Abstract: This article presents the development of an underwater gripper that utilizes soft robotics technology to delicately manipulate and sample fragile species on the deep reef. Existing solutions for deep sea robotic manipulation have historically been driven by the oil industry, resulting in destructive interactions with undersea life. Soft material robotics relies on compliant materials that are inherently impedance matched to natural environments and to soft or fragile organisms. We demonstrate design principles for soft robot end effectors, bench-top characterization of their grasping performance, and conclude by describing in situ testing at mesophotic depths. The result is the first use of soft robotics in the deep sea for the nondestructive sampling of benthic fauna.
580 citations
Cites background from "Towards a soft pneumatic glove for ..."
...Soft systems also offer improved safety as these pneumatically and hydraulically actuated soft materials are inherently safe for interfacing with humans and animals because of their natural compliance and back drivability.(21,22) Suzumori conducted some the earliest work on soft robotic grippers, in which he created continuum-style soft actuators that consisted of three parallel, fiber-reinforced elastomeric chambers spaced evenly around a central axis....
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TL;DR: Three viable actuator morphologies composed entirely from soft silicone rubber are explored, and these morphologies are differentiated by their internal channel structure, namely, ribbed, cylindrical, and pleated.
Abstract: This work provides approaches to designing and fabricating soft fluidic elastomer robots. That is, three viable actuator morphologies composed entirely from soft silicone rubber are explored, and these morphologies are differentiated by their internal channel structure, namely, ribbed, cylindrical, and pleated. Additionally, three distinct casting-based fabrication processes are explored: lamination-based casting, retractable-pin-based casting, and lost-wax-based casting. Furthermore, two ways of fabricating a multiple DOF robot are explored: casting the complete robot as a whole and casting single degree of freedom (DOF) segments with subsequent concatenation. We experimentally validate each soft actuator morphology and fabrication process by creating multiple physical soft robot prototypes.
395 citations
Cites background from "Towards a soft pneumatic glove for ..."
...have investigated more elaborate channel designs in order to reduce elastomer strain on the outer layer of the actuator, allowing for higher bending curvatures.(51,52) Additionally, Cianchetti et al....
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TL;DR: The achievements and shortcomings of recent technology in these key areas are evaluated, and this paper concludes with a discussion on the potential impacts of soft manipulators on industry and society.
Abstract: Soft robotics is a growing area of research which utilises the compliance and adaptability of soft structures to develop highly adaptive robotics for soft interactions. One area in which soft robotics has the ability to make significant impact is in the development of soft grippers and manipulators. With an increased requirement for automation, robotics systems are required to perform task in unstructured and not well defined environments; conditions which conventional rigid robotics are not best suited. This requires a paradigm shift in the methods and materials used to develop robots such that they can adapt to and work safely in human environments. One solution to this is soft robotics, which enables soft interactions with the surroundings whilst maintaining the ability to apply significant force. This review paper assess the current materials and methods, actuation methods and sensors which are used in the development of soft manipulators. The achievements and shortcomings of recent technology in these key areas are evaluated, and this paper concludes with a discussion on the potential impacts of soft manipulators on industry and society.
388 citations
Cites methods from "Towards a soft pneumatic glove for ..."
...The technique of channeled mold actuators are known under different names, such as fluidic elastomer actuators (FEA) (Marchese and Rus, 2015), PneuFlex actuators (Deimel and Brock, 2013, 2015), or Pneumatic Networks (Pneu-Nets) (Polygerinos et al., 2013; Mosadegh et al., 2014)....
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References
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TL;DR: This work aims to expand the methods and materials of chemistry and soft-materials science into applications in fully soft robots, and permits solutions of problems in manipulation, locomotion, and navigation, that are different from those used in conventional hard robotics.
Abstract: In areas from assembly of machines to surgery, and from deactivation of improvised explosive devices (IEDs) to unmanned flight, robotics is an important and rapidly growing field of science and technology. It is currently dominated by robots having hard body plans—constructions largely of metal structural elements and conventional joints—and actuated by electrical motors, or pneumatic or hydraulic systems. Handling fragile objects—from the ordinary (fruit) to the important (internal organs)—is a frequent task whose importance is often overlooked and is difficult for conventional hard robots; moving across unknown, irregular, and shifting terrain is also. Soft robots may provide solutions to both of these classes of problems, and to others. Methods of designing and fabricating soft robots are, however, much less developed than those for hard robots. We wish to expand the methods and materials of chemistry and soft-materials science into applications in fully soft robots. A robot is an automatically controlled, programmable machine. The limbs of animals or insects—structures typically based on rigid segments connected by joints with constrained ranges of motion—often serve as models for mobile elements of robots. Although mobile hard robots sometimes have limb-like structures similar to those of animals (an example is “Big Dog” by Boston Robotics), more often, robots use structures not found in organisms—for example, wheels and treads. The robotics community defines “soft robots” as: 1) machines made of soft—often elastomeric—materials, or 2) machines composed of multiple hard-robotic actuators that operate in concert, and demonstrate soft-robot-like properties; here, we consider only the former. Soft animals offer new models for manipulation and mobility not found, or generated only with difficulty and expense, using hard robots. Because materials from which this class of devices will be fabricated will usually be polymers (especially elastomers), they fall into the realm of organic materials science. The use of soft materials allows for continuous deformation. This type of deformation, in turn, enables structures with ranges of motion limited only by the properties of the materials. Soft robots have the potential to exploit types of structures found, for example, in marine organisms, and in non-skeletal parts of land animals. The tentacles of squid, trunks of elephants, and tongues of lizards and mammals are such examples; their structures are muscular hydrostats. Squid and starfish 14] are highly adept locomotors; their modes of movement have not been productively used, and permit solutions of problems in manipulation, locomotion, and navigation, that are different from those used in conventional hard robotics. The prototypical soft actuator—muscle—developed through the course of evolution. There is currently no technology that can replicate the balanced performance of muscle: it is simultaneously strong and fast, and enables a remarkable range of movements (such as those of a tongue). Muscle-like contraction and dilation occur in ionic polymeric gels on changes in the acidity or salinity of a surrounding ionic solution, but actuation in macroscopic structures is masstransport limited, and typically slow. Other electroactive polymers (EAPs) include dielectric elastomers, electrolytically active polymers, polyelectrolyte gels, and gel-metal composites. Pneumatically-driven McKibben-type actuators are among the most highly developed soft actuators, and have existed for more than fifty years; they consist of a bladder covered in a shell of braided, strong, inextensible fibers. These actuators can be fast, and have a length-load dependence similar to that of muscle but possess only one actuation mode—contraction and extension when pressurization changes. They are, in a sense, an analogue to a single muscle fibril ; using them for complex movements requires multiple actuators acting in series or parallel. Pneumaticallydriven flexible microactuators (FMAs) have been shown to be capable of bending, gripping, and manipulating objects. Roboticists have explored scalable methods for gripping and manipulating objects at the micro and nano scales. The use of compliant materials allows grippers to manipulate objects such as fruit with varied geometry. The field of robotics has not yet caught the attention of soft-materials scientists and chemists. Developing new materials, techniques for fabrication, and principles of design will create new types of soft robots. The objective of this work is to demonstrate a type of design that provides a range of behaviors, and that offers chemists a test bed for new materials and methods of fabrication for soft robots. Our designs use embedded pneumatic networks (PneuNets) of channels in elastomers [*] Prof. G. M. Whitesides Wyss Institute for Biologically Inspired Engineering Harvard University, 3 Blackfan Circle, Boston, MA 02115 (USA) Fax: (+ 1)617-495-9857 and Kavli Institute for Bionano Science & Technology 29 Oxford Street, Cambridge MA (USA) E-mail: gwhitesides@gmwgroup.harvard.edu Homepage: http://gmwgroup.harvard.edu/
1,348 citations
"Towards a soft pneumatic glove for ..." refers background or methods in this paper
...The bending actuators presented here are based on the PneuNet principle of operation [11]....
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...Air is often preferred over fluid due to its low viscosity, compressibility, ease of storage, low weight, environmentally benign nature and that it can enable rapid actuation [11]....
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...A related approach is being investigated by the Whitesides group [11] that employs soft pneumatic networks (PneuNets) embedded in elastomers which actuate (bend or curl) the material by air pressurization....
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TL;DR: In this paper, the elastic properties of a rubber were described in terms of a strain energy function which is an infinite power series in the strain invariants I1, I2 and I3.
Abstract: According to Rivlin's Phenomenological Theory of Rubber Elasticity, the elastic properties of a rubber may be described in terms of a strain energy function which is an infinite power series in the strain invariants I1, I2 and I3. The simplest forms of Rivlin's strain energy function are the neo-Hookean, which is obtained by truncating the infinite series to just the first term in I1, and the Mooney-Rivlin, which retains the first terms in I1 and I2. Recently, we proposed a strain energy function which is a cubic in I1. Conceptually, the proposed function is a material model with a shear modulus that varies with deformation. In this paper, we compare the large strain behavior of rubber as predicted by these forms of the strain energy function. The elastic behavior of swollen rubber is also discussed.
1,198 citations
"Towards a soft pneumatic glove for ..." refers methods in this paper
...Due to the hyperelastic nature of the selected silicone, a second order hyperelastic mathematical model, Yeoh model [19], was used to fully describe the compression and extension phases of the material with coefficients C1=0....
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TL;DR: In this article, a hand-wrist robot was used to improve motor function after a stroke, and the authors evaluated the specific effects of therapy effects on brain reorganization, and found significant behavioural gains at the end of treatment.
Abstract: Robots can improve motor status after stroke with certain advantages, but there has been less emphasis to date on robotic developments for the hand The goal of this study was to determine whether a hand-wrist robot would improve motor function, and to evaluate the specificity of therapy effects on brain reorganization Subjects with chronic stroke producing moderate right arm/hand weakness received 3 weeks therapy that emphasized intense active movement repetition as well as attention, speed, force, precision and timing, and included virtual reality games Subjects initiated hand movements If necessary, the robot completed movements, a feature available at all visits for seven of the subjects and at the latter half of visits for six of the subjects Significant behavioural gains were found at end of treatment, for example, in Action Research Arm Test (34 +/- 20 to 38 +/- 19, P< 00005) and arm motor Fugl-Meyer score (45 +/- 10 to 52 +/- 10, P < 00001) Results suggest greater gains for subjects receiving robotic assistance in all sessions as compared to those receiving robotic assistance in half of sessions The grasp task practiced during robotic therapy, when performed during functional MRI, showed increased sensorimotor cortex activation across the period of therapy, while a non-practiced task, supination/pronation, did not A robot-based therapy showed improvements in hand motor function after chronic stroke Reorganization of motor maps during the current therapy was task-specific, a finding useful when considering generalization of rehabilitation therapy
512 citations
Journal Article•
TL;DR: A robot-based therapy showed improvements in hand motor function after chronic stroke, and reorganization of motor maps during the current therapy was task-specific, a finding useful when considering generalization of rehabilitation therapy.
Abstract: Robots can improve motor status after stroke with certain advantages, but there has been less emphasis to date on robotic developments for the hand. The goal of this study was to determine whether a hand-wrist robot would improve motor function, and to evaluate the specificity of therapy effects on brain reorganization. Subjects with chronic stroke producing moderate right arm/hand weakness received 3 weeks therapy that emphasized intense active movement repetition as well as attention, speed, force, precision and timing, and included virtual reality games. Subjects initiated hand movements. If necessary, the robot completed movements, a feature available at all visits for seven of the subjects and at the latter half of visits for six of the subjects. Significant behavioural gains were found at end of treatment, for example, in Action Research Arm Test (34 +/- 20 to 38 +/- 19, P< 0.0005) and arm motor Fugl-Meyer score (45 +/- 10 to 52 +/- 10, P < 0.0001). Results suggest greater gains for subjects receiving robotic assistance in all sessions as compared to those receiving robotic assistance in half of sessions. The grasp task practiced during robotic therapy, when performed during functional MRI, showed increased sensorimotor cortex activation across the period of therapy, while a non-practiced task, supination/pronation, did not. A robot-based therapy showed improvements in hand motor function after chronic stroke. Reorganization of motor maps during the current therapy was task-specific, a finding useful when considering generalization of rehabilitation therapy.
485 citations
"Towards a soft pneumatic glove for ..." refers background in this paper
...Often rehabilitation for improving hand function requires the patient to perform repetitive task practice (RTP), which involves breaking a task down into individual movements and practicing these exercises to improve hand strength, accuracy, and range of motion [1], [2]....
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...These methods, however, are labor intensive and costly due to the required long hours of training with a physical therapist [1]....
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...oss of the ability to move the fingers, whether partial or total, can greatly inhibit activities of daily living and can considerably reduce one’s quality of life [1]....
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01 Sep 1999
TL;DR: The design of a hydraulic damper with fixed orifices, placed in parallel with the McKibben actuator, is proposed to improve the force-velocity performance and simulation results indicate a significant improvement.
Abstract: Reports on the design of a biorobotic actuator. Biological requirements are developed from published reports in the muscle physiology literature whose parameters are extracted and applied in the form of the Hill muscle model. Data from several vertebrate species (rat, frog, cat, and human) are used to evaluate the performance of a McKibben pneumatic actuator. The experimental results show the force-length properties of the actuator are muscle-like, but the force-velocity properties are not. The design of a hydraulic damper with fixed orifices, placed in parallel with the McKibben actuator, is proposed to improve the force-velocity performance. Simulation results of this practical design indicate a significant improvement.
329 citations