Force and Hydraulic Displacement Amplification of Fiber Reinforced Soft Actuators

2013 ◽  
Author(s):  
Joshua Bishop-Moser ◽  
Girish Krishnan ◽  
Sridhar Kota
Keyword(s):  
Design Space ◽  
Virtual Work ◽  
Small Subset ◽  
Graphical Representations ◽  
High Power Density ◽  
Fiber Reinforced ◽  
Fluid Displacement ◽  
Fiber Reinforcements ◽  
Mckibben Actuators ◽  
Soft Actuators

Soft robots allow for complex continuum motions and shapes that conform to their environment. Using a fiber-reinforced elastomeric enclosure (FREE) driven by fluid provides a high power density, soft continuum actuator. While the force generation for a small subset of this structure known as McKibben actuators has been studied extensively, the force and moments generated by a wider set of fiber reinforcements have not been previously investigated. Using virtual work and kinematics derived from fiber inextensibility and fluid incompressibility, the force and moments for the entire design space of FREEs has been determined analytically. Graphical representations have been created, providing easy tools for synthesis and analysis of force and moments in all possible FREEs. The hydraulic displacement amplification, or volumetric transduction, of output motion to fluid displacement has also been determined using kinematics; this transduction gives an indication of stiffness of the structure. Graphical representations have also been created, providing a designer with an intuitive understanding of the behavior all FREE topologies.

scholarly journals Modeling and Fabrication of Soft Actuators Based on Fiber-Reinforced Elastomeric Enclosures

Actuators ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 127
Author(s):  
Zhi Chen ◽  
Aicheng Zou ◽  
Zhantian Qin ◽  
Xingguo Han ◽  
Tianming Li ◽  
...  
Keyword(s):  
Virtual Work ◽  
Fiber Reinforced ◽  
Complex Environments ◽  
Manufacturing Method ◽  
Soft Actuator ◽  
Rod Theory ◽  
Cosserat Rod ◽  
Proposed Model ◽  
Soft Actuators ◽  
The Relationship

Unlike rigid actuators, soft actuators can easily adapt to complex environments. Understanding the relationship between the deformation of soft actuators and external factors such as pressure would enable rapid designs based on specific requirements, such as flexible, compliant endoscopes. An effective model is demonstrated that predicts the deformation of a soft actuator based on the virtual work principle and the geometrically exact Cosserat rod theory. The deformation process is analyzed for extension, bending, and twisting modules. A new manufacturing method is then introduced. Through any combination of modules, the soft actuator can have a greater workspace and more dexterity. The proposed model was verified for various fiber-reinforced elastomeric enclosures. There is good agreement between the model analysis and the experimental data, which indicates the effectiveness of the model.

Kinematic Synthesis of Fiber Reinforced Soft Actuators in Parallel Combinations

2012 ◽  
Author(s):  
Joshua Bishop-Moser ◽  
Girish Krishnan ◽  
Charles Kim ◽  
Sridhar Kota
Keyword(s):  
Design Space ◽  
Parallel Kinematics ◽  
Fiber Reinforced ◽  
Kinematic Synthesis ◽  
Pick And Place ◽  
Parallel Configuration ◽  
Soft Actuators ◽  
Free Sets

Complex controlled motions, flexible surfaces, and minimal moving mass all drive the need for soft robots using fiber reinforced elastomer enclosures (FREEs) in a parallel configuration. This paper addresses the challenge of synthesizing a design with desired kinematics, as only small portions of the entire design space have been previously investigated. A systematic characterization of the kinematic freedom, constraint, and actuation directions of all circumferentially and longitudinally repeating fiber topologies is determined. The parallel kinematics is mapped for the combinations of actuators by determining the sets of mobilities necessary in the constituent members for all possible output motions. The kinematics of all possible parallel combinations for pairs and triangular triplets of FREEs are mapped. A graphical user interface (GUI) is presented, which allows a user to input a kinematic specification and generate all feasible FREE sets and their respective kinematics. With the entire design space mapped and easily accessible, a range of possible applications across a span of kinematic requirements becomes readily attainable. A case study is performed to verify the ability of the GUI to determine feasible FREE sets for a pick-and-place manipulator task.

Wear Mechanism of Unidirectionally Oriented Fiber-Reinforced Plastics

1977 ◽  
Vol 99 (4) ◽  
pp. 401-407 ◽  
Author(s):  
T. Tsukizoe ◽  
N. Ohmae
Keyword(s):  
Mechanical Properties ◽  
Carbon Fibers ◽  
Wear Behavior ◽  
High Modulus ◽  
Fiber Reinforced ◽  
Reinforced Plastics ◽  
Sliding Direction ◽  
Oriented Fiber ◽  
Fiber Reinforcements ◽  
Fiber Reinforced Plastics

Wear between unidirectionally oriented fiber-reinforced-plastics and mild steel has been investigated. The wear behavior was found to be greatly influenced by the sliding direction, the mechanical properties of fiber-reinforced-plastics and by the tribological properties of fiber-reinforcements or matrices. A summarization of wear-resistance of seven different kinds of fiber-reinforced-plastics signified that the epoxy resin reinforced with high-modulus carbon fibers was the best wear-resistant fiber-reinforced-plastics.

Realistic and Highly Functional Pediatric Externally Powered Prosthetic Hand Using Pneumatic Soft Actuators

2020 ◽  
Vol 32 (5) ◽  
pp. 1034-1043
Author(s):  
Hironari Taniguchi ◽  
Nobuo Takemoto ◽  
Ren Yakami ◽  
Shuichi Wakimoto ◽  
Takero Oshikawa ◽  
...  
Keyword(s):  
Body Image ◽  
Acrylonitrile Butadiene Styrene ◽  
Human Hand ◽  
Prosthetic Hand ◽  
Early Age ◽  
Flexible Joint ◽  
Human Arm ◽  
Mckibben Actuators ◽  
Soft Actuators ◽  
Butadiene Styrene

It is known that introducing a pediatric externally powered prosthetic hand from an early age has certain merits such as the recovery of body image. However, this process is not popular in Japan. The high cost and technological problems of the hand have resulted in difficulty in its popularization. The pediatric prosthetic hand must be lighter and smaller than the adult one. Furthermore, parents of users prefer a prosthetic hand, such as a human arm and hand. We developed a prosthetic hand that demonstrates certain functionalities and appearances similar to a real human hand. The prosthetic hand consists of miniature McKibben actuators and is manufactured from acrylonitrile-butadiene-styrene resin and covered by a silicon glove. It has flexible joint structures and can grasp objects of various shapes. In this paper, we present a prototype of the pediatric prosthetic hand and the results of gripping experiments, bending and extension of finger experiments, and user tests.

A virtual work model for the design and parameter identification of cylindrical pressure-driven soft actuators

2021 ◽  
pp. 1-16
Author(s):  
Frederik Lamping ◽  
Kristin M. de Payrebrune
Keyword(s):  
Parameter Identification ◽  
Virtual Work ◽  
Fiber Reinforcement ◽  
Material Model ◽  
Geometric Constraints ◽  
Dependent Behavior ◽  
Applied Forces ◽  
Work Model ◽  
Soft Actuators ◽  
Pressure Driven

Abstract In this paper, we derive a model based on the principle of virtual work to describe the deformations of cylindrical pressure-driven soft actuators with four types of fiber reinforcement and with externally applied forces. Such cylindrical actuators are often used as the basis for multi-chamber soft robotic systems, for example bending actuators. In the virtual work model, each type of reinforcement leads to particular geometric constraints; the energy of the stretched material is determined by the Yeoh material model. Finally, the stretch of the actuator is solved numerically by a minimization problem. The virtual work model yielded only little deviations of the predicted stretch relative to Finite Element simulations in Abaqus. The key contribution of the virtual work model is improved parameter identification for the modeling of cylindrical soft actuators, as it illustrates the possibility to distinguish between material-dependent behavior and geometry-dependent behavior of these actuators. Also, the virtual work model is applicable in the design process of the investigated actuators. We demonstrate that an optimization of the actuator's inner and outer radii and of its fiber angle, respectively, is possible and we derive design rules including criteria for the choice of fiber reinforcement.

High-Order Mixture Homogenization of Fiber-Reinforced Composites

1991 ◽  
Vol 113 (4) ◽  
pp. 254-263 ◽  
Author(s):  
A. Toledano ◽  
H. Murakami
Keyword(s):  
Virtual Work ◽  
Constitutive Relations ◽  
Equations Of Motion ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Material Interfaces ◽  
Explicit Finite Element ◽  
Exact Data ◽  
Tangent Moduli

An asymptotic mixture theory of fiber-reinforced composites with periodic microstructure is presented for rate-independent inelastic responses, such as elastoplastic deformation. Key elements are the modeling capability of simulating critical interaction across material interfaces and the inclusion of the kinetic energy of micro-displacements. The construction of the proposed mixture model, which is deterministic, instead of phenomenological, is accomplished by resorting to a variational approach. The principle of virtual work is used for total quantities to derive mixture equations of motion and boundary conditions, while Reissner’s mixed variational principle (1984, 1986), applied to the incremental boundary value problem yields consistent mixture constitutive relations. In order to assess the model accuracy, numerical experiments were conducted for static and dynamic loads. The prediction of the model in the time domain was obtained by an explicit finite element code. DYNA2D is used to furnish numerically exact data for the problems by discretizing the details of the microstructure. On the other hand, the model capability of predicting effective tangent moduli was tested by comparing results with NIKE2D. In all cases, good agreement was observed between the predicted and exact data for plastic, as well as elastic responses.

Fiber-Reinforced Membrane Models of McKibben Actuators

2003 ◽  
Vol 70 (6) ◽  
pp. 853-859 ◽  
Author(s):  
W. Liu ◽  
C. R. Rahn
Keyword(s):  
Axial Load ◽  
Cylindrical Tube ◽  
Longitudinal Axis ◽  
Fiber Reinforced ◽  
Initial Shape ◽  
Fiber Angle ◽  
Inner Pressure ◽  
Membrane Models ◽  
Mckibben Actuators ◽  
Inextensible Fibers

A McKibben actuator consists of an internally pressurized elastic cylindrical tube covered by a shell braided with two families of inextensible fibers woven at equal and opposite angles to the longitudinal axis. Increasing internal pressure causes the actuator to expand radially and, due to the fiber constraint, contract longitudinally. This contraction provides a large force that can be used for robotic actuation. Based on large deformation membrane theory, the actuator is modeled as a fiber-reinforced cylinder with applied inner pressure and axial load. Given the initial shape, material parameters, axial load, and pressure, the analytical model predicts the deformed actuator shape, fiber angle, and fiber and membrane stresses. The analytical results show that for a long and thin actuator the deformed fiber angle approaches 54°44′ at infinite pressure. The actuator elongates and contracts for actuators with initial angles above and below 54°44′ degrees, respectively. For short and thick actuators with initial angles relatively close to 0 deg or 90 deg, however, a fiber angle boundary layer extends to the middle of the actuator, limiting possible extension or contraction. The calculated longitudinal strain and radius change match experimental results to within 5%.

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