scholarly journals Effect of Geometrical Shape on Axial Deformation of Soft Actuator

2021 ◽  
Vol 2115 (1) ◽  
pp. 012047
Author(s):  
Vishal Mehta ◽  
Mihir Chauhan
Keyword(s):  
Geometrical Shape ◽  
Light Weight ◽  
Lateral Deformation ◽  
Axial Deformation ◽  
Element Analysis ◽  
Lateral Direction ◽  
Soft Actuator ◽  
Angular Deflection ◽  
Soft Actuators ◽  
And Control

Abstract Soft actuators are the latest trend of research because of their light weight and ease of manufacturing and control. Soft actuators have expanded their fields and taken place in many applications where linear or angular deflection is required. Soft actuators are very useful in the applications where deflection is required with soft touch. Soft Actuators are highly compliant and adaptive to unknown environments. Because of these characteristics, soft actuators are very popular in the field of medical and in the applications where interaction with fragile structure is required. The soft actuators can give required responses mostly depends on their shape. Linear or angular deformation can be achieved by changing the geometrical shape of actuators. This paper presents the effect of geometrical shape on axial deformation of soft pneumatic actuator. Samples of soft actuators are selected with various shapes for finite element analysis. Results are obtained in form of axial and lateral deformation. An attempt is made to achieve good amount of axial deformation with very less or negligible lateral deformation by selecting appropriate shape. Based on the generated results, the shape is identified which gives desired results and more suitable among the selected nine samples. This sample can be useful in the application having space constraint in lateral direction.

scholarly journals Characterization of Sustainable Robotic Materials and Finite Element Analysis of Soft Actuators Under Biodegradation

2021 ◽  
Vol 8 ◽  
Author(s):  
Toshiaki Nagai ◽  
Ashitaka Kurita ◽  
Jun Shintake
Keyword(s):  
Mechanical Properties ◽  
Biodegradable Materials ◽  
Biodegradable Material ◽  
Element Analysis ◽  
Soft Actuator ◽  
Degradation Rates ◽  
Soft Actuators ◽  
And Control ◽  
Good Agreement

Biodegradability is an important property for soft robots that makes them environmentally friendly. Many biodegradable materials have natural origins, and creating robots using these materials ensures sustainability. Hence, researchers have fabricated biodegradable soft actuators of various materials. During microbial degradation, the mechanical properties of biodegradable materials change; these cause changes in the behaviors of the actuators depending on the progression of degradation, where the outputs do not always remain the same against identical inputs. Therefore, to achieve appropriate operation with biodegradable soft actuators and robots, it is necessary to reflect the changes in the material properties in their design and control. However, there is a lack of insight on how biodegradable actuators change their actuation characteristics and how to identify them. In this study, we build and validate a framework that clarifies changes in the mechanical properties of biodegradable materials; further, it allows prediction of the actuation characteristics of degraded soft actuators through simulations incorporating the properties of the materials as functions of the degradation rates. As a biodegradable material, we use a mixture of gelatin and glycerol, which is fabricated in the form of a pneumatic soft actuator. The experimental results show that the actuation performance of the physical actuator reduces with the progression of biodegradation. The experimental data and simulations are in good agreement (R2 value up to 0.997), thus illustrating the applicability of our framework for designing and controlling biodegradable soft actuators and robots.

Design and Experiments of Pneumatic Soft Actuators

Robotica ◽  
2021 ◽  
pp. 1-10
Author(s):  
Liqiang Guo ◽  
Ke Li ◽  
Guanggui Cheng ◽  
Zhongqiang Zhang ◽  
Chu Xu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Production Line ◽  
Element Analysis ◽  
Soft Actuator ◽  
Flexible Material ◽  
The Future ◽  
Inner Diameter ◽  
Soft Actuators ◽  
Torsion Deformation

SUMMARY The soft actuator is made of superelastic material and embedded flexible material. In this paper, a kind of soft tube was designed and used to assemble two kinds of pneumatic soft actuators. The experiment and finite element analysis are used to comprehensively analyze and describe the bending, elongation, and torsion deformation of the soft actuator. The results show that the two soft actuators have the best actuation performance when the inner diameter of the soft tube is 4 mm. In addition, when the twisting pitch of the torsional actuator is 24 mm, its torsional performance is optimized. Finally, a device that can be used in the production line was assembled by utilizing those soft actuators, and some operation tasks were completed. This experiment provides some insights for the development of soft actuators with more complex motions in the future.

Impact of the Chamber Shape on a Soft Actuator Mechanism to Mimic the Esophageal Swallowing Process

2018 ◽  
Author(s):  
Alberto Caballero-Ruiz ◽  
Juan A. Hernández-Angulo ◽  
Gabriel Ascanio Gasca ◽  
Leticia Vega-Alvarado ◽  
Leopoldo Ruiz-Huerta ◽  
...  
Keyword(s):  
Peristaltic Wave ◽  
Element Analysis ◽  
Soft Actuator ◽  
Integral Number ◽  
Physical Prototype ◽  
Human Esophagus ◽  
The One ◽  
Soft Actuators ◽  
Manufacturing Technologies ◽  
The Impact

A physical prototype of a human esophagus has been developed for reproducing the human swallowing process with the aim of studying various disorders that impair its function as well as for the development of new foods and technologies for their treatment. Several studies related to the peristalsis phenomena have been conducted in recent years by studying the effect of different parameters defining the peristaltic wave. Mathematical models have been developed to investigate the impact of an integral and a non-integral number of waves during the swallowing of food stuff such as jelly, tomato puree, among others. Swallowing through the esophagus has not only been studied numerically but also reported by using a pneumatic soft actuators. In the present work, the development of a soft actuator mechanism to reproduce the peristaltic wave as the one reported by F.J. Chen et. al. 2014 is described. Such a mechanism consists of a rubber structure that contains an array of chambers actuated by pressurized air to generate the peristaltic wave. The final chamber shape was determined after an iterative process, which involves the elastomer properties, different chamber shapes, finite element analysis and image processing. The characterization of the developed peristaltic mechanism was made by correlating a theoretical study of swallowing peristaltic model and the waveform obtained from the X-ray radiography analysis as the mechanism is actuated. As result, the soft actuator mechanism can reproduce a peristaltic waveform with a correlation coefficient near to 0.9 with respect to the mathematical model reported in literature. In addition, the manufacturing process based on additive manufacturing technologies is also presented.

DESIGN AND ANALYSIS OF BENDING MOTION IN SINGLE AND DUAL CHAMBER BELLOWS STRUCTURED SOFT ACTUATORS

2016 ◽  
Vol 78 (6-13) ◽  
Author(s):  
Tariq Rehman ◽  
A. A. M. Faudzi ◽  
Dyah Ekashanti Octorina Dewi ◽  
K. Suzumori ◽  
M. R. M. Razif ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Silicone Rubber ◽  
Soft Robotics ◽  
Dual Chamber ◽  
Element Analysis ◽  
Rubber Material ◽  
Single Chamber ◽  
Soft Actuator ◽  
Soft Actuators

As one of the most important characteristics of soft actuators, bending motion has been widely used in the field of soft robotics to perform different manipulation and tasks. In this study, we design silicone rubber material based soft actuators consisting of single and dual chambers, and a bellows structure. Several models of bellows soft actuators were designed, simulated and analyzed using finite element analysis (FEA) software MARC®, in order to understand the characteristics of bellows structured soft actuator with single and dual chambers and to optimize the performance of bending motion of bellows soft actuators. The results confirm that the bellows structured pneumatic soft actuator model 4 of single chamber and model 5 of dual chamber produces the best bending motion and bending angles.

Non-Linear Finite Element Analysis of Biologically Inspired Robotic Fin Actuated by Soft Actuators

2014 ◽  
Vol 528 ◽  
pp. 272-277 ◽  
Author(s):  
Muhammad Rusydi Muhammad Razif ◽  
Natarajan Elango ◽  
Ili Najaa Aimi Mohd Nordin ◽  
Ahmad Athif Mohd Faudzi
Keyword(s):  
Finite Element ◽  
Wave Motion ◽  
Biologically Inspired ◽  
Element Analysis ◽  
Soft Actuator ◽  
Linear Finite Element ◽  
Pressure Distributions ◽  
Lateral Displacements ◽  
Soft Actuators ◽  
The Right

In this paper, a robotic fin was idealized with three rays, which are serially connected by thin flexible rubber membranes. Each ray consists a two chamber braided soft actuator operated by pneumatic pressure at the maximum of 20 kPa. The bending of the ray is achieved by alternating the supply of air to the chamber. The soft actuator bends to the right when the left chamber is pressurized and moves to the left when the right chamber is pressurized. The propulsive wave motion along the fin is thus achieved by oscillating the rays at the same frequency but in different phases. The finite element (FE) analysis was conducted in MARC®, nonlinear FE software, from which the lateral displacements of the rays and the corresponding effect on the membranes were measured. The wave amplitude of the fin was computed from the simulation results. The wave motion of the robotic fin and its corresponding pressure distributions were also observed and presented.

scholarly journals Characterisation and Control of a Woven Biomimetic Actuator for Wearable Neurorehabilitative Devices

Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 37
Author(s):  
Vaughan Murphy ◽  
Brandon P. R. Edmonds ◽  
Ana Luisa Trejos
Keyword(s):  
Performance Metrics ◽  
Woven Fabric ◽  
Total Force ◽  
Control Methods ◽  
Soft Actuator ◽  
Sewing Thread ◽  
And Control ◽  
Fabric Mesh ◽  
Biomimetic Actuator ◽  
Multiple Units

Twisted coiled actuators (TCAs) are a type of soft actuator made from polymer fibres such as nylon sewing thread. As they provide motion in a compact, lightweight, and flexible package, they provide a solution to the actuation of wearable mechatronic devices for motion assistance. Their limitation is that they provide low total force, requiring them to actuate in parallel with multiple units. Previous literature has shown that the force and stroke production can be improved by incorporating them into fabric meshes. A fabric mesh could also improve the contraction efficiency, strain rate, and user comfort. Therefore, this study focused on measuring these performance metrics for a set of TCAs embedded into a woven fabric mesh. The experimental results show that the stroke of the actuators scaled linearly with the number of activated TCAs, achieving a maximum applied force of 11.28 N, a maximum stroke of 12.23%, and an efficiency of 1.8%. Additionally, two control methods were developed and evaluated, resulting in low overshoot and steady-state error. These results indicate that the designed actuators are viable for use in wearable mechatronic devices, since they can scale to meet different requirements, while being able to be accurately controlled with minimal additional components.

Mandibular deviations in TMD and non-TMD groups related to eye dominance and head posture

2002 ◽  
Vol 25 (2) ◽  
pp. 147-155 ◽  
Author(s):  
N. Pradham ◽  
G. White ◽  
N. Mehta ◽  
A. Forgione
Keyword(s):  
Head Rotation ◽  
Lateral Direction ◽  
Head Posture ◽  
Control Subjects ◽  
Eye Dominance ◽  
Pain Center ◽  
And Control ◽  
Female Subjects

This study was designed to determine whether eye-dominance affects head posture (rotation) and in turn, whether head posture is associated with mandibular frenum midline deviation, in both TMJ and control subjects. Eye dominance was determined using three tests:Porta, Hole, Point tests. Natural head posture was evaluated using the Arthrodial protractor. Mandibular frenum deviation was recorded as left, right or no deviation. Fifty female subjects were included in the study, 25 TMJ patients attending the Gelb Craniomandibular Pain Center and 25 non-TMJ control subjects. The findings indicate that eye dominance and direction of head rotation are strongly associated in both TMJ and control subjects. Further, in TMJ subjects mandibular deviation occurred in greater frequency than in controls and tends to occur in the contra lateral direction of head rotation.

Exact Perturbation for the Vibration of Almost Annular or Circular Plates

1995 ◽  
Author(s):  
R. G. Parker ◽  
C. D. Mote
Keyword(s):  
Circular Domain ◽  
Circular Plates ◽  
Irregular Domain ◽  
Third Order ◽  
Element Analysis ◽  
Shape Deviation ◽  
Arbitrary Boundary ◽  
Boundary Shape ◽  
Circular Domains ◽  
And Control

Abstract Using perturbation analysis, the eigensolutions for plate vibration problems on nearly annular or circular domains are determined. The irregular domain eigensolutions are calculated as perturbations of the corresponding annular or circular domain eigensolutions. These perturbations are determined exactly. The simplicity of these exact solutions allows the perturbation to be carried through third order for distinct unperturbed eigenvalues and through second order for degenerate unperturbed eigenvalues. Furthermore, this simplicity allows the resulting orthonormalized eigenfunctions to be readily incorporated into response, system identification, and control analyses. The clamped, nearly circular plate is studied in detail, and the exact eigensolution perturbations are derived for an arbitrary boundary shape deviation. Rules governing the splitting of degenerate unperturbed eigenvalues at both first and second orders of perturbation are presented. These rules, which apply for arbitrary shape deviation, generalize those obtained in previous works where specific, discrete asymmetries and first order splitting are examined. The eigensolution perturbations and splitting rules reduce to simple, algebraic formulae in the Fourier coefficients of the boundary shape asymmetry. Elliptical plate eigensolutions are calculated and compared to finite element analysis and, for the fundamental eigenvalue, to the exact solution given by Shibaoka (1956).

Multiple Inputs-Single Accumulated Output Mechanism for Soft Linear Actuators

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Kyeong Ho Cho ◽  
Ho Moon Kim ◽  
Youngeun Kim ◽  
Sang Yul Yang ◽  
Hyouk Ryeol Choi
Keyword(s):  
Artificial Muscle ◽  
Operating Mode ◽  
Robotic Arm ◽  
Soft Actuator ◽  
Wearable Robots ◽  
Working Principle ◽  
Linear Actuators ◽  
Soft Actuators ◽  
Muscle Actuators ◽  
Further Development

Soft linear actuators (SLAs) such as shape memory alloy (SMA) wires, pneumatic soft actuators, dielectric elastomer actuator, and twisted and coiled soft actuator (TCA) called artificial muscle actuators in general, have many advantages over the conventional actuators. SLAs can realize innovative robotic technologies like soft robots, wearable robots, and bionic arms in the future, but further development is still needed in real applications because most SLAs do not provide large displacement or force as needed. This paper presents a novel mechanism supplementing SLAs by accumulating the displacement of multiple SLAs. It adopts the principle of differential gears in reverse. Since the input units of the mechanism are extensible, more displacement can be accumulated by increasing the number of the input units as many as needed. The mechanism is basically used to accumulate displacements, but can be used to accumulate forces by changing its operating mode. This paper introduces the design and working principle of the mechanism and validates its operation experimentally. In addition, the mechanism is implemented on a robotic arm and its effectiveness is confirmed.

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