scholarly journals Modelling and implementation of soft bio-mimetic turtle using echo state network and soft pneumatic actuators

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
MennaAllah Soliman ◽  
Mostafa A. Mousa ◽  
Mahmood A. Saleh ◽  
Mahmoud Elsamanty ◽  
Ahmed G. Radwan
Keyword(s):  
Orientation Angle ◽  
Motion Path ◽  
Echo State Network ◽  
Element Analysis ◽  
Pneumatic Actuators ◽  
Large Pressure ◽  
Inclination Angles ◽  
Maximum Root ◽  
Soft Actuators ◽  
Rotation Motion

AbstractAdvances of soft robotics enabled better mimicking of biological creatures and closer realization of animals’ motion in the robotics field. The biological creature’s movement has morphology and flexibility that is problematic deportation to a bio-inspired robot. This paper aims to study the ability to mimic turtle motion using a soft pneumatic actuator (SPA) as a turtle flipper limb. SPA’s behavior is simulated using finite element analysis to design turtle flipper at 22 different geometrical configurations, and the simulations are conducted on a large pressure range (0.11–0.4 Mpa). The simulation results are validated using vision feedback with respect to varying the air pillow orientation angle. Consequently, four SPAs with different inclination angles are selected to build a bio-mimetic turtle, which is tested at two different driving configurations. The nonlinear dynamics of soft actuators, which is challenging to model the motion using traditional modeling techniques affect the turtle’s motion. Conclusively, according to kinematics behavior, the turtle motion path is modeled using the Echo State Network (ESN) method, one of the reservoir computing techniques. The ESN models the turtle path with respect to the actuators’ rotation motion angle with maximum root-mean-square error of $$1.04 \times 10^{-11}$$ 1.04 × 10 - 11 . The turtle is designed to enhance the robot interaction with living creatures by mimicking their limbs’ flexibility and the way of their motion.

scholarly journals Rapid Design and Analysis of Microtube Pneumatic Actuators Using Line-Segment and Multi-Segment Euler–Bernoulli Beam Models

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 780 ◽  
Author(s):  
Myunggi Ji ◽  
Qiang Li ◽  
In Ho Cho ◽  
Jaeyoun Kim
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Line Segment ◽  
Beam Model ◽  
Element Analysis ◽  
Pneumatic Actuators ◽  
Design And Optimization ◽  
Rapid Design ◽  
The Finite Element Analysis ◽  
Soft Actuators

Soft material-based pneumatic microtube actuators are attracting intense interest, since their bending motion is potentially useful for the safe manipulation of delicate biological objects. To increase their utility in biomedicine, researchers have begun to apply shape-engineering to the microtubes to diversify their bending patterns. However, design and analysis of such microtube actuators are challenging in general, due to their continuum natures and small dimensions. In this paper, we establish two methods for rapid design, analysis, and optimization of such complex, shape-engineered microtube actuators that are based on the line-segment model and the multi-segment Euler–Bernoulli’s beam model, respectively, and are less computation-intensive than the more conventional method based on finite element analysis. To validate the models, we first realized multi-segment microtube actuators physically, then compared their experimentally observed motions against those obtained from the models. We obtained good agreements between the three sets of results with their maximum bending-angle errors falling within ±11%. In terms of computational efficiency, our models decreased the simulation time significantly, down to a few seconds, in contrast with the finite element analysis that sometimes can take hours. The models reported in this paper exhibit great potential for rapid and facile design and optimization of shape-engineered soft actuators.

Buckling characteristics of cut-out borne composite stiffened hyperbolic paraboloid shell panel

2021 ◽  
pp. 146442072110058
Author(s):  
Sarmila Sahoo
Keyword(s):  
Finite Element ◽  
Orientation Angle ◽  
Buckling Load ◽  
Benchmark Problems ◽  
Hyperbolic Paraboloid ◽  
Element Analysis ◽  
Load Effect ◽  
Global Buckling ◽  
Fiber Orientation Angle ◽  
Shell Panel

The present study investigates buckling characteristics of cut-out borne stiffened hyperbolic paraboloid shell panel made of laminated composites using finite element analysis to evaluate the governing differential equations of global buckling of the structure. The finite element code is validated by solving benchmark problems from literature. Different parametric variations are studied to find the optimum panel buckling load. Laminations, boundary conditions, depth of stiffener and arrangement of stiffeners are found to influence the panel buckling load. Effect of different parameters like cut-out size, shell width to thickness ratio, degree of orthotropy and fiber orientation angle of the composite layers on buckling load are also studied. Parametric and comparative studies are conducted to analyze the buckling strength of composite hyperbolic paraboloid shell panel with cut-out.

Valveless microliter combustion for densely packed arrays of powerful soft actuators

2021 ◽  
Vol 118 (39) ◽  
pp. e2106553118
Author(s):  
Ronald H. Heisser ◽  
Cameron A. Aubin ◽  
Ofek Peretz ◽  
Nicholas Kincaid ◽  
Hyeon Seok An ◽  
...  
Keyword(s):  
Tactile Stimulation ◽  
Exothermic Reaction ◽  
Tactile Display ◽  
Metal Electrodes ◽  
Pneumatic Actuators ◽  
Display Technology ◽  
Fluidic Actuators ◽  
Operational Frequency ◽  
Soft Actuators ◽  
Flame Behavior

Existing tactile stimulation technologies powered by small actuators offer low-resolution stimuli compared to the enormous mechanoreceptor density of human skin. Arrays of soft pneumatic actuators initially show promise as small-resolution (1- to 3-mm diameter), highly conformable tactile display strategies yet ultimately fail because of their need for valves bulkier than the actuators themselves. In this paper, we demonstrate an array of individually addressable, soft fluidic actuators that operate without electromechanical valves. We achieve this by using microscale combustion and localized thermal flame quenching. Precisely, liquid metal electrodes produce sparks to ignite fuel lean methane–oxygen mixtures in a 5-mm diameter, 2-mm tall silicone cylinder. The exothermic reaction quickly pressurizes the cylinder, displacing a silicone membrane up to 6 mm in under 1 ms. This device has an estimated free-inflation instantaneous stroke power of 3 W. The maximum reported operational frequency of these cylinders is 1.2 kHz with average displacements of ∼100 µm. We demonstrate that, at these small scales, the wall-quenching flame behavior also allows operation of a 3 × 3 array of 3-mm diameter cylinders with 4-mm pitch. Though we primarily present our device as a tactile display technology, it is a platform microactuator technology with application beyond this one.

Evaluation of a Suitable Material for Soft Actuator Through Experiments and FE Simulations

2022 ◽  
pp. 339-353
Author(s):  
Elango Natarajan ◽  
Muhammad Rusydi Muhammad Razif ◽  
AAM Faudzi ◽  
Palanikumar K.
Keyword(s):  
Tensile Modulus ◽  
Cylindrical Tube ◽  
Fast Response ◽  
Nonlinear Material ◽  
Element Analysis ◽  
Elongation At Break ◽  
Multi Wall Carbon Nanotubes ◽  
Suitable Material ◽  
The Finite Element Analysis ◽  
Soft Actuators

Soft actuators are generally built to achieve extension, contraction, curling, or bending motions needed for robotic or medical applications. It is prepared with a cylindrical tube, braided with fibers that restrict the radial motion and produce the extension, contraction, or bending. The actuation is achieved through the input of compressed air with a different pressure. The stiffness of the materials controls the magnitude of the actuation. In the present study, Silastic-P1 silicone RTV and multi-wall carbon nanotubes (MWCNT) with reinforced silicone are considered for the evaluation. The dumbbell samples are prepared from both materials as per ASTM D412-06a (ISO 37) standard and their corresponding tensile strength, elongation at break, and tensile modulus are measured. The Ogden nonlinear material constants of respective materials are estimated and used further in the finite element analysis of extension, contraction, and bending soft actuators. It is observed that silicone RTV is better in high strain and fast response, whereas, silicone/MWCNT is better at achieving high actuation.

A soft ring oscillator

2019 ◽  
Vol 4 (31) ◽  
pp. eaaw5496 ◽  
Author(s):  
Daniel J. Preston ◽  
Haihui Joy Jiang ◽  
Vanessa Sanchez ◽  
Philipp Rothemund ◽  
Jeff Rawson ◽  
...  
Keyword(s):  
Constant Pressure ◽  
Particle Separation ◽  
Schmitt Trigger ◽  
Ring Oscillator ◽  
System Level ◽  
Pressure Source ◽  
Pneumatic Actuators ◽  
System Parameters ◽  
Soft Actuators ◽  
Single Constant

Periodic actuation of multiple soft, pneumatic actuators requires coordinated function of multiple, separate components. This work demonstrates a soft, pneumatic ring oscillator that induces temporally coordinated periodic motion in soft actuators using a single, constant-pressure source, without hard valves or electronic controls. The fundamental unit of this ring oscillator is a soft, pneumatic inverter (an inverting Schmitt trigger) that switches between its two states (“on” and “off”) using two instabilities in elastomeric structures: buckling of internal tubing and snap-through of a hemispherical membrane. An odd number of these inverters connected in a loop produces the same number of periodically oscillating outputs, resulting from a third, system-level instability; the frequency of oscillation depends on three system parameters that can be adjusted. These oscillatory output pressures enable several applications, including undulating and rolling motions in soft robots, size-based particle separation, pneumatic mechanotherapy, and metering of fluids. The soft ring oscillator eliminates the need for hard valves and electronic controls in these applications.

scholarly journals Study on the Impact Resistance of Metal Flexible Net to Rock fall

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Gaosheng Wang ◽  
Yunhou Sun ◽  
Ao Zhang ◽  
Lei Zheng ◽  
Yuzheng Lv ◽  
...  
Keyword(s):  
Finite Element ◽  
Impact Force ◽  
Impact Resistance ◽  
Time History ◽  
Rock Fall ◽  
Fe Model ◽  
Element Analysis ◽  
Inclination Angles ◽  
Fall Protection ◽  
The Impact

Based on experiments and finite element analysis, the impact resistance of metal flexible net was studied, which can provide reference for the application of metal flexible net in rock fall protection. The oblique (30 degrees) impact experiment of metal flexible net was carried out, the corresponding finite element (FE) to the experiment was established, and the FE model was verified by simulation results to the experimental tests from three aspects: the deformation characteristics of metal flexible net, the time history curves of impact force on supporting ropes, and the maximum instantaneous impact force on supporting ropes. The FE models of metal flexible nets with inclination angles of 0, 15, 30, 45, 60, and 75 degrees were established, and the impact resistance of metal flexible nets with different inclination angles was analyzed. The research shows that the metal flexible net with proper inclination can bounce the impact rock fall out of the safe area and prevent rock fall falling on the metal flexible net, thus realizing the self-cleaning function. When the inclination angle of the metal flexible net is 15, 30, and 45 degrees, respectively, the bounce effect after impact is better, the remaining height is improved, the protection width is improved obviously, and the impact force is reduced. Herein, the impact force of rock fall decreases most obviously at 45 degrees inclination, and the protective performance is relatively good.

Torsional Stiffness Improvement of a Soft Pneumatic Finger Using Embedded Skeleton

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Amin Lotfiani ◽  
Huichan Zhao ◽  
Zhufeng Shao ◽  
Xili Yi
Keyword(s):  
Torsional Stiffness ◽  
Good Precision ◽  
Pneumatic Actuators ◽  
Finite Element Approach ◽  
Grasping And Manipulation ◽  
Element Approach ◽  
Series Of Experiments ◽  
Soft Actuators ◽  
Compact Design ◽  
Rigid Skeleton

Abstract Silicone-based pneumatic actuators are among the most widely used soft actuators in adaptable fingers. However, due to the soft nature of silicone, the performance of these fingers is highly affected by the low torsional stiffness, which may cause failure in grasping and manipulation. To address this problem, a compact design is proposed by embedding a rigid skeleton into a soft pneumatic finger. A finite element approach with an analysical model is used to evaluate the performance of the fingers both with and without the skeleton. Then, a series of experiments is performed to study the bending motion and rigidity of the fingers. The results reveal that the skeleton increases the torsional stiffness of the finger up to 300%. Furthermore, the consistency with the experimental data indicates the good precision of the proposed modeling method. Finally, a two-finger hand is designed to evaluate the performance of the reinforced finger in reality. The grasp experiments illustrate that the hybrid finger with the skeleton is highly adaptable and can successfully grasp and manipulate heavy objects. Thus, a potential approach is proposed to improve the torsional stiffness of silicone-based pneumatic fingers while maintaining adaptability.

Evaluation of a Suitable Material for Soft Actuator Through Experiments and FE Simulations

2020 ◽  
Vol 10 (2) ◽  
pp. 64-76
Author(s):  
Elango Natarajan ◽  
Muhammad Rusydi Muhammad Razif ◽  
AAM Faudzi ◽  
Palanikumar K.
Keyword(s):  
Tensile Modulus ◽  
Cylindrical Tube ◽  
Fast Response ◽  
Nonlinear Material ◽  
Element Analysis ◽  
Elongation At Break ◽  
Multi Wall Carbon Nanotubes ◽  
Suitable Material ◽  
The Finite Element Analysis ◽  
Soft Actuators

Soft actuators are generally built to achieve extension, contraction, curling, or bending motions needed for robotic or medical applications. It is prepared with a cylindrical tube, braided with fibers that restrict the radial motion and produce the extension, contraction, or bending. The actuation is achieved through the input of compressed air with a different pressure. The stiffness of the materials controls the magnitude of the actuation. In the present study, Silastic-P1 silicone RTV and multi-wall carbon nanotubes (MWCNT) with reinforced silicone are considered for the evaluation. The dumbbell samples are prepared from both materials as per ASTM D412-06a (ISO 37) standard and their corresponding tensile strength, elongation at break, and tensile modulus are measured. The Ogden nonlinear material constants of respective materials are estimated and used further in the finite element analysis of extension, contraction, and bending soft actuators. It is observed that silicone RTV is better in high strain and fast response, whereas, silicone/MWCNT is better at achieving high actuation.

Prototype Development of a Parallel-Link Robot Actuated by Pneumatic Linear Drives with Variable Inclination Mechanisms

2014 ◽  
Vol 8 (2) ◽  
pp. 169-176 ◽  
Author(s):  
Takahiro Kosaki ◽  
◽  
Yoshihiro Morinaga ◽  
Manabu Sano ◽  
Keyword(s):  
Low Cost ◽  
Experimental Investigations ◽  
Serial Link ◽  
End Effector ◽  
Pneumatic Actuators ◽  
Prototype Development ◽  
Parallel Arrangement ◽  
Inclination Angles ◽  
Parallel Link

Parallel-link robots are generally high in power and precision because of their parallel arrangement of actuators. However, they have a workspace smaller than that of serial-link robots. In this paper, we develop a parallel-link robot prototype with pneumatic linear drives in which a mechanism for varying the actuator inclination is incorporated to enlarge the workspace. Our parallel-link robot realizes the rotational and translational motions of the end effector principally by means of the linear reciprocating motions of pneumatic linear drives mounted on the base. Auxiliary pneumatic actuators are used to adjust the inclination angles of those main pneumatic linear drives. The use of pneumatic actuators to realize the proposed parallel-link robot results in a lightweight, compact, and low-cost construction. The workspace and motion transmissibility of our parallel-link robot are analyzed through simulations based on kinematics; then, experimental investigations are carried out using the prototype.

The effects of cutouts on buckling behavior of composite plates

2012 ◽  
Vol 19 (3) ◽  
pp. 323-330 ◽  
Author(s):  
Ahmet Erkliğ ◽  
Eyüp Yeter
Keyword(s):  
Fiber Orientation ◽  
Polymer Matrix Composites ◽  
Orientation Angle ◽  
Composite Plates ◽  
Buckling Load ◽  
Matrix Composites ◽  
Element Analysis ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Fiber Orientation Angle

AbstractCutouts such as circular, rectangular, square, elliptical, and triangular shapes are generally used in composite plates as access ports for mechanical and electrical systems, for damage inspection, to serve as doors and windows, and sometimes to reduce the overall weight of the structure. This paper addresses the effects of different cutouts on the buckling behavior of plates made of polymer matrix composites. To study the effects of cutouts on buckling, loaded edges are taken as fixed and unloaded edges are taken as free. Finite element analysis is also performed to predict the effects of different geometrical cutouts, orientations, and position of cutouts on the buckling behavior. The results show that fiber orientation angle and cutout sizes are the most important parameters on the buckling loads. For all types of cutouts the buckling loads decrease dramatically by increasing the fiber orientation angle. It is observed that minimum buckling load is reached when 45° fiber angle is used, and after this angle critical buckling load begins to increase. Also, it is concluded that while fiber orientation angle is 0°, elliptical cutout has the highest buckling load and while fiber orientation angle is 45°, circular cutout has the highest buckling load.

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