Dynamic Modeling of Damping Effects in Highly Damped Compliant Fingers for Applications Involving Contacts

Liu, Chih‐Hsing; Lee, Kok Meng

doi:10.1115/1.4005270

Cited by 39 publications

(14 citation statements)

References 12 publications

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“…In contrast to rigid mechanisms and robots that have moduli in the order of 10 9 ∼ 10 12 , soft robots such as soft hands, [28][29][30] soft grippers, 24,31,32 or soft manipulators 33,34 usually have the ability to gently grip and maneuver vulnerable objects. Soft graspers can be used in the handling of delicate food products [35][36][37][38] as most natural food products are variable in shape and easily bruised. 35 Some special gripper designs for harvesting horticulture products such as tomato 39,40 and strawberry 41 are also proposed.…”

Section: Introductionmentioning

confidence: 99%

Topology and Size–Shape Optimization of an Adaptive Compliant Gripper with High Mechanical Advantage for Grasping Irregular Objects

Liu¹,

Chiu²,

Hsu³

et al. 2019

Robotica

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SummaryThis study presents an optimal design procedure including topology optimization and size–shape optimization methods to maximize mechanical advantage (which is defined as the ratio of output force to input force) of the synthesized compliant mechanism. The formulation of the topology optimization method to design compliant mechanisms with multiple output ports is presented. The topology-optimized result is used as the initial design domain for subsequent size–shape optimization process. The proposed optimal design procedure is used to synthesize an adaptive compliant gripper with high mechanical advantage. The proposed gripper is a monolithic two-finger design and is prototyped using silicon rubber. Experimental studies including mechanical advantage test, object grasping test, and payload test are carried out to evaluate the design. The results show that the proposed adaptive complaint gripper assembly can effectively grasp irregular objects up to 2.7 kg.

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Section: Introductionmentioning

confidence: 99%

Topology and Size–Shape Optimization of an Adaptive Compliant Gripper with High Mechanical Advantage for Grasping Irregular Objects

Liu¹,

Chiu²,

Hsu³

et al. 2019

Robotica

Self Cite

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“…On the base of the acceleration in Equation , the displacement fields can be updated using the central difference integration scheme

{bold-italicu}_{t + normalΔ t} = \frac{4}{2 + γ normalΔ t} {bold-italicu}_{t} + \frac{γ normalΔ t - 2}{2 + γ normalΔ t} {bold-italicu}_{t - normalΔ t} + \frac{2 normalΔ t^{2}}{2 + γ normalΔ t} {bold-italica}_{t}

where γ is the mass proportional coefficient in the Rayleigh damping defined as

double-struckC = γ double-struckM + η double-struckK

. The stiffness proportional term

η double-struckK

is insignificant for low‐frequency applications, and thus, η is set to 0 . Herein, the damping is introduced to achieve a equivalent static solution.…”

Section: Smoothed Particle Hydrodynamics Methods For Plane Elastic Strmentioning

confidence: 99%

Topology optimization of plane structures using smoothed particle hydrodynamics method

Lin

Guan

Zhao

et al. 2016

Numerical Meth Engineering

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This paper presents an alternative topology optimization method based on an efficient meshless smoothed particle hydrodynamics (SPH) algorithm. To currently calculate the objective compliance, the deficiencies in standard SPH method are eliminated by introducing corrective smoothed particle method and total Lagrangian formulation. The compliance is established relative to a designed density variable at each SPH particle which is updated by optimality criteria method. Topology optimization is realized by minimizing the compliance using a modified solid isotropic material with penalization approach. Some numerical examples of plane elastic structure are carried out and the results demonstrate the suitability and effectiveness of the proposed SPH method in the topology optimization problem. 727As suggested by Sigmund and Maute [4], non-FE based topology optimization methods should be explored to overcome the difficulties met in FE method. At present, meshless method without mesh connectivity has drawn much attention in various real-world engineering problems [13][14][15] and been developed increasingly for the structural topology optimization due to the simplicity and accuracy. As far as we know, the first research on topology optimization problem was performed by Kim [16] for two-dimensional continuum structures using element-free Galerkin (EFG) method; however, the checker-board phenomenon was not eliminated. EFG is also developed to solve the topology optimization problem undergoing geometrically nonlinear deformations, where the material distribution is described by a independent point-wise density interpolation method [17]. Meshless reproducing kernel method is successfully developed for geometrically nonlinear plane elasticity problems [18]. Li [19] has studied topology-optimization problems of elastic structures based on meshless local Petrov-Galerkin"mixed collocation" method. Luo [20] proposed a new structural topology optimization method using a dual-level point-wise density approximant and the meshless Galerkin weak-forms.Unlike the aforementioned meshless method with weak-forms, smoothed particle hydrodynamics (SPH) method discretizes directly the balance equation in strong form with collocation framework. Moreover, the background virtual cells independent of field nodes are required for Guass quadrature in EFG [16,17,20], reproducing kernel [18], and meshless local Petrov-Galerkin [19], but unnecessary in SPH [21]. These make SPH easier to be understood, simpler to be programmed and faster to be implemented, which contributes to the wild application of SPH in the region of computational fluid mechanics. However, the inconsistency and instability are the intrinsic problems in classical SPH method and limit the application in solid mechanics [21].Firstly, because of the boundary truncation of the support domain, SPH method cannot even ensure C 0 consistency, which decreases the approximation accuracy. Many researchers have devotes a lot to the promotion of the consistency and proposed corrective smoothe...

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“…The damping is defined as α β = + C M K which has been extensively used to reduce the undesirable vibration in an oscillatory system (Adhikari, 2000). The stiffness proportional term β K is insignificant for low-frequency applications, thus this model can be reduced to a single mass proportional term (Liu and Lee, 2012) . However, the explicit methods are only conditionally stable.…”

Section: Time Step and Time Integrationmentioning

confidence: 99%

Geometrically nonlinear analysis of two-dimensional structures using an improved smoothed particle hydrodynamics method

Lin

Naceur

Coutellier

et al. 2015

Engineering Computations

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Purpose – The purpose of this paper is to present an efficient smoothed particle hydrodynamics (SPH) method particularly adapted for the geometrically nonlinear analysis of structures. Design/methodology/approach – In order to resolve the inconsistency phenomenon which systematically occurs in the standard SPH method at the domain’s boundaries of the studied structure, the classical kernel function and its spatial derivatives were modified by the use of Taylor series expansion. The well-known tensile instabilities inherent to the Eulerian SPH formulation were attenuated by the use of the Total Lagrangian Formulation (TLF). Findings – In order to demonstrate the effectiveness of the present improved SPH method, several numerical applications involving geometrically nonlinear behaviors were carried out using the explicit dynamics scheme for the time integration of the PDEs. Comparisons of the obtained results using the present SPH model with analytical reference solutions and with those obtained using ABAQUS finite element (FE) commercial software, show its good accuracy and robustness. Practical implications – An additional application including a multilayered composite structure and involving buckling and delamination was investigated using the present improved SPH model and the results are compared to the FE results, they confirmed both the efficiency and the accuracy of the proposed method. Originality/value – An efficient 2D-continuum SPH model for the geometrically nonlinear analysis of thin and thick structures is proposed. Contrarily to the classical SPH approaches, here the constitutive material relations are used to link naturally the stresses and strains. The Total Lagrangian approach is investigated to alleviate the tensile instabilities problem, allowing at the same time to avoid the updating procedure of the neighboring particles search and therefore reducing CPU usage. The proposed approach is valid for isotropic and multilayered composites structures undergoing large transformations. CPU time savings and better results with the new 2D-continuum SPH formulation compared to the classical continuum SPH. The explicit dynamic scheme was used for time integration allowing a fast resolution algorithm even for highly nonlinear problems.

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Dynamic Modeling of Damping Effects in Highly Damped Compliant Fingers for Applications Involving Contacts

Cited by 39 publications

References 12 publications

Topology and Size–Shape Optimization of an Adaptive Compliant Gripper with High Mechanical Advantage for Grasping Irregular Objects

Topology and Size–Shape Optimization of an Adaptive Compliant Gripper with High Mechanical Advantage for Grasping Irregular Objects

Topology optimization of plane structures using smoothed particle hydrodynamics method

Geometrically nonlinear analysis of two-dimensional structures using an improved smoothed particle hydrodynamics method

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