A Topology Optimization Method With Constant Volume Fraction During Iterations for Design of Compliant Mechanisms

Liu, Chih‐Hsing; Huang, Guo Feng

doi:10.1115/1.4032812

Cited by 24 publications

(5 citation statements)

References 18 publications

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“…A prespecified value for volume fraction, which is defined as the calculated volume divided by the full volume of the analysis domain, is used as the constraint in the topology optimization process. In topology synthesis of compliant mechanisms, [13][14][15][16][17][18][19][20][21][22] the usage of numerical springs located at the desired input and output ports of the analyzed compliant mechanism is one general method to specify the input and output locations. Due to the presence of the input and output springs in the analysis domain, the calculated nodal displacements are extremely small; thus, linear elastic finite element formulation is valid in the topology optimization process.…”

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

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“…Topology optimization is a numerical method that can optimize the material layout within a given design domain. It has been used to synthesize various designs, such as soft fingers and grippers [5][6][7][26][27][28][29], constant-force mechanisms [22,23,33], and compliant inverters [34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Topology Optimization Design and Experiment of a Soft Pneumatic Bending Actuator for Grasping Applications

Liu

Chen

Chi

et al. 2022

IEEE Robot. Autom. Lett.

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Soft pneumatic bending actuators are commonly used in robotic grasping applications and can be applied for handling both delicate and irregularly shaped objects. Because these soft pneumatic actuators are typically embedded with multiple air chambers inside soft, thin structures, their maximum payloads are usually low compared to rigid designs of similar size. This article presents a soft pneumatic bending actuator design using a topology optimization procedure that can maximize the bending capability and thus increase the allowable payload of soft grippers that consist of multiple pneumatic bending actuators. After an optimum design is obtained, multiple identical actuators are prototyped through a molding process using a silicone rubber material. Both two-fingered and three-fingered soft grippers are developed using the topology-optimized pneumatic bending actuators. Experiments, including a bending angle test, an output force test, and a payload test, are conducted in this study, and the results are compared against the test results of the commercial SRT soft pneumatic actuator. The experimental results show that the bending angle for the developed bending actuator is 111 degrees on average of 10 tests at an input pressure of 50 kPa. The output force is 9.45 N at an input pressure of 80 kPa, while the maximum payloads of the two-fingered and three-fingered grippers are 2.66kg and 5.12kg, respectively.

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“…Topology optimization is a numerical method to optimize the material layout within a given design domain and is one major approach to synthesize compliant mechanisms. [23][24][25][26][27][28][29] Unlike traditional rigid body mechanisms, compliant mechanisms transform the displacement and force at least partly through the deformation of their structural components, which can offer a great reduction in friction, lubrication, and assemblage. 29 The algorithms of topology optimization methods are extensively investigated in the literature over the past several decades [29][30][31][32][33] and have been used in developing various soft robotic grippers.…”

Section: Introductionmentioning

confidence: 99%

Topology Optimization and Prototype of a Multimaterial-Like Compliant Finger by Varying the Infill Density in 3D Printing

Liu

Yang

2022

Soft Robotics

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This study presents a multimaterial topology optimization method for design of multimaterial compliant mechanisms. Traditionally, the objective function in topology optimization for design of structures is to minimize the strain energy (SE). For synthesis of compliant mechanisms, the objective function is usually to maximize the mutual potential energy (MPE). To design an adaptive compliant gripper for grasping size-varied objects, a multicriteria objective function considering both the SE and MPE at two different output ports is proposed in this study. In addition, based on the fact that different infill densities in three-dimensional (3D) printing leads to prototypes with different equivalent mechanical properties, this article proposes that a multimaterial design can be approximated by varying the values of infill densities in different portions of a 3D-printed component, which enables the multimaterial designs to be prototyped using the general low-cost, single-material fused deposition modeling 3D printing machines. The proposed method is used to design and prototype a bi-material compliant finger which is 3D printed using a flexible thermoplastic elastomer with infill densities of 30% and 100%. The experimental results demonstrate that the bi-material finger is a better design in terms of reducing the driving force while increasing the output displacement at the fingertip comparing to the single-material finger design with the same volume and weight. Furthermore, a two-finger gripper with two identical multimaterial-like compliant fingers is prototyped and installed on a six-axis industrial robot. The experimental tests are performed to demonstrate the effectiveness of the presented design.

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A Topology Optimization Method With Constant Volume Fraction During Iterations for Design of Compliant Mechanisms

Cited by 24 publications

References 18 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 Design and Experiment of a Soft Pneumatic Bending Actuator for Grasping Applications

Topology Optimization and Prototype of a Multimaterial-Like Compliant Finger by Varying the Infill Density in 3D Printing

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