On understanding of design problem formulation for compliant mechanisms through topology optimization

Cao, Lin; Dolovich, Allan T.; Zhang, W. J.

doi:10.5194/ms-4-357-2013

Cited by 24 publications

(7 citation statements)

References 36 publications

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“…Meanwhile, dual FBGs temperature compensation will be conducted to offset the cross influence of temperature. To improve resolution and accuracy, various types of epoxy will be explored, and optimized nitinol tubular structures will be designed through topology optimization [34,35]. In addition, to secure the contact between nitinol tube and sheath, it is recommended to weld the nitinol tube and sheath as an entire part, which will also further reduce the size of tool connection portion.…”

Section: Discussionmentioning

confidence: 99%

Distal End Force Sensing with Optical Fiber Bragg Gratings for Tendon-Sheath Mechanisms in Flexible Endoscopic Robots

Lai

Cao

et al. 2018

2018 IEEE International Conference on Robotics and Automation (ICRA)

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Accurate haptic feedback is a critical challenge for surgical robots, especially for flexible endoscopic surgical robots whose transmission systems are Tendon-Sheath Mechanisms (TSMs) with highly nonlinear friction profiles and force hysteresis. For distal end haptic sensing of TSMs, this paper, for the first time, proposes to measure the compression force on the sheath at the distal end so that the tension force on the tendon, which equals the compression force on the sheath, can be obtained. A new force sensor, i.e., a nitinol tube attached with an optical Fiber Bragg Grating (FBG) fiber, is proposed to measure the compression force on the sheath. This sensor, with similar diameter and configuration (hollow) as the sheath, can be compactly integrated with TSMs and surgical end-effectors. In this paper, mechanics analysis and verification tests are presented to reveal the relationship between the tension force on the tendon and the compression force on the sheath. The proposed force sensor was calibrated in tests with a sensitivity of 24.28 pm/N and integrated with a tendon-sheath driven grasper to demonstrate the effectiveness of the proposed approach and sensor. The proposed approach and sensor can also be applied for a variety of TSMs-driven systems, such as robotic fingers/hands, wearable devices, and rehabilitation devices.

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Section: Discussionmentioning

confidence: 99%

Distal End Force Sensing with Optical Fiber Bragg Gratings for Tendon-Sheath Mechanisms in Flexible Endoscopic Robots

Lai

Cao

et al. 2018

2018 IEEE International Conference on Robotics and Automation (ICRA)

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“…The so-called kinetostatic formulations, in one form or another, simultaneously aim to maximize the energy transmission between the input and output ports and mechanism's structural stiffness [21]. The mechanism performance is generally quantified using the concepts of mechanical advantage, geometric advantage, mechanical efficiency, flexibility-stiffness or mutual potential energy [24]. Although there is no single universally accepted formulation, it has been shown that these formulations produce almost similar topologies for the optimized compliant mechanisms [17], viz.…”

Section: Kinetostatic Formulationsmentioning

confidence: 99%

A simple and versatile topology optimization formulation for flexure synthesis

Koppen,

Langelaar,

van Keulen

2021

Preprint

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High-tech equipment critically relies on flexures for precise manipulation and measurement. Through elastic deformation, flexures offer extreme position repeatability within a limited range of motion in their degrees of freedom, while constraining motion in the degrees of constraint. Topology optimization proves a prospective tool for the design of short-stroke flexures, providing maximum design freedom and allowing for application-specific requirements. State-ofthe-art topology optimization formulations for flexure synthesis are subject to challenges like ease of use, versatility, implementation complexity, and computational cost, leaving a generally accepted formulation absent. This study proposes a novel topology optimization formulation for the synthesis of short-stroke flexures uniquely based on strain energy measures under prescribed displacement scenarios. The resulting self-adjoint optimization problem resembles great similarity to 'classic' compliance minimization and inherits similar implementation simplicity, computational efficiency, and convergence properties. Numerical examples demonstrate the versatility in flexure types and the extendability of additional design requirements. The provided source code encourages the formulation to be explored and applied in academia and industry.

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“…2 A flexure hinge can be customized to a specific motion; therefore, most of compliant mechanisms are flexure hinge based. 3 Compliant mechanisms with flexure hinges have been applied widely in precision positioning where small displacements are needed in a well-controlled environment. 4 For example, many types of compliant mechanisms have been developed for micro-component assembly in biotechnology.…”

Section: Introductionmentioning

confidence: 99%

Modelling and verification of fatigue damage for compliant mechanisms

Liu¹,

Ran³

et al. 2018

Robotica

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SUMMARYThis paper presents a model-based approach for the first time to identify the crack location for the hinge-based planar RRR compliant mechanism, a parallel micro-motion stage driven by piezoelectric (PZT) actuators. However, cracks more likely occur on a flexure hinge because it usually undergoes a periodic deformation in service, which eventually compromises mechanism's performance, positioning accuracy for instance. In this work, the pseudo-rigid-body method is used to develop kinematic and dynamic models of the RRR mechanism both in healthy and damaged conditions, where the crack is considered in terms of the rotational compliance of a flexible hinge. The crack location is determined by measuring PZT elongations, which represents the driving toque deviation because of the crack presence. Numerical simulation is conducted to verify the proposed approach, and the results show good match of the identified crack location with the assumed location. Finally, experiments on the RRR mechanism with a prefabricated crack is performed to further validate the proposed models; the experimental results yield a good consistence.

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On understanding of design problem formulation for compliant mechanisms through topology optimization

Cited by 24 publications

References 36 publications

Distal End Force Sensing with Optical Fiber Bragg Gratings for Tendon-Sheath Mechanisms in Flexible Endoscopic Robots

Distal End Force Sensing with Optical Fiber Bragg Gratings for Tendon-Sheath Mechanisms in Flexible Endoscopic Robots

A simple and versatile topology optimization formulation for flexure synthesis

Modelling and verification of fatigue damage for compliant mechanisms

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