Creating Rigid Foldability to Enable Mobility of Origami-Inspired Mechanisms

Alden Yellowhorse; Larry L. Howell

doi:10.1115/1.4029923

Creating Rigid Foldability to Enable Mobility of Origami-Inspired Mechanisms

Journal of Mechanisms and Robotics ◽

10.1115/1.4029923 ◽

2015 ◽

Vol 8 (1) ◽

Cited By ~ 7

Author(s):

Alden Yellowhorse ◽

Larry L. Howell

Keyword(s):

Design Guidelines ◽

Degree Of Freedom ◽

Engineering Applications

Rigidly foldable origami crease patterns can be translated into corresponding rigid mechanisms with at least one degree of freedom. However, origami crease patterns of interest for engineering applications are not always rigidly foldable, and designers trying to adapt a crease pattern may be confronted with the need to add more mobility to their design. This paper presents design guidelines for making alterations to a crease pattern to make it rigidly foldable. Adding creases, removing panels, and splitting creases are presented as potential alterations for increasing mobility, and approaches for determining the position and number of alterations are discussed. This paper also investigates means for reducing the number of changes necessary to achieve this condition. The approach is developed in general and illustrated through a demonstrative example.

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Effects of human-induced load models on tuned mass damper in reducing floor vibration

Advances in Structural Engineering ◽

10.1177/1369433219843709 ◽

2019 ◽

Vol 22 (11) ◽

pp. 2449-2463

Author(s):

Jun Chen ◽

Ziping Han ◽

Ruotian Xu

Keyword(s):

Response Spectra ◽

Tuned Mass Damper ◽

Design Guidelines ◽

Degree Of Freedom ◽

Dynamic Responses ◽

Single Degree Of Freedom ◽

Load Model ◽

Load Models ◽

Single Degree ◽

Mass Damper

Dozens of human-induced load models for individual walking and jumping have been proposed in the past decades by researchers and are recommended in various design guidelines. These models differ from each other in terms of function orders, coefficients, and phase angles. When designing structures subjected to human-induced loads, in many cases, a load model is subjectively selected by the design engineer. The effects of different models on prediction of structural responses and efficiency of vibration control devices such as a tuned mass damper, however, are not clear. This article investigates the influence of human-induced load models on performance of tuned mass damper in reducing floor vibrations. Extensive numerical simulations were conducted on a single-degree-of-freedom system with one tuned mass damper, whose dynamic responses to six walking and four jumping load models were calculated and compared. The results show a maximum three times difference in the acceleration responses among all load models. Acceleration response spectra of the single-degree-of-freedom system with and without a tuned mass damper were also computed and the response reduction coefficients were determined accordingly. Comparison shows that the reduction coefficient curves have nearly the same tendency for different load models and a tuned mass damper with 5% mass ratio is able to achieve 50%–75% response reduction when the structure’s natural frequency is in multiples of the walking or jumping frequency. All the results indicate that a proper load model is crucial for structural response calculation and consequently the design of tuned mass damper device.

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Rigid Foldability of Triangle-Twist Origami Pattern and its Derived 6R Linkage

Volume 5B: 41st Mechanisms and Robotics Conference ◽

10.1115/detc2017-68063 ◽

2017 ◽

Author(s):

Rui Peng ◽

Jiayao Ma ◽

Yan Chen

Keyword(s):

Theoretical Method ◽

Geometric Parameters ◽

Degree Of Freedom ◽

Space Structures ◽

Engineering Applications ◽

Systematic Method ◽

Mountain Valley ◽

Folding Pattern ◽

Spatial Linkages ◽

Spherical Linkages

Rigid origami is an important subset of origami with broad engineering applications from space structures to metamaterials. The rigid foldability of an origami pattern is determined by both the geometric parameters and the mountain-valley crease assignment. In this paper, by using the equivalent relationships between origami vertices and spherical linkages, a systematic method was proposed to analyze the motion of the triangle-twist pattern with varying distribution of mountain and valley creases, and its rigid folding types were identified. Moreover, kirigami technology was applied to the rigid folding pattern without changing its degree of freedom, from which a new kind of overconstrained 6R linkage was developed. The theoretical method proposed in this paper can be readily extended to study other types of origami patterns, which will in turn help to design structures with large deployable ratio as well as some new spatial linkages.

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Simulation and Design of Two-Degree-of-Freedom Underactuated Mechanical Fingers

Volume 2A: 24th Biennial Mechanisms Conference ◽

10.1115/96-detc/mech-1562 ◽

1996 ◽

Author(s):

Thierry Laliberté ◽

Clément M. Gosselin

Keyword(s):

Design Guidelines ◽

Degree Of Freedom ◽

Simulation Tool ◽

Mechanical Hand ◽

Shape Adaptation ◽

Reduced Complexity ◽

Simulation Results ◽

Two Degree Of Freedom ◽

Underactuated Finger ◽

Promising Avenue

Abstract The design of underactuated mechanical fingers is addressed in this article. The objective of the research is to design a robust mechanical hand capable of performing industrial tasks involving the grasping of a wide variety of objects with large forces. To this end, the taxonomy of the grasps is first reviewed. Then, the principle of underactuation — which leads to shape adaptation of the hands — is introduced and a review of the existing underactuated mechanical hands is provided. Architectures of two-degree-of-freedom underactuated fingers are then proposed and a simulation tool is designed to analyze their behavior. It is shown that underactuation is a very promising avenue when only grasping is required (no manipulation). Simulation results are given and discussed in order to illustrate the usefulness of the simulator and general design guidelines are proposed. Finally, a design of an underactuated finger is presented as an example. The design presented here demonstrates that the use of underactuation can lead to versatile grasping capabilities with reduced complexity.

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Harmonic Analysis of Dynamic Systems With Nonsymmetric Nonlinearities

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.3426393 ◽

1979 ◽

Vol 101 (1) ◽

pp. 31-36 ◽

Cited By ~ 14

Author(s):

P-T. D. Spanos ◽

W. D. Iwan

Keyword(s):

Steady State ◽

Harmonic Analysis ◽

Linear Systems ◽

Dynamic Systems ◽

Approximate Solutions ◽

Steady State Solution ◽

Degree Of Freedom ◽

Equivalent Linearization ◽

Engineering Applications ◽

Vehicle System

The generalized method of equivalent linearization is modified to be applicable for multi-degree-of-freedom dynamic systems with nonsymmetric nonlinearities subjected to harmonic monofrequency excitation. Readily applicable formulas are given for the construction of the equivalent linear systems related to a class of systems commonly encountered in engineering applications. As an example of its application, the proposed method is used to generate an approximate steady-state solution for a simple vehicle system. The accuracy of the approximate solutions is determined.

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Rigid Foldability of Generalized Triangle Twist Origami Pattern and Its Derived 6R Linkages

Journal of Mechanisms and Robotics ◽

10.1115/1.4040439 ◽

2018 ◽

Vol 10 (5) ◽

Cited By ~ 9

Author(s):

Huijuan Feng ◽

Rui Peng ◽

Jiayao Ma ◽

Yan Chen

Keyword(s):

Degree Of Freedom ◽

Geometrical Parameters ◽

Engineering Applications ◽

Systematic Method ◽

Mountain Valley ◽

Foldable Structures ◽

New Type ◽

Spherical Linkages ◽

Kinematic Equivalence ◽

Overconstrained Linkages

Rigid origami is a restrictive form of origami that permits continuous motion between folded and unfolded states along the predetermined creases without stretching or bending of the facets. It has great potential in engineering applications, such as foldable structures that consist of rigid materials. The rigid foldability is an important characteristic of an origami pattern, which is determined by both the geometrical parameters and the mountain-valley crease (M-V) assignments. In this paper, we present a systematic method to analyze the rigid foldability and motion of the generalized triangle twist origami pattern using the kinematic equivalence between the rigid origami and the spherical linkages. All schemes of M-V assignment are derived based on the flat-foldable conditions among which rigidly foldable ones are identified. Moreover, a new type of overconstrained 6R linkage and a variation of doubly collapsible octahedral Bricard are developed by applying kirigami technique to the rigidly foldable pattern without changing its degree-of-freedom. The proposed method opens up a new way to generate spatial overconstrained linkages from the network of spherical linkages. It can be readily extended to other types of origami patterns.

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Inelastic displacement spectra for Chinese highway bridges characterized by single-degree-of-freedom bilinear systems

Advances in Structural Engineering ◽

10.1177/1369433219857845 ◽

2019 ◽

Vol 22 (14) ◽

pp. 3066-3085

Author(s):

Yi-feng Wu ◽

Ai-qun Li ◽

Hao Wang

Keyword(s):

Highway Bridges ◽

Design Guidelines ◽

Degree Of Freedom ◽

Single Degree Of Freedom ◽

Inelastic Displacement ◽

Single Degree ◽

Displacement Spectra ◽

Displacement Ratio ◽

Displacement Demand ◽

Inelastic Displacement Ratio

As for the inelastic displacement demand of a single-degree-of-freedom system, previous studies usually focus on the strength reduction factor, R, or the inelastic displacement ratio, C. Only a little literature reports the direct statistical results of the mean inelastic displacement spectra, Sd. Based on 308 earthquake records selected from three types of site soil, differences between the direct mean Sd and the indirect ones that respectively derived from mean R and mean Cμ are investigated, in which Cμ refers to the constant ductility inelastic displacement ratio. It is found the indirect Sd will introduce errors for using mean R and mean Cμ, while the dispersion of the direct spectra need to be reduced before putting into practice. Two methods, the period normalized method and the spectra-matching method, are employed to address the dispersion problem, and the latter one that modified a record to make its acceleration response spectra compatible with the specified standard, Chinese highway bridge seismic design guidelines in this study, works with more acceptable performance. Finally, a comprehensive equation is proposed to characterize the spectra-matching mean Sd, the practicality and efficiency of the identified parameters in the equation are verified. It is advisable to use the proposed equation to assess the inelastic displacement demand of Chinese highway bridges characterized by single-degree-of-freedom bilinear system, and the procedures to obtain the displacement spectra can also be utilized for other corresponding researches.

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Polyhedral Single Degree-of-freedom Expanding Structures: Design and Prototypes

Journal of Mechanical Design ◽

10.1115/1.1480413 ◽

2002 ◽

Vol 124 (3) ◽

pp. 473-478 ◽

Cited By ~ 36

Author(s):

Sunil K. Agrawal ◽

Saravana Kumar ◽

Mark Yim

Keyword(s):

Optimal Control ◽

Daily Life ◽

Degree Of Freedom ◽

Engineering Applications ◽

Single Degree Of Freedom ◽

Single Degree ◽

Entire Structure

Some engineering applications require structures to expand and contract in size, while retaining their exterior shape. The applications range from mundane daily life objects to more fancy art structures. In contrast to a multi degree-of-freedom structure, a single degree-of-freedom structure can be driven by a single actuator, reducing cost and simplifying the control. In this paper, we study single degree-of-freedom structures that can be formed by a lattice of single degree-of-freedom polyhedral expanding units. Due to built-in symmetries, the entire structure can expand and contract as one of the units in the structure is actuated. The paper describes the design of polyhedral single degree-of-freedom systems, the structures of their dynamics/optimal control, and results from construction prototypes.

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