Phenomena of nonlinear oscillation and special resonance of a dielectric elastomer minimum energy structure rotary joint

2015 ◽  
Vol 106 (13) ◽  
pp. 133504 ◽  
Author(s):  
Jianwen Zhao ◽  
Junyang Niu ◽  
David McCoul ◽  
Zhi Ren ◽  
Qibing Pei
Keyword(s):  
Nonlinear Oscillation ◽  
Minimum Energy ◽  
Dielectric Elastomer ◽  
Energy Structure ◽  
Rotary Joint

New Resonance Mode of Dielectric Elastomer Minimum Energy Structure

2016 ◽  
Vol 97 ◽  
pp. 48-56
Author(s):  
Jian Wen Zhao ◽  
Yong Ge ◽  
Shu Wang ◽  
Bo Huang
Keyword(s):  
Minimum Energy ◽  
Bending Moment ◽  
Input Voltage ◽  
Dielectric Elastomer ◽  
Resonance Mode ◽  
Vibrational Amplitude ◽  
Energy Structure ◽  
Rotary Joint ◽  
Nature Frequency ◽  
Voltage Frequency

The dielectric elastomer minimum energy structure (DEMES) can realize large angular deformations by a small voltage-induced strain of the dielectric elastomer, so it is a suitable candidate to make a rotary joint for a soft robot. Driven with an alternating electric field, the joint deformation vibrational frequency follows the input voltage frequency. However, the authors find that if the rotational angel over a negative angle during dynamic response, the resonance mode will be different from the traditional, the vibration with the largest amplitude does not occur while the voltage frequency is equal to natural response frequency of the joint. Rather, the vibrational amplitude will be quite large over a range of other frequencies, at which the voltage frequency is greater than one time of the nature frequency and smaller than two times. This phenomenon was analyzed by relationship between the bending angle, applied voltage and bending moment of the film to the frame on a timeline. This new resonance mode can be applied to some biomimetic soft robots that consist of DEMES rotary joint.

A Compliant Translational Mechanism Based on Dielectric Elastomer Actuators

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Chuc Huu Nguyen ◽  
Gursel Alici ◽  
Rahim Mutlu
Keyword(s):  
Position Control ◽  
Translational Motion ◽  
Minimum Energy ◽  
Dielectric Elastomer ◽  
Energy Structure ◽  
Driving Voltage ◽  
Experimental Frequency ◽  
Dielectric Elastomer Actuators ◽  
Proposed Model ◽  
Crank Mechanism

This paper reports on a linear actuation mechanism in the form of a parallel-crank mechanism (i.e., double-crank mechanism) articulated with two dielectric elastomer actuators working in parallel that are fabricated as a minimum energy structure. This structure is established by stretching a dielectric elastomer (DE) film (VHB4910) over a polyethylene terephthalate (PET) frame so that the energy released from the stretched DE film is stored in the frame as bending energy. The mechanism can output a translational motion under a driving voltage applied between two electrodes of the DE film. We have proposed visco-elastic models for the DE film and the frame of the actuator so that the mechanical properties of the actuator can more accurately be incorporated into the mechanism model. The proposed model accurately predicts the experimental frequency response of the mechanism at different voltages. In addition, an inversion-based feedforward controller was successfully implemented in order to further validate the proposed model for sensorless position control of the actuators and the parallel-crank mechanism articulated with these actuators.

A method to increase the dynamic deformation of a dielectric elastomer minimum energy structures rotary joint without increase of the voltage amplitude

2019 ◽  
Vol 30 (14) ◽  
pp. 2091-2098
Author(s):  
Shu Wang ◽  
Bo Huang ◽  
David McCoul ◽  
Xinbo Wang ◽  
Jianwen Zhao
Keyword(s):  
Duty Cycle ◽  
Applied Voltage ◽  
Dynamic Deformation ◽  
Minimum Energy ◽  
Dielectric Elastomer ◽  
Voltage Amplitude ◽  
Rotary Joint ◽  
Optimization Principle ◽  
Key Factor ◽  
The Moment

The traditional method to increase the dynamic deformation of a dielectric elastomer actuator is to increase the voltage applied on the dielectric elastomer. Based on the characteristics of dielectric elastomer minimum energy structures, a method to increase the deformation is proposed, which does not increase the applied voltage amplitude. We found that the frequency and duty cycle of the applied voltage will influence the range of deformation strongly, and the moment the power is switched off, [Formula: see text] is a key factor to the deformation range; therefore, the frequency and duty cycle can be optimized to obtain the largest deformation range with an expected vibrational frequency. Two groups of experiments were compared to validate this optimization principle, and the range of deformation with optimized parameters was found to be 1.67 times larger on average than with normal parameters.

Asymmetry bistability for a coupled dielectric elastomer minimum energy structure

2016 ◽  
Vol 25 (11) ◽  
pp. 115023 ◽  
Author(s):  
Wen-Bo Li ◽  
Wen-Ming Zhang ◽  
Hong-Xiang Zou ◽  
Zhi-Ke Peng ◽  
Guang Meng
Keyword(s):  
Minimum Energy ◽  
Dielectric Elastomer ◽  
Energy Structure

scholarly journals RNA Secondary Structures with Limited Base Pair Span: Exact Backtracking and an Application

Genes ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 14
Author(s):  
Ronny Lorenz ◽  
Peter F. Stadler
Keyword(s):  
Base Pair ◽  
Structure Prediction ◽  
Secondary Structure Prediction ◽  
Minimum Energy ◽  
Optimal Structure ◽  
Energy Structure ◽  
C Elegans ◽  
Z Scores ◽  
Limited Base ◽  
Optimal Span

The accuracy of RNA secondary structure prediction decreases with the span of a base pair, i.e., the number of nucleotides that it encloses. The dynamic programming algorithms for RNA folding can be easily specialized in order to consider only base pairs with a limited span L, reducing the memory requirements to O(nL), and further to O(n) by interleaving backtracking. However, the latter is an approximation that precludes the retrieval of the globally optimal structure. So far, the ViennaRNA package therefore does not provide a tool for computing optimal, span-restricted minimum energy structure. Here, we report on an efficient backtracking algorithm that reconstructs the globally optimal structure from the locally optimal fragments that are produced by the interleaved backtracking implemented in RNALfold. An implementation is integrated into the ViennaRNA package. The forward and the backtracking recursions of RNALfold are both easily constrained to structural components with a sufficiently negative z-scores. This provides a convenient method in order to identify hyper-stable structural elements. A screen of the C. elegans genome shows that such features are more abundant in real genomic sequences when compared to a di-nucleotide shuffled background model.

Finite element modelling of dielectric elastomer minimum energy structures

2008 ◽  
Vol 94 (3) ◽  
pp. 507-514 ◽  
Author(s):  
Benjamin O’Brien ◽  
Thomas McKay ◽  
Emilio Calius ◽  
Shane Xie ◽  
Iain Anderson
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Minimum Energy ◽  
Dielectric Elastomer ◽  
Element Modelling
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