Examine the Bending Stiffness of Generalized Kresling Modules for Robotic Manipulation

2020 ◽  
Author(s):  
Joshua Kaufmann ◽  
Suyi Li
Keyword(s):  
Analytical Modeling ◽  
Experimental Validation ◽  
Experimental Testing ◽  
Stable State ◽  
Building Blocks ◽  
Longitudinal Axis ◽  
Bending Stiffness ◽  
Robotic Manipulation ◽  
Stable States ◽  
Hinge Model

Abstract Via analytical modeling and experimental validation, this study examines the bending stiffness adaptation of bistable origami modules based on generalized Kresling pattern. These modules, which are the building blocks of an octopus-inspired robotic manipulator, can create a reconfigurable articulation via switching between their stable states. In this way, the manipulator can exhibit pseudo-linkage kinematics with lower control requirements and improved motion accuracy compared to completely soft manipulators. A key to achieving this reconfigurable articulation is that the underlying Kresling modules must show a sufficient difference in bending stiffness between their stable states. Therefore, this study aims to use both a nonlinear bar-hinge model and experimental testing to uncover the correlation between the module bending stiffness and the corresponding origami designs. The results show that the Kresling origami module can indeed exhibit a significant change in bending stiffness because of the reorientation of its triangular facets. That is, at one stable state, these facets align close to parallel to the longitudinal axis of the cylindrical-shaped module, so the module bending stiffness is relatively high and dominated by the facet stretching. However, at the other stable states, the triangular facets are orientated close to perpendicular to the longitudinal axis, so the bending stiffness is low and dominated by crease folding. The results of this study will provide the necessary design insights for constructing a fully functional manipulator with the desired articulation behavior.

scholarly journals Guided Formation of 3D Helical Mesostructures by Mechanical Buckling: Analytical Modeling and Experimental Validation

2016 ◽  
Vol 26 (17) ◽  
pp. 2909-2918 ◽  
Author(s):  
Yuan Liu ◽  
Zheng Yan ◽  
Qing Lin ◽  
Xuelin Guo ◽  
Mengdi Han ◽  
...  
Keyword(s):  
Analytical Modeling ◽  
Experimental Validation ◽  
Mechanical Buckling

scholarly journals Path-dependent institutions drive alternative stable states in conservation

2018 ◽  
Vol 116 (2) ◽  
pp. 689-694 ◽  
Author(s):  
Edward W. Tekwa ◽  
Eli P. Fenichel ◽  
Simon A. Levin ◽  
Malin L. Pinsky
Keyword(s):  
Renewable Resources ◽  
Path Dependence ◽  
Alternative Stable States ◽  
Stable State ◽  
Empirical Support ◽  
Stable States ◽  
Alternative Stable State ◽  
Important Challenge ◽  
Quantitative Analyses ◽  
Path Dependent

Understanding why some renewable resources are overharvested while others are conserved remains an important challenge. Most explanations focus on institutional or ecological differences among resources. Here, we provide theoretical and empirical evidence that conservation and overharvest can be alternative stable states within the same exclusive-resource management system because of path-dependent processes, including slow institutional adaptation. Surprisingly, this theory predicts that the alternative states of strong conservation or overharvest are most likely for resources that were previously thought to be easily conserved under optimal management or even open access. Quantitative analyses of harvest rates from 217 intensely managed fisheries supports the predictions. Fisheries’ harvest rates also showed transient dynamics characteristic of path dependence, as well as convergence to the alternative stable state after unexpected transitions. This statistical evidence for path dependence differs from previous empirical support that was based largely on case studies, experiments, and distributional analyses. Alternative stable states in conservation appear likely outcomes for many cooperatively managed renewable resources, which implies that achieving conservation outcomes hinges on harnessing existing policy tools to navigate transitions.

Examining the Coiling Motion of Soft Actuators Reinforced With Tilted Helix Fibers

2018 ◽  
Author(s):  
Ryan Geer ◽  
Suyi Li
Keyword(s):  
Longitudinal Axis ◽  
Robotic Manipulation ◽  
Proof Of Concept ◽  
Soft Actuator ◽  
Kevlar Fiber ◽  
New Family ◽  
End Caps ◽  
Soft Actuators ◽  
Unique Cell ◽  
Cell Wall Architecture

This study aims to examine the coiling and uncoiling motion of a soft pneumatic actuator reinforced with tilted helix fibers. Coiling motion can be quite useful for robotic manipulation and locomotion purposes. This research proposes and investigates a novel actuator that is inspired and derived from the unique cell wall architecture in the seed appendage of Stork’s Bill plant (Erodium Gruinum). These plant cells are reinforced by cellulose fibers distributed in a tilted helix pattern — helixes that are tilted at a certain angle with respect to the longitudinal axis of the cell. As a result, the seed appendage can coil and uncoil via a combination of twisting and bending. This paper discusses the design, fabrication, and testing of a soft actuator that can mimic this sophisticated motion. This actuator consists of Kevlar fiber thread wrapped around a silicon rubber body that has the shape of a tube. The tube will be capped at both ends so that it can be pressurized internally to induce motion. Once the design parameter has been chosen, the soft actuator are fabricated by 1) designing and 3D printing molds, 2) tube casting and fiber wrapping, and 3) creating the end caps for pressure sealing. Carefully executing these fabrication steps is essential because any errors could give undesired deformation. Several soft actuators prototypes are fabricated based on different design choices regarding the actuator radius, tube wall thickness, and the number of tilted helix fibers (aka. fiber coverage). Proof-of-concept tests show that these actuator prototypes can indeed exhibit a combined twisting and bending under internal pressurization: all are the necessary receipts to achieve the coiling and uncoiling motion. Result of this paper can pave the way for a new family of soft actuators capable of unprecedented and sophisticated actuation motions, which are particularly appealing for soft robot application.

Design and Characterization of Single Beam for Latching Electrothermal Microswitch

2012 ◽  
Vol 468-471 ◽  
pp. 286-289
Author(s):  
Ying Zhang ◽  
Hong Wang ◽  
Yan Wang ◽  
Sheng Ping Mao ◽  
Gui Fu Ding
Keyword(s):  
Mechanical Performance ◽  
Stable State ◽  
Cantilever Beams ◽  
Analysis Software ◽  
Stable States ◽  
Element Analysis ◽  
Single Beam ◽  
Fabrication And Characterization ◽  
Continuous Power

This paper presents the design, fabrication and characterization of single beam for latching electrothermal microswitch. This microswitch consists of two cantilever beams using bimorph electrothermal actuator with mechanical latching for performing low power bistable relay applications. A stable state can be acquired without continuous power which is only needed to switch between two stable states of the microactuator. The single beam is discussed mainly to judge the possibility of realizing the designed function. First, reasonable shape of the resistance is designed using finite element analysis software ANSYS. Then, mechanical performance was characterized by WYKO NT1100 optical profiling system, the tip deflection of single beam can meet the designed demand.

Bayesian Optimization of Equilibrium States in Elastomeric Beams

2021 ◽  
pp. 1-36
Author(s):  
David Yoo ◽  
Nathan Hertlein ◽  
Vincent Chen ◽  
Carson Willey ◽  
Andrew Gillman ◽  
...  
Keyword(s):  
Penalty Method ◽  
Vibration Isolation ◽  
Design Space ◽  
Strong Dependence ◽  
Series Representation ◽  
Building Blocks ◽  
Equilibrium States ◽  
Bayesian Optimization ◽  
Stable States ◽  
Beam Shape

Abstract Architected elastomeric beam networks have great potential for energy absorption, multi-resonant vibration isolation, and multi-bandgap elastic wave control, due to the reconfigurability and programmability of their mechanical buckling instabilities. However, navigating this design space is challenging due to bifurcations between mono- and bistable beam designs, inherent geometric nonlinearities, and the strong dependence of buckling properties on beam geometry. To investigate these challenges, we developed a Bayesian optimization framework to control the equilibrium states of an inclined elastomeric beam, while also tuning the energy to transition between these configurations. Leveraging symmetry to reduce the design space, the beam shape is parameterized using a Fourier series representation. A penalty method is developed to include monostable designs in objective functions with dependencies on bistable features, enabling monostable results to still be incorporated in the Gaussian Process surrogate and contribute to the optimization process. Two objectives are optimized in this study, including the position of the second stable equilibrium configuration and the ratio of output to input energy between the two stable states. A scalarized multi-objective optimization is also carried out to study the trade-off between equilibrium position and the energetics of transition between the stable states. The predicted designs are qualitatively verified through experimental testing. Collectively, the study explores a new parameter space for beam buckling, introduces a penalty method to regularize between mono- and bistable domains and provides a library of beams as building blocks to assemble and analyze in future studies.

Automated modal parameters identification of bistable composite plate using two-stage clustering of operational modal testing

2020 ◽  
pp. 002199832090308
Author(s):  
Mahdi Ghamami ◽  
Hassan Nahvi ◽  
Vahid Yaghoubi
Keyword(s):  
Analytical Method ◽  
Composite Plate ◽  
Ritz Method ◽  
Stable State ◽  
User Interaction ◽  
Modal Testing ◽  
Modal Parameters ◽  
Identification Algorithm ◽  
Stable States ◽  
Modal Parameters Identification

In recent years, smart structures have attracted much interest as morphing structures. One of the simplest types of these structures is bistable composite plate, which has many applications in aerospace, structures, actuators, etc. On the other hand, inverse problem theory provides conceptual ideas and methods for the practical solution of applied problems. These methods are opposite of the forward problem and define a model of the system based on output or observations. In this paper, a modified identification algorithm is used to determine the modal parameters of a bistable composite plate based on vibrational signals. Both analytical and experimental approaches have been considered and analytical method has been used to investigate the accuracy of identification algorithm, which has been performed based on experimental measurement. In the analytical method, static and free vibration behaviors of a cross-ply bistable composite plate are studied by the Hamilton's principle and the Rayleigh–Ritz method. The experimental approach is performed by an operational modal testing, which is a nondestructive test. The identification process does not require user interaction and the process uses only a single dataset and there is no need to repeat the test or data collection. The advantages of the proposed algorithm is the ability to determine the modal parameters of each stable state with high accuracy and robustness. A comparison of the natural frequencies shows that the identification of both stable states has been successful and the estimated modal parameters are in good agreement with the analytical and experimental results.

BLEMAT: Data Analytics and Machine Learning for Smart Building Occupancy Detection and Prediction

2019 ◽  
Vol 28 (06) ◽  
pp. 1960005 ◽  
Author(s):  
Saša Pešić ◽  
Milenko Tošić ◽  
Ognjen Iković ◽  
Miloš Radovanović ◽  
Mirjana Ivanović ◽  
...  
Keyword(s):  
Data Analysis ◽  
Experimental Validation ◽  
Building Blocks ◽  
Management Systems ◽  
Smart Building ◽  
Occupancy Detection ◽  
Occupancy Patterns ◽  
Building Management ◽  
Building Occupancy ◽  
Building Management Systems

Running costs of buildings represent a significant outlay for all businesses, thus finding a way to run facilities as efficiently as possible is vital. IoT-enabled Building Management Systems provide means for process and resource usage automation leading to overall efficiency improvements. Inferring spatial and temporal occupancy in all its forms (binary, numerical or continuous) is one of the key contextual inputs required for smart building management systems. In this work, we showcase design, implementation and experimental validation of a smart building occupancy detection and forecasting solution. The presented solution comprises three main building blocks: (1) A fog computing indoor positioning system (BLEMAT — Bluetooth Low Energy Microlocation Asset Tracking) which, combined with wireless access network monitoring processes, produces indoor location information in a semi-unsupervised manner; (2) Data analysis and pattern searching pipelines responsible for fusing data coming from different smart building and networking systems and deriving information on temporal and spatial occupancy patterns; (3) Long short-term memory (LSTM) neural networks trained to predict occupancy patterns in different areas of a smart building. Data analysis and neural network training are conducted on real-world smart building dataset which authors provide in public online repository. Experimental validation confirms that the proposed solution can provide actionable occupancy detection and prediction information, required by smart building management systems.

scholarly journals A Nonvolatile Fractional Order Memristor Model and its Complex Dynamics

Entropy ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 955 ◽  
Author(s):  
Wu ◽  
Wang ◽  
Iu ◽  
Shen ◽  
Zhou
Keyword(s):  
Fractional Order ◽  
Complex Dynamics ◽  
Equilibrium Points ◽  
Stable State ◽  
Electrical Characteristics ◽  
Chaotic Circuit ◽  
Stable States ◽  
Road Map ◽  
Chaotic Circuits ◽  
Integral Order

It is found that the fractional order memristor model can better simulate the characteristics of memristors and that chaotic circuits based on fractional order memristors also exhibit abundant dynamic behavior. This paper proposes an active fractional order memristor model and analyzes the electrical characteristics of the memristor via Power-Off Plot and Dynamic Road Map. We find that the fractional order memristor has continually stable states and is therefore nonvolatile. We also show that the memristor can be switched from one stable state to another under the excitation of appropriate voltage pulse. The volt–ampere hysteretic curves, frequency characteristics, and active characteristics of integral order and fractional order memristors are compared and analyzed. Based on the fractional order memristor and fractional order capacitor and inductor, we construct a chaotic circuit, of which the dynamic characteristics with respect to memristor’s parameters, fractional order α, and initial values are analyzed. The chaotic circuit has an infinite number of equilibrium points with multi-stability and exhibits coexisting bifurcations and coexisting attractors. Finally, the fractional order memristor-based chaotic circuit is verified by circuit simulations and DSP experiments.

scholarly journals An analytical modeling with experimental validation of bone temperature rise in drilling process

2020 ◽  
Vol 84 ◽  
pp. 151-160
Author(s):  
Foli Amewoui ◽  
Gaël Le Coz ◽  
Anne-Sophie Bonnet ◽  
Abdelhadi Moufki
Keyword(s):  
Temperature Rise ◽  
Analytical Modeling ◽  
Experimental Validation ◽  
Drilling Process
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