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Landolf Rhode-barbarigos - One of the best experts on this subject based on the ideXlab platform.
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Mechanism creation in Tensegrity structures by cellular morphogenesis
Acta Mechanica, 2020Co-Authors: Omar Aloui, Landolf Rhode-barbarigosAbstract:Tensegrity structures are self-equilibrated statically and kinematically indeterminate structures. Cellular morphogenesis represents a generative process for the composition of complex Tensegrity structures based on elementary cells. This article discusses the mechanism creation by the integration of mobility conditions in the generation of Tensegrity structures using cellular morphogenesis. The creation of finite and infinitesimal mechanisms in Tensegrity structures is described by the adhesion of cells sharing less than d nodes ( d being the dimension of the workspace) and by the fusion of cells with the removal of two edges. Parametric descriptions of the infinitesimal displacements in the case of trivial and finite mechanisms are derived by the analysis of rigid assemblies corresponding to the rigid parts of the structure. In addition, an interpretation of the degeneracy of Tensegrity structures in the case of self-stressable mechanisms is also presented. Analytical solutions of the degeneracy space for configurations resulting from adhesion and the fusion of two cells with the removal of two edges are described using symbolic calculations on the rigidity matrices of Tensegrity structures. Although the study focuses on selected configurations and arrangements, the generalization of the ideas and findings included in this paper can lead to the generation of Tensegrity structures with predefined static as well as kinematic properties, thus further enabling the application of Tensegrity systems in science and engineering.
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Cellular morphogenesis of three-dimensional Tensegrity structures
Computer Methods in Applied Mechanics and Engineering, 2019Co-Authors: Omar Aloui, David Orden, Jessica Flores, Landolf Rhode-barbarigosAbstract:Abstract The topology and form finding of Tensegrity structures have been studied extensively since the introduction of the Tensegrity concept. However, most of these studies address topology and form separately, where the former represented a research focus of rigidity theory and graph theory, while the latter attracted the attention of structural engineers. In this paper, a biomimetic approach for the combined topology and form finding of spatial Tensegrity systems is introduced. Tensegrity cells, elementary infinitesimally rigid self-stressed structures that have been proven to compose any Tensegrity, are used to generate more complex Tensegrity structures through the morphogenesis mechanisms of adhesion and fusion. A methodology for constructing a basis to describe the self-stress space is also provided. Through the definition of self-stress, the cellular morphogenesis method can integrate design considerations, such as a desired shape or number of nodes and members, providing great flexibility and control over the Tensegrity structure generated.
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Generation of planar Tensegrity structures through cellular multiplication
Applied Mathematical Modelling, 2018Co-Authors: Omar Aloui, David Orden, Landolf Rhode-barbarigosAbstract:Abstract Tensegrity structures are frameworks in a stable self-equilibrated prestress state that have been applied in various fields in science and engineering. Research into Tensegrity structures has resulted in reliable techniques for their form finding and analysis. However, most techniques address topology and form separately. This paper presents a bio-inspired approach for the combined topology identification and form finding of planar Tensegrity structures. Tensegrity structures are generated using Tensegrity cells (elementary stable self-stressed units that have been proven to compose any Tensegrity structure) according to two multiplication mechanisms: cellular adhesion and fusion. Changes in the dimension of the self-stress space of the structure are found to depend on the number of adhesion and fusion steps conducted as well as on the interaction among the cells composing the system. A methodology for defining a basis of the self-stress space is also provided. Through the definition of the equilibrium shape, the number of nodes and members as well as the number of self-stress states, the cellular multiplication method can integrate design considerations, providing great flexibility and control over the Tensegrity structure designed and opening the door to the development of a whole new realm of planar Tensegrity systems with controllable characteristics.
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A transformable Tensegrity-ring footbridge
2012Co-Authors: Landolf Rhode-barbarigos, René Motro, Ian F. C. SmithAbstract:Tensegrity structures are spatial reticulated structures composed of cables and struts. A tension-compression equilibrium leads to lightweight systems that change shape through length changes in their members. Active members thus control several degrees of freedom simultaneously. Tensegrity-ring modules are transformable circuit-pattern modules. The linear combination of Tensegrity rings has been shown to be viable for a footbridge application. Shape transformations of a ¼ scale four-ring-module Tensegrity-footbridge system are studied in this paper. Transformations are obtained employing active continuous cables and springs in the Tensegrity system to reduce the number of active elements. Obtaining a desired shape may involve independent actuation in several active elements. Independent actuation steps are found with the combination of a dynamic relaxation algorithm and a stochastic search algorithm.
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Designing Tensegrity modules for pedestrian bridges
Engineering Structures, 2010Co-Authors: Landolf Rhode-barbarigos, Nizar Bel Hadj Ali, René Motro, Ian F. C. SmithAbstract:Tensegrity systems are spatial structures composed of tensile and compression components in a self-equilibrated state of prestress. The Tensegrity concept has already been studied by researchers in various fields over the past decades. A family of Tensegrity modules that can offer promising solutions for civil engineering applications such as Tensegrity domes, towers and bridges is analyzed. Research into Tensegrity systems has resulted in reliable techniques for form finding and structural analysis. However, the Tensegrity concept is not yet part of mainstream structural design. This paper presents a design study of a Tensegrity-based pedestrian bridge. The structural performance of the bridge using three Tensegrity modules is evaluated through parametric studies. Design requirements for pedestrian bridges and results of parametric studies are used to define a design procedure that optimizes section sizes for this type of structure. A structural efficiency indicator is proposed and used to compare proposals for feasible bridge configurations. Design results illustrate that the hollow-rope Tensegrity bridge can efficiently meet typical design criteria.
Robert E. Skelton - One of the best experts on this subject based on the ideXlab platform.
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Design and control of Tensegrity morphing airfoils
Mechanics Research Communications, 2020Co-Authors: Muhao Chen, Jiacheng Liu, Robert E. SkeltonAbstract:Abstract We present a general approach of design, dynamics, and control for Tensegrity morphing airfoils. Firstly, based on reduced order Class-k Tensegrity dynamics, a shape control law for Tensegrity systems is derived. Then, we develop a method for discretizing continuous airfoil curves based on shape accuracy. This method is compared with conventional methods (i.e. evenly spacing and cosine spacing methods). A Tensegrity topology for shape controllable airfoil is proposed. A morphing Tensegrity airfoil example is given to demonstrate successful shape control. This work paves a road towards integrating structure and control design, the principles developed here can also be used for 3D morphing airfoil design and control of various kinds of Tensegrity structures.
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Meta-Tensegrity: Design of a Tensegrity prism with metal rubber
Composite Structures, 2018Co-Authors: Qicheng Zhang, Robert E. Skelton, Yousef Dobah, Fabrizio Scarpa, Fernando Fraternali, Dayi Zhang, Jie HongAbstract:Abstract A Tensegrity structure involves the presence of elements withstanding pure compression, and others under pure tension only. Metal rubber is introduced into a Tensegrity prism strut to create a mechanical metamaterial with energy absorption and tuneable dynamic properties. In this work we describe the design and development of the meta-Tensegrity structure with particular emphasis on the evaluation of parameters such as the structural size, the metal rubber stiffness, the initial internal force and the external compression load. Prototypes of Tensegrity prisms with and without metal rubber inserts have been assembled and subjected to quasi-static loading. The model used to design the meta Tensegrity prism has been then modified to take into account specific manufacturing and internal dissipation mechanisms typical of this configuration. The updated model provides a better comparison with the experimental results. Both the theoretical and experimental data show that the introduction of the metal rubber within the Tensegrity configuration contributes to improve significantly the energy absorption, and to reduce the stiffness of the whole Tensegrity structure.
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Shape Control of Tensegrity Airfoils
AIAA Guidance Navigation and Control Conference, 2016Co-Authors: James V. Henrickson, Robert E. Skelton, John ValasekAbstract:This paper develops and applies Tensegrity concepts to the design of shape-controllable 2D airfoils. After introducing Tensegrity systems and dynamics, a tension-driven shape control strategy is outlined, and a method of generating variable complexity Tensegrity airfoils is developed. The described shape control strategy is then applied to the task of transforming a given Tensegrity airfoil from some initial shape to a desired final shape. Results show the generation of Tensegrity systems that approximate various NACA 4series airfoil profiles, and simulation results demonstrate successful shape control of both symmetric and asymmetric Tensegrity airfoils.
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Shape Control of Tensegrity Structures
AIAA SPACE 2015 Conference and Exposition, 2015Co-Authors: James V. Henrickson, John Valasek, Robert E. SkeltonAbstract:Tensegrity is a relatively new approach to structural design that has seen great advances in recent years. The unique properties of Tensegrity structures allow for the design of deployable and lightweight structures|a combination highly applicable in the context of space systems. This work focuses on a rigorous development of shape control for Tensegrity
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Double-Helix Tensegrity Structures
AIAA Journal, 2015Co-Authors: Kenji Nagase, Robert E. SkeltonAbstract:This paper describes a class of Tensegrity systems that are formed from a common type of connectivity, having a double-helix configuration. Structures made from such internal patterns will be called a double-helix Tensegrity. This paper derives the connectivity matrix for the double-helix Tensegrity class of structures. This generalized common mathematical formulation will allow efficient computations for a large class of Tensegrity systems, which can have many different configurations, albeit employing the same rules for connecting components. Special cases of these configurations include torus, cylinders, paraboloids, spheres, ellipsoids, and other configurations.
Jonathan Bruce - One of the best experts on this subject based on the ideXlab platform.
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design and control of compliant Tensegrity robots through simulation and hardware validation
Journal of the Royal Society Interface, 2014Co-Authors: Ken Caluwaerts, Jeremie Despraz, Atil Iscen, Andrew P Sabelhaus, Jonathan BruceAbstract:To better understand the role of Tensegrity structures in biological systems and their application to robotics, the Dynamic Tensegrity Robotics Lab at NASA Ames Research Center, Moffett Field, CA, USA, has developed and validated two software environments for the analysis, simulation and design of Tensegrity robots. These tools, along with new control methodologies and the modular hardware components developed to validate them, are presented as a system for the design of actuated Tensegrity structures. As evidenced from their appearance in many biological systems, Tensegrity (‘tensile–integrity’) structures have unique physical properties that make them ideal for interaction with uncertain environments. Yet, these characteristics make design and control of bioinspired Tensegrity robots extremely challenging. This work presents the progress our tools have made in tackling the design and control challenges of spherical Tensegrity structures. We focus on this shape since it lends itself to rolling locomotion. The results of our analyses include multiple novel control approaches for mobility and terrain interaction of spherical Tensegrity structures that have been tested in simulation. A hardware prototype of a spherical six-bar Tensegrity, the Reservoir Compliant Tensegrity Robot, is used to empirically validate the accuracy of simulation.
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design and evolution of a modular Tensegrity robot platform
International Conference on Robotics and Automation, 2014Co-Authors: Jonathan Bruce, Ken Caluwaerts, Atil Iscen, Andrew P Sabelhaus, Vytas SunspiralAbstract:NASA Ames Research Center is developing a compliant modular Tensegrity robotic platform for planetary exploration. In this paper we present the design and evolution of the platform’s main hardware component, an untethered, robust Tensegrity strut, with rich sensor feedback and cable actuation. Each strut is a complete robot, and multiple struts can be combined together to form a wide range of complex Tensegrity robots. Our current goal for the Tensegrity robotic platform is the development of SUPERball, a 6-strut icosahedron underactuated Tensegrity robot aimed at dynamic locomotion for planetary exploration rovers and landers, but the aim is for the modular strut to enable a wide range of Tensegrity morphologies. SUPERball is a second generation prototype, evolving from the Tensegrity robot ReCTeR, which is also a modular, lightweight, highly compliant 6-strut Tensegrity robot that was used to validate our physics based NASA Tensegrity Robot Toolkit (NTRT) simulator. Many hardware design parameters of the SUPERball were driven by locomotion results obtained in our validated simulator. These evolutionary explorations helped constrain motor torque and speed parameters, along with strut and string stress. As construction of the hardware has finalized, we have also used the same evolutionary framework to evolve controllers that respect the built hardware parameters.
Omar Aloui - One of the best experts on this subject based on the ideXlab platform.
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Mechanism creation in Tensegrity structures by cellular morphogenesis
Acta Mechanica, 2020Co-Authors: Omar Aloui, Landolf Rhode-barbarigosAbstract:Tensegrity structures are self-equilibrated statically and kinematically indeterminate structures. Cellular morphogenesis represents a generative process for the composition of complex Tensegrity structures based on elementary cells. This article discusses the mechanism creation by the integration of mobility conditions in the generation of Tensegrity structures using cellular morphogenesis. The creation of finite and infinitesimal mechanisms in Tensegrity structures is described by the adhesion of cells sharing less than d nodes ( d being the dimension of the workspace) and by the fusion of cells with the removal of two edges. Parametric descriptions of the infinitesimal displacements in the case of trivial and finite mechanisms are derived by the analysis of rigid assemblies corresponding to the rigid parts of the structure. In addition, an interpretation of the degeneracy of Tensegrity structures in the case of self-stressable mechanisms is also presented. Analytical solutions of the degeneracy space for configurations resulting from adhesion and the fusion of two cells with the removal of two edges are described using symbolic calculations on the rigidity matrices of Tensegrity structures. Although the study focuses on selected configurations and arrangements, the generalization of the ideas and findings included in this paper can lead to the generation of Tensegrity structures with predefined static as well as kinematic properties, thus further enabling the application of Tensegrity systems in science and engineering.
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Cellular morphogenesis of three-dimensional Tensegrity structures
Computer Methods in Applied Mechanics and Engineering, 2019Co-Authors: Omar Aloui, David Orden, Jessica Flores, Landolf Rhode-barbarigosAbstract:Abstract The topology and form finding of Tensegrity structures have been studied extensively since the introduction of the Tensegrity concept. However, most of these studies address topology and form separately, where the former represented a research focus of rigidity theory and graph theory, while the latter attracted the attention of structural engineers. In this paper, a biomimetic approach for the combined topology and form finding of spatial Tensegrity systems is introduced. Tensegrity cells, elementary infinitesimally rigid self-stressed structures that have been proven to compose any Tensegrity, are used to generate more complex Tensegrity structures through the morphogenesis mechanisms of adhesion and fusion. A methodology for constructing a basis to describe the self-stress space is also provided. Through the definition of self-stress, the cellular morphogenesis method can integrate design considerations, such as a desired shape or number of nodes and members, providing great flexibility and control over the Tensegrity structure generated.
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Generation of planar Tensegrity structures through cellular multiplication
Applied Mathematical Modelling, 2018Co-Authors: Omar Aloui, David Orden, Landolf Rhode-barbarigosAbstract:Abstract Tensegrity structures are frameworks in a stable self-equilibrated prestress state that have been applied in various fields in science and engineering. Research into Tensegrity structures has resulted in reliable techniques for their form finding and analysis. However, most techniques address topology and form separately. This paper presents a bio-inspired approach for the combined topology identification and form finding of planar Tensegrity structures. Tensegrity structures are generated using Tensegrity cells (elementary stable self-stressed units that have been proven to compose any Tensegrity structure) according to two multiplication mechanisms: cellular adhesion and fusion. Changes in the dimension of the self-stress space of the structure are found to depend on the number of adhesion and fusion steps conducted as well as on the interaction among the cells composing the system. A methodology for defining a basis of the self-stress space is also provided. Through the definition of the equilibrium shape, the number of nodes and members as well as the number of self-stress states, the cellular multiplication method can integrate design considerations, providing great flexibility and control over the Tensegrity structure designed and opening the door to the development of a whole new realm of planar Tensegrity systems with controllable characteristics.
Ken Caluwaerts - One of the best experts on this subject based on the ideXlab platform.
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design and control of compliant Tensegrity robots through simulation and hardware validation
Journal of the Royal Society Interface, 2014Co-Authors: Ken Caluwaerts, Jeremie Despraz, Atil Iscen, Andrew P Sabelhaus, Jonathan BruceAbstract:To better understand the role of Tensegrity structures in biological systems and their application to robotics, the Dynamic Tensegrity Robotics Lab at NASA Ames Research Center, Moffett Field, CA, USA, has developed and validated two software environments for the analysis, simulation and design of Tensegrity robots. These tools, along with new control methodologies and the modular hardware components developed to validate them, are presented as a system for the design of actuated Tensegrity structures. As evidenced from their appearance in many biological systems, Tensegrity (‘tensile–integrity’) structures have unique physical properties that make them ideal for interaction with uncertain environments. Yet, these characteristics make design and control of bioinspired Tensegrity robots extremely challenging. This work presents the progress our tools have made in tackling the design and control challenges of spherical Tensegrity structures. We focus on this shape since it lends itself to rolling locomotion. The results of our analyses include multiple novel control approaches for mobility and terrain interaction of spherical Tensegrity structures that have been tested in simulation. A hardware prototype of a spherical six-bar Tensegrity, the Reservoir Compliant Tensegrity Robot, is used to empirically validate the accuracy of simulation.
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design and evolution of a modular Tensegrity robot platform
International Conference on Robotics and Automation, 2014Co-Authors: Jonathan Bruce, Ken Caluwaerts, Atil Iscen, Andrew P Sabelhaus, Vytas SunspiralAbstract:NASA Ames Research Center is developing a compliant modular Tensegrity robotic platform for planetary exploration. In this paper we present the design and evolution of the platform’s main hardware component, an untethered, robust Tensegrity strut, with rich sensor feedback and cable actuation. Each strut is a complete robot, and multiple struts can be combined together to form a wide range of complex Tensegrity robots. Our current goal for the Tensegrity robotic platform is the development of SUPERball, a 6-strut icosahedron underactuated Tensegrity robot aimed at dynamic locomotion for planetary exploration rovers and landers, but the aim is for the modular strut to enable a wide range of Tensegrity morphologies. SUPERball is a second generation prototype, evolving from the Tensegrity robot ReCTeR, which is also a modular, lightweight, highly compliant 6-strut Tensegrity robot that was used to validate our physics based NASA Tensegrity Robot Toolkit (NTRT) simulator. Many hardware design parameters of the SUPERball were driven by locomotion results obtained in our validated simulator. These evolutionary explorations helped constrain motor torque and speed parameters, along with strut and string stress. As construction of the hardware has finalized, we have also used the same evolutionary framework to evolve controllers that respect the built hardware parameters.
