Dynamics
Read here about the study of motion and changes in motion in the context of tensegrity structures. Responsive architecture is also discussed here, as tensegrity technologies are often applied in this evolving practice.
Overview
Generally speaking, researchers involved in dynamics study how a physical system might develop or alter over time and study the causes of those changes. In the field of [[1]], the study of the causes of motion and changes in motion is dynamics. In other words the study of [[2]] and why objects are in [[3]]. //Dynamics// includes the study of the effect of torques on motion. These are in contrast to [[4]], the branch of [mechanics] that describes the motion of objects without consideration of the causes leading to the motion.
In tensegrity studies, there is a great deal of research into dynamic structures, being structures that can change their morphology, or shape, in response to control signals.
Responsive Architecture
Responsive architecture is an evolving field of architectural practice and research. Responsive architectures are those that measure actual environmental conditions (via sensors) to enable buildings to adapt their form, shape, color or character responsively (via actuators). Responsive architectures aim to refine and extend the discipline of architecture by improving the energy performance of buildings with responsive technologies while also producing buildings that reflect the technological and cultural conditions of our time.
Responsive architectures distinguish themselves from other forms of interactive design by incorporating intelligent and responsive technologies into the core elements of a building's fabric. For example: by incorporating responsive technologies into the structural systems of buildings architects have the ability to tie the shape of a building directly to its environment. This enables architects to reconsider the way they design and construct space while striving to advance the discipline rather than applying patchworks of intelligent technologies to an existing vision of "building".
Tensegrity is significant to the practice of responsive architecture because its strict division of tension and compression enables the deployment of efficient and innovative control systems, actuators, and shape-changing components. The goal is to limit and reduce the impact of buildings on natural environments.
Actuated Tensegrity
Actuated tensegrity is the term used by Tristan d'Estree Sterk and Robert Skelton in their development of dynamic tensegrity structures. Actuated tensegrities have pneumatically controlled rods and wires that change the shape of a tensegrity structure in response to sensors both outside and inside the structure.
Robotoics
Dynamic tensegrity structures are often implemented in robotics, see robotics.
Selected Readings in Tensegrity Dynamics
Some selected readings on the application of tensegrity structures and concepts to dynamic applications and theories.
Geometry of Dynamic Structure
Geometry of Dynamic Structure by Diehl Link: [[5]] Link, [[6]]
Biotensegrity is a central metaphor used by Faith Diehl in this powerpoint addressing human organizational structure and operations. Title, "The Geometry of Dynamic Structure, A Fundamental Pattern of Organizational Architecture for Adaptive Transformation and Success in a Changing World Faith Diehl Independent," PowerPoint 1999, Peer Presentation March 2006, PowerPoint plus introductory pages and references posted on SSRN July 2009. This is a static copy, the latest versions are hosted at [[7]].
Author's abstract: The world is changing rapidly, placing increasing pressure on organizational systems to develop structures, processes and cultures that facilitate ongoing transformation. For half a century, a growing understanding of adaptive mechanisms in biological systems has provided metaphors and conceptual possibilities for organizational process and culture that facilitate change. In this presentation, the structure of living dynamic systems is identified as a critical component of adaptive capacity. A fundamental geometry is introduced that is observed in highly evolved systems – from the micro level in biology to the macro level in societal level organization. It appears that the fundamental structural geometry of dynamic living systems is ubiquitous – applying to all levels. Based on this observation, the author proposes that science is more than a metaphor for social phenomenon, and that organizations are a higher level of biological complexity. This proposition goes beyond a conceptual framework. It provides access to the entire range of advances in the natural and health sciences as templates for understanding and for the development of concrete tools for observation, measurement, intervention and design of organizations. The mechanical properties of this living architecture allows for a high level of elasticity, rapid redistribution of pressure and tension, distribution of information, and harmonic potential – creating conditions for both wholeness and adaptive capacity. The components are distinct, occur in predictable proportion, and appear to emerge in a particular sequence. With these understandings and a growing understanding of how they manifest in organizations, it becomes possible to develop a science of transformation. This presentation is intended to create awareness of the geometry of dynamic structure – contributing to understanding and greater freedom to cooperate responsibly with emergent design as well as co-create design possibilities. Application of the fundamental geometric pattern to organizational structure is one of the most powerful responses to the pressures of a rapidly changing world. For more information on biotensegrity, see [[8]]
Synchronised Activation of Tensegrity Grids
Synchronised Activation of Single-Curved Tensegrity Grids for Responsive Architecture by Herder Link: [[9]]
Herder's Actuated tensegrity (2008) used computational design tools to develop a tensegrity based load bearing structure that is able to change shape. He used synchronized actuation in a regular tensegrity grid. See http://www.arnoudherder.nl/Projects/Tensegrity/Schakel1.html or his YouTube channel, http://www.youtube.com/user/arnoudherder
Stability Conjecture
Stability Conjecture in the Theory of Tensegrity Structures by Volokh. International Journal of Structural Stability and Dynamics Vol. 3, No. 1 (2003) 1–16 c World Scientific Publishing Company. Link: [[10]]
Morphing Skins on Aircraft
Morphing Skins on Aircraft for Shape Change and Area Increase by Thill, Etches, Bond Et Al Link: [[11]]
A review of morphing concepts, including dynamic tensegrity structures, with a strong focus on morphing skins. Morphing technology on aircraft has found increased interest over the last decade because it is likely to enhance performance and efficiency over a wider range of flight conditions. For example, morphing wing geometry in flight may improve overall flight performance. It is found that anisotropic and variable stiffness structures offer potential for shape change and small area increase on aircraft wings. Concepts herein focus on those structures where primary loads are transmitted in the spanwise direction and a morphing function is achieved via chordwise flexibility. To meet desirable shape changes, stiffnesses can either be tailored or actively controlled to guarantee flexibility in the chordwise (or spanwise) direction with tailored actuation forces. Hence, corrugated structures, segmented structures, reinforced elastomers or flexible matrix composite tubes embedded in a low modulus membrane are all possible structures for morphing skins. For large wing area changes a particularly attractive solution could adopt deployable structures as no internal stresses are generated when their surface area is increased. Tensegrity is discussed as a form of cellular truss (also called compliant structure, or variable geometry trusses) made from octahedral unit cells, by Ramrakhyani. In tensegrity tendons, possibly SMA wires, make it possible to change the shape of the unit cell by lengthening or shortening the cables. Results showed that a tendon actuated wing has a similar mass than a conventional wing for the same design requirements but allows larger deflections. Ramrakhyani et al state that aeroelastic effects might be possible to address with active controls. Four skin solutions were suggested which were described earlier: high strain-capable materials, folded inner skins, multilayered skins and segmented skins. Wiggins also looked at tensegrity structures that change their spanwise camber elliptically i.e. droop the wing tip.
Dynamic Behavior and Vibration Control
Dynamic Behavior and Vibration Control of a Tensegrity Structure by Ali, Smith Link: [[12]]
I. F. Smith reports on control of a tensegrity structure. The structure is based on a nucleated compressed module, like a children's "jack", being 6 struts emanating orthogonally from a central ball like the (0,0,0) nexus of a 3D Cartesian coordinate framework. Shaking this structure confirmed the obvious, that control of the self-stress influences the dynamic behavior. The authors then propose a vibration control strategy much like tuning a musical instrument, where based on small movements of active struts are enacted in order to shift the natural resonant frequencies away from excitation.
Cellular Cytoskeleton Dynamical Behavior
Cytoskeleton Dynamical Behavior Approached By A Granular Tensegrity Model by Jean-Louis Milan, Sylvie Wendling-Mansuy, Michel Jean and Patrick Chabrand, Laboratoire d'Aérodynamique et de Biomécanique du Mouvement, CNRS-USR2164 ²Laboratoire de Mécanique et d’Acoustique, CNRS-UPR 7051 Université de la Méditerranée, Marseille, France. email: milan@morille.univ-mrs.fr, ISB XXth Congress - ASB 29th Annual Meeting July 31 - August 5, Cleveland, Ohio
Course outline Including Dynamic Tensegrity
MT1 Short Course for ACC 2009 Link: http://www.scribd.com/doc/29350944/MT1-Short-Course-for-ACC-2009
Course outline. The purpose of this course is to provide some analytical machinery that can be useful to integrate structure and control design. A critical focus is to determine the optimal complexity of the minimal mass structure, and to show that the optimized structure usually has a finite complexity. The first challenge is to choose the right paradigm for structure design. A tensegrity paradigm for structures (an assembly of “sticks” and “strings”) will allow one to modify the equilibrium of the structure to achieve the new desired shape, so that power is not required to hold the new shape. Such cooperation between the static and dynamic properties of the structure and the control system can only be accomplished by a structure design paradigm that maintains an extremely high degree of “controllability” during all phases of the structure design. This requires new types of structures and the tensegrity structural paradigm is the only one the authors have found with these properties.
Links and References=
Wikipedia links on [Dynamics, [Architecture