Evolution selects for structural adaptations which are maximally efficient – tensegrity structures, which combine flexibility, resilience, strength, with minimal energy and material requirements, are optimum solutions to these demands. These models are, in a sense, attempts to reverse engineer evolution. The method was to build from geometry (nature of structure) towards gross vertebrate anatomy (structure of nature). Through many attempts, a complex tensegrity skeleton has been designed which intriguingly reproduce the movements and functions of human anatomy. The following models highlight sections of that tensegrity skeleton.
I have been researching and helping to develop the concepts that underlie the theory of biotensegrity for over 30 years. And for the past 20 years I’ve focused on designing and building models that illustrate this principle operating at the level of structural anatomy in vertebrates. I’ve been contacted by hundreds of people over this period, and have had many fruitful and interesting conversations about tensegrity and biology. The tensegrity models below illustrate aspects of structural anatomy. They are not depicting actual structures so much as kinematics of the body and the force vectors acting upon it.
Unfortunately, at this time these models are not for sale. Some simple tensegrity models including my Single Tensioned Pelvis model can be found at www.anatomytrains.com
Single Tensioned Pelvis
This model illustrate the complex motion generated by the pelvic ring while walking and/or twisting the torso. Tension components can be altered (shortened and lengthened) to demonstrate distortions and dysfunctions in posture and mobility. A change in one tension element affects the balance and symmetry in all three dimensions.
8″(H) X 8″(W) X 4″(D)
45cm(L) X 10cm(W) X 40cm(D)
quick reference sheet (pdf 2.3Mb)
Double Tensioned Pelvis
This model adds a second tension net; a deep layer and a more superficial layer. The deeper tension net is under a higher level of tension than the surface net on the assumption that the deeper layers of ligaments and muscles are ‘holding’ a greater tensile load that the superficial muscles. Curiously, when a distortion is introduced to the deep layer (increased tension or shortening of one component) the superficial layer immediately above responds by loosening while on the opposite side the reverse is the case and the tension increases. (diagram 6) This suggests that when a distortion occurs the superficial layer takes up a portion of the work the deeper layer was doing, perhaps to it’s detriment. Overall a kind of balance or net resultant of forces is maintained even if the figure is obviously distorted. (see the explanation and photos that accompanies the schematic torso)
10″(L) X 4″(W) X 8″(D)
45cm(L) X 10cm(W) X 40cm(D)
quick reference sheet (pdf 1.4Mb)
The representation of the leg and foot combines several different tensegrity elements. The pelvic connection is indicated by an expanded octahedral structure. The knee joint is suggested by a modified octahedral tensegrity structure that transfers weight from the femur and torso above through a connecting joint that allows limited flexibility in one axis. An attempt has been made to model the forces transferred from the tibia to the talus and the calcaneus using a four strut rotational tensegrity (this model can demonstrate pronation to some extent). Additional struts are then added to suggest the tarsals and metatarsals. The photos illustrate the essential stability of the structure combined with flexion joints, and medial and lateral arches. The resulting form is stable and self-supporting yet none of the compression elements are in direct weight bearing contact.
24″ (H) X 8″(D)
60cm(H) X 20cm(D)
quick reference sheet (pdf 1.6Mb)
Tetrahedral Vertebral Mast
Each vertebral body in a spine bears a formal resemblance to a stellated tetrahedron. It is possible to arrange a series of these stellated tetrahedrons as a tensegrity mast, such that the equivalent properties of load bearing combined with flexibility in rotation and bending is demonstrated.
14″ (H) X 4″(W) X 4″(D)
36cm (H) x 10cm (W) X 10cm (D)
quick reference sheet (pdf 3.2Mb)
Spiral Vertebral Mast
This mast is composed of seven compression spirals and seven tension spirals. Half spiral clockwise the other half counter clockwise. It suggests the agility of a snake and the strength and flexibility of a giraffe’s neck.
18″ (H) X 4″ (D)
45 cm (H) X 10 cm (D)
quick reference sheet (pdf 3.2Mb)
Animated Spiral Tensegrity Mast
A three-fold tensegrity spiral mast composed of wooden struts and an elastic tension net is actuated by using three vertical control lines.(six control lines give a greater degree of control however). Given the proper ratio of elastic tension to non-elastic control lines, such a mast demonstrates multiple degrees of freedom and a wide range of motion. Applications include robotic appendages that work like the Canada Arm on the International Space Station, prosthetic devices and exoskeletal support systems. Additionally such a mast illustrates the force vectors active in living forms such as an octopus, an elephant trunk, or a cat’s tail for example. Such a mast also schematizes how fascial support in the spine can assist in lateral and rotational movement but also provides stability by stiffening the mast when required by tightening the control lines.
20″ (H) X 4″ (D)
50cm (H) X 10cm (D)
The Tensegrity Icosahedron is a balanced tensegrity with three fold symmetry . Shortening one tension member will unbalance the figure in all three dimensions. This model can show how local injury affects the entire body.
Tensegrity Schematic Torso
A simplified schematic model of the torso made in wood. A useful diagnostic tool that allows simple distortions in symmetry to represent fundamental dysfunctions in human anatomy and suggest possible therapeutic interventions.
12″ (H) X 8″ (W) X 5″(D)
30cm(H) X 20cm(W) X 13cm(D)
quick reference sheet (pdf 2.9Mb)
Torso with Pelvis and Femurs
This model puts together the torso with the pelvis and femurs. The QuickTime video illustrates a human range of motion including flexion, extension, lateral bending, rotation and walking. This model represents the minimum tensegrity structure necessary to create an anatomical form analogous to a human being.
This version of a tensegrity arm demonstrates pronation of the forearm utilizing a basic tensegrity ‘elbow’. The two fingered ‘gripper’ is controlled by two actuator lines which are engaged when the arm extends and continues to operate during pronation. The gripper is built from ‘tensegrity joints’ – all forces are pin loaded with no shear or torque and are mediated by the tension system. This model is controlled by human manipulation but could of course be actuated by computer algorithms.
Combining all of the elements in the above models the complete tensegrity skeleton demonstrates a surprising similarity to a human skeleton. It can walk, sit, stretch, and contort ; most amazing it will stand self supporting with all of the compression elements floating in the web of tension that is woven around it from top to bottom. This model is difficult to make and difficult to balance, but it clearly demonstrates the principle of biotensegrity in its fullest form to date.
36″(H) X 9″(W) X 5″(D)
90cm(H) X 23cm(W) X 13cm(D)