3D Printed Tensegrity Structure

This weekend I built a Tensegrity structure as a demonstration of principles of balancing tension and compression in structures for my course RBT379 - Mechatronics.  I've been fascinated by the aesthetic of these structures - all triangles and edges, but somehow magical as your brain tries to wrap itself around the reasons why the solid supports seem to be floating in air, and the structure is still standing.

I found a couple of excellent pages documenting how the structures work and are assembled - one from the artist Kenneth Snelson explaining the aesthetic inspiration for Tensegrity structures as a kind of 3-dimensional weaving, and another more practical site detailing the construction of a Tensegrity coffee table.

I used the UAT 3D printer to make 12 struts.  You can make these out of much simpler materials (wood, copper, chopsticks, etc), but the Inventor Part design for the struts are provided here. A gallery of the build process and completed 3-level structure (and one rubber-band version) are below.

 I used 20lb test mono-filament fishing line and 2 sets of good smooth-jaw pliers to tie the knots (grip-jaw pliers scar the fishing line, causing breaks after you've carefully tied many little knots), following the guidelines at the Tensegrity coffee table website. If you do this yourself, construct a jig that will allow you to accurately create the tension links at a certain distance (the length of your struts divided by 1.4).

 I built 3 modules, 2 "left-handed" and 1 "right-handed."  To assemble them into the tower, I hooked the struts of one module into the base triangle of tension elements of another, forcing the base triangle into a hexagon.

The resulting structure is surprisingly sturdy, and the fishing line is somewhat transparent, adding to the mystical effect I was trying to emphasize.

Inventor Models

For this semester's Mechatronics course (RBT379) the semester project is to build a self-balancing two-wheeled robot from scratch.  Over the course of the semester we will be designing the frame of the robot, constructing the control schematic, laying out a PCB, and finally programming the micro-controller to self-balance using a PID loop. 

The first part of the semester we're using Autodesk Inventor to design and layout the frame of the robot.  To help with this process I've modeled the major components.  I had a really difficult time finding models of these online, so I'm sharing them with the world:

Standard Servo: Modeled after the Parallax Continuous Rotation Servo
  Inventor Part (*.ipt), Drawing (*.pdf)

Parallax Boe Bot Wheel - Inventor Part (*.ipt), Drawing (*.pdf)

Sharp GP2D12 - Inventor Part (*.ipt), Drawing (*.pdf)

Switched AAx4 Battery Box - Modeled after Jameco PN#216187
Inventor Part (*.ipt), Drawing (*.pdf)

Circuit Board, 80mm x 100mm (Maximum Eagle Free dimension), 4mm holes. 
Inventor Part (*.ipt), Drawing (*.pdf)

SparkFun SEN-09652 Triple Axis Accelerometer Breakout Board
Inventor Part (*.ipt), Drawing (*.pdf)

Most of these I measured by hand, so take the dimensions with a grain of salt, but they should be accurate within a millimeter or so.