Cellular Tensegrity at Burning Man

For Burning Man 2016, we built a 20 foot tall tensegrity structure to represent a cell. Intention is an immersive and interactive tensegrity structure representing the biomechanics of a human cell that treads the intersections of art, engineering, and science. And it is begging to be climbed.

Tensegrities are wonders of art and engineering that are held together entirely by tension and compression. They are responsive while maintaining tremendous structural integrity. We are tensegrities ourselves, built from bones held in compression by tensioned muscles and tendons.

Just as in nature, tensegrities fully utilize all materials, capitalizing on negative space and maximizing efficiency; there is no waste. Intention explores the fundamental building blocks of our bodies by allowing the participant to explore the responsive architecture of tensegrity.

The theme for Burning Man 2016 was DaVinci's workshop. Coincidentally, Da Vinci’s sketches of a reciprocating bridge were some of the first known illustrations of nexorades, the progenitors of tensegrity structures.The outer shell geometry echoes Da Vinci’s De Divina Proportione, and defines the boundary of the cell.

When conceptualizing, we discovered that the principles of tensegrity apply down to the cellular level. Donald Ingber discovered the connection between cell construction and tensegrities. Cells contain a highly complex network of tensioned filaments and compressed microtubules that form eukaryotic cytoskeletal construction. Large struts represent microtubules, and ropes representing filaments that carry tensional forces in the cytoskeleton.

Artistic vision must be reconciled with budget, crew, and schedule constraints. Realistically, a BM project typically goes from concept to execution in under 6 months on a shoestring budget during the evenings after work. It's not uncommon to see partially finished projects out there so it's critical to assess the scope and figure out what's realistic.

Knowing this, we kept it as simple as possible. We picked the form that occupies the most volume for the least complexity; the six bar icosahedron. It's something we've known how to build for two years, so the knew that the main trick would be engineering it for safety and dealing with 20+ foot long struts with limited equipment.

It was a great experience to drive the schedule according to the gantt chart we built (attached), and it was fun to see it evolve over time. The final timeline roughly followed what was outlined.

Grant From Burning Man:

This project was made possible by a grant from the Burning Man Organization. Since we built from last year's tensegrity project, Chirality, we had a previously established relationship, and were ready to apply for a more formal grant. The grant application is a competitive process that requires the following:

• Letter of intent
• Grant application
• Grant award (Contract review & sign)
• Fiscal Sponsorship (or you get the grant taxed as income. We operated under the support of the fabulous Flux Foundation, our big art mentors and teachers)
• Regular updates and communications from their team

Crowdfunding Campaign:

The grant typically does not cover the full costs of the project, so we learned a lot about building a crowdfunding campaign. Not surprisingly, it took more energy than we anticipated. Thanks to Rachel Ciaverella's hard work, we launched an Indiegogo campaign that prevented us from landing in the red.

This is why we all give up our summers and build big art together. Several of us came from last year's crew, but many new members started out as acquaintances and ended up close friends. What formed will last far longer than the sculpture itself, and it was humbling to witness the energy and hard work that came from this crew:

• Katherine Barton
• Jack Kalish
• Rachel Ciavarella
• Johann Karkheck
• Ken Caluwaerts
• Michael Probber
• Sebrand Warren
• Rory Heim
• Lane O'Connor
• Jamie Trowbridge
• Matt Davenport
• Harrison Holland
• Shay Munroe
• Tobey Wilbur
• Rachel Rhodes
• Shelby Clark
• Katie McClung
• Will Buchanan

Swag is a really important part of any project, as it helps bring the team together. And jumpsuits are a lot better than stickers. It was so awesome to see the crew running around in matching jumpsuits with cool custom logos sewn on! Logos were designed by Sebrand and Rachel, and made a pair of dickies coveralls sing. They may not have been the best fitting or thermally efficient desert workwear, but they sure were fun.

We built a maquette using the tensegritoy and some twine. Here you see a single axis between opposite triangular faces, loosely resembling a DNA helix. As you look from the top, there's a beautiful moment of symmetry that lets you stare through the center.

After deciding on a final shape, we built a 1/7 scale model to better understand the construction technique. The pattern was designed with the maximum safe working height first and foremost. Paracord was threaded through holes drilled into the struts.

Our engineering team had many whiteboard sessions to evaluate concepts. We iteratively arrived at a satisfactory design that provided as much redundancy/safety as possible, with the fewest steps.

One of our team members, Ken Caluawerts, was a key contributor to the NASA Tensegrity Robotics Toolkit, so we spent some time to run a simulation with their custom software to try and optimize the structure. The intent was to optimize the components based on the simulation results, but we found a bug in the software, so decided to take a bottom-up approach when sizing the components. This is an area of future interest and potential collaborations.

Tensegrities provide unique engineering challenges and therefore required some straightforward calculations to size every component. The trick in engineering is juggling constraints: getting the optimal mix of cost/weight/safety/schedule, which was done in excel. The following calculations were run and used in determining the final components:

Struts:

• Kinetic & static loading
• Euler buckling
• Bending moment & stress: point load, distributed load

Rigging:

• Factor Of Safety
• Spring constant
• Elastic & constructional stretch
• Thermal expansion
• Routing efficiency & cable deration

After evaluating numerous nucleus designs, we chose a nucleus shape that represents the geometric genome of the tensegrity structure, with connecting filaments tracing the transformation from the underlying shape to tensegrity.

Each midpoint of the edge of the tetrahedron connects to the midpoint of each strut, which is how a tensegrity is generated. We explored running lights nested inside acrylic tubes running along the suspension cables, but decided not to given climbing concerns. The decision turned out to be a good one, as those ropes were commonly used as a handle.

The nucleus was designed by Johann Karkheck. It consisted of a metal tetrahedron frame weldment with the electronics nested inside. We started out doing it in aluminum but found that TIG was beyond our skill level and time for such thin walls, so made it out of EMT conduit. Johann designed a paper blank that wrapped around to get a good fitment on the corners.

The nucleus team was headed by Jack Kalish with power electronics by Ken Caluawerts and programming from Michael Probber.

Once the frame was welded together, it was time to cut & attach the acrylic faces. We used a special plastic mill bit and rivets. The subframe was made from dowels and 3D printed corner caps, with the electronics embedded. Once the electronics were tested, we wrapped the subframe with LEDs and suspended it inside of the frame.

The lights were designed to look similar to cell signal transduction.

Here's what it looked like on the playa:

Once the tubes arrived, it was time to fabricate the struts. Since all holes were CNC cut, it required lots of prep work and welding to get the rings welded in.

Since there were 120 rings to weld, this presented a perfect chance to give volunteers a chance to practice their welding.

This held it all together (literally), so there was no room for error. When you have people climbing your structure, it's necessary to use industry standards and build redundancy into everything. Attached are some resources that were used.

Note: Please consult an engineer with rigging experience if you are going to attempt a climbable tensegrity project.

When assembling 20 foot struts, everything gets a little harder. It was critical to get the right layout since each pole weight about 100 lbs. Wire routing was a bit tricky as well, since it starts to look the same when you're dealing with hundred of feet of the stuff.

It went together well enough for a first attempt, but it was necessary to redo the rigging with a new length scheme. Although it had worked out for smaller models until now, it turns out that routing the lengths according to the nodal distances wasn't the correct approach for this scale. The whole structure was a bit loose, and we had to redo the rigging to compensate for its routing path over the end caps. Overall we held a tolerance of 1/8" throughout, which worked well.

After some minor overloading fiascos, we shed some weight and made it out there without a hitch (pun intended). The trailer used was a boat trailer and the struts formed the base which everything piled onto.

After check-in, Art Support Services takes you to your placed location by way of GPS. Pretty neat to know that your location is marked with CD and pink tassles, surrounded by desert.

The solar design was led by Jamie Trowbridge, and was designed for two days runtime at maximum power. This gave us a good factor of safety given the constant need to wipe the panels from dust. Towards the endof the event we discovered that low pitch panels create a dust vortex that traps all sorts of debris from the playa. It completely filled underneath with dust deposited from windstorms.

The batteries and charge controllers lived in a lockable box that also contained brains of the sculpture.

Erection was pretty straightforward. We lifted the poles partially to aid in assembly.

Wait out the heat of the day, and take regular breaks. Drink lots of cold things.

That night we hung the nucleus and hooked up the electronics. It provided significant satisfaction by firing it up for the first time and seeing it all work.

One of the best parts about build week is that you can camp on the open playa before the chaos ensues. Five of us put hammocks up and napped in it overnight. We were gently rocked to sleep until a new visitor came by, or the cold set in.

The responsive architecture is the core concept of the piece; watch as we play:

Once the piece is finished, it's time to go to Burning Man. We had an amazing time venturing out as a group.

You're probably wondering why we didn't include the ropes. We made a suspended flute system by accident. Anytime the wind blew it sounded like a symphony of bottles in the wind, at a chest throbbing resonance.

During build, we kept wondering what that loud noise was, and assumed it was from another art piece. To our surprise, someone named Mustang from Art Support Services pointed out that it was us.

We decided to not put the ropes in because we liked it so much. Partly from embracing the discovery, but also for safety considerations. If we put more handholds on the piece, injuries could occur from unskilled climbers.

An important step. Our friend Taylor and his crew were still working on their piece Enunciation, a parametric structure designed in Grasshopper. We made sure to drop by and help them in the little ways we could; tools, hot gluing, wire stripping, caffeine, and brillo pad scrubbing. It's a rewarding part of the journey and ensures you stay connected with the larger community of artists doing challenging things in the desert.

We gathered at sunset to celebrate the completion of the piece, and invited our friends. It was a magical moment.

The sculpture went down without a hitch. Leave No Trace is in full effect here, down to the stray human hairs that caught in our solar panel dust trap.