TV

I recently appeared on a television show on the Discovery Channel called The Big Brain Theory, which had 10 engineers solve 8 extremely hard engineering challenges in very short periods of time. I had a blast participating in the type of design/build show I used to love watching, and I’m hoping I’ll end up on TV again sooner rather than later!

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Big Brain Theory Overview

In early 2012, I decided to apply for a show being cast by Pilgrim Studios for the Discovery Channel called Top Engineer (a name which was later changed to The Big Brain Theory). The show was being billed as a new kind of design/build competition, in the style of Junkyard Wars (one of the shows I absolutely adored as a kid), and I couldn’t resist. I sent in an application video, got a call back, went to an in-person audition in L.A., and became one of 10 contestants, out of around 1,000 applicants who were asked to submit more information.

I then mysteriously disappeared from Boston for 7 weeks, and during that time filmed 8 episodes of The Big Brain Theory. The show followed 10 engineers through 8 different extremely difficult engineering challenges; the engineers would be split up into 2 teams, and given between 3 and 5 days to build a device in response to a stated challenge. These challenges included shooting a missile out of the sky, stopping a speeding car without damaging it, building a portable and deployable shelter that could withstand extreme weather events, and keeping a 160-pound “bomb” from exploding in a head-on collision, just to name a few.

I had the time of my life working on these challenges, though it was also one of the most stressful experiences of my life. I really hope that it inspires kids and adults alike to pursue their interests in engineering, math, and science, the way that shows like Junkyard Wars, Battlebots, Bill Nye the Science Guy and others inspired me as a kid. Check out each episode of the show and my play-by-play review of them here.

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TBBT: Crashing Trucks

The first challenge of The Big Brain Theory was a modification of the classic ‘egg drop’ engineering challenge; how do you protect a sensitive payload (such as an egg) from a sudden impact? In our case, our ‘sensitive payload’ was a 160 pound box full of explosives, and you had to keep the box from experiencing too high a G-force in a head-on collision between two pickup trucks. How cool is that? Check out the full episode here:

The answer to this challenge (and indeed, just about any challenge where gentle deceleration is called for) is simple: the farther the payload has to decelerate, the lower the force required to bring it to a full stop. The equation for Work, which is a measure of how much energy you can impart on an object, is simply Force times Distance. The greater the Distance the object travels, the less Force required to stop it. In this case, the G-force on the package needed to be less than 25; that comes out to the force needing to be less than 4,000 pounds at all times. Easy, right? The question then is, how do you successfully guide a 160-pound package, and how do you stop it from moving at 35 miles per hour?

Let’s start with a little context to this episode. You know the shot where you see us all standing in an arc around Kal Penn? That was the first time we had spoken to each other. We had been on total lockdown up until the point when the cameras started rolling. Immediately after being introduced to everyone, two trucks exploded in the background, and away we went! None of us had any idea what to expect from our teammates, the shops, or the show. We arrived at the shops not knowing what tools would be present, what tooling we had on hand, or what raw materials we had access to. In fact, a good chunk of the first day was simply organizing all of our tools and ordering more tooling to fill in large gaps in capabilities. That said, on to the challenge.

This challenge saw me on the Blue team with Joe Caravella, Alison Wong, Tom Johnson, and Joel Ifill. The first thing that happened, as the show points out, is that Joe opened up the design space to a democratic process. As you’ll soon see, I took issue with this – we had 36 hours to build a contraption that could passively apply equal to or less than 4,000 pounds of force to a 160-pound box over a significant distance, working with 4 people we’d never met and in a shop environment we hadn’t used before. We immediately went in 5 different directions, and spent the better part of the first day arguing about ways of stopping the box (though, to be fair, we decided early about what type of rail system, sled system, and rail mounting that we wanted – more on that later). Eventually, I suggested a solution that the team found palatable.

Piston Rails

The suggested solution was stopping the package with a gigantic set of pneumatic cylinders. The idea was that the pistons would compress air in their extension chambers, and use that compressed air to generate a force to slow the package down. They would essentially be used as large gas springs, with an open vent in the back of their chambers to allow air to leak out. In the show’s animation, you’ll also note a second layer of die springs that suspended the package in its trolley to prevent sudden impacts from imparting G-forces. We abandoned this fairly early as being too complex to make work.

To make a very long story short, the pistons as presented probably weren’t going to work without significantly more tuning and analysis. For one thing, gas springs like this have an increasing spring constant (as opposed to a coil spring, which has a fixed spring constant); at the start of their travel, the pistons wouldn’t be creating much pressure, and at the end of their travel, they might be at pressures high enough to rupture the cylinder walls. This type of behavior meant that if we didn’t size the system correctly and pick an appropriately sized air vent, the pistons could easily either not apply enough force to stop the package in the first place, or simply explode. See the chart below for a visualization of increasing versus constant spring values; our pistons definitely fell into the ‘high volume air shock’ regime.

Air Shock Visualization

What happened next is that we essentially spent a ton of time trying to figure out how the system would behave. I can safely say that a) Joe was by far the most qualified of us to do the mathematical analysis, b) there wasn’t enough time in the entire challenge to create a good model no matter who was doing it, and c) characterizing the volumetric flow and resulting pressure out of these pistons, under these conditions, is extremely difficult to do. Air is compressible, its flow is hard to characterize, and it behaves very differently given slight changes in environmental conditions – check out the difference between adiabatic expansion and isothermal expansion if you want to get an idea of what I’m talking about. After a day and night of coming up with the idea and trying to characterize it to no avail, we learned that the cylinders had been held up in shipping and wouldn’t arrive until after the challenge was over anyway! That was the final nail in the coffin, and we moved on.

Plan B was to replace the pistons with a brake and spring system that tied to our existing rails (note: the show only discussed the brake system). We designed a floating brake system that could pivot to follow the rails, was lined with standard brake material, and had four independent shoes (two per brake) that were each sprung by heavy-duty die springs. These engaged with the C-channel on the outside of our rail structure as the sled slid down. In addition, we designed for a significant latex spring system to add a little extra stopping power; for those that are curious, we actually tuned the spring system to be critically damped with the brakes.

Brake RailsAs far as the rail, sled, and rail mounting system were concerned, we had a fairly good idea of what we wanted from relatively early on. The most robust rails we could think of were two heavy-gauge L-brackets turned inwards, with a trolley mounted on rollers between them. The advantage of the system was that it was extremely rigid, and it completely prevented the trolley from moving from side to side, up and down, or twisting. The downside, of course, was that it was complex and took a long time to build.

Mounting the rails proved to be its own engineering challenge. We were worried that if we simply welded the rails to the frame of the truck, they would twist and distort in the crash, and somehow prevent the trolley from moving. As a result, we took care in designing the rails to mount as a statically determinate beam; the front of the rails were on pivots that were welded to the truck bed, and the rear section of rails were attached via pegs in slots. The net result was that the truck could crumple, bend, or twist, and the rails still had enough freedom of movement to stay straight. The picture below illustrates the setup; the left-hand attachment is a pivot, and the right-hand attachment is both a pivot and a side-to-side slider.

Simple Beam

Now, all that said, we didn’t finish on time. A little past the halfway mark of the build, I noticed that we just weren’t getting things done. We were still going off in many different directions – Joel was welding frames together, Tom was teaching Alison how to use a number of the tools in the shop (which, while noble, sank a lot of time unnecessarily), and Joe tended to be running around between a number of different tasks and states of mind. Metal was being cut in inefficient order that left Tom and Joel unable to keep working at various points, and it became pretty clear that at the rate we were moving the project wasn’t going to get done. I got pretty frustrated, snapped, and took over the build by handing out jobs and specifically ordering all work. After I told everyone to shut up and get to work, the teaching stopped, cuts were ordered so that Joel and Tom could stay productive with their tasks, and we started moving pretty quickly through the build.

When the buzzer sounded, we had an attached rail system with a functional trolley and one working brake; we still needed to weld on one completed brake assembly, tighten the brake springs appropriately, attach a lid to the box with four sections of all-thread, and attach a single nut to 5 or 6 spring assemblies. As Tom Johnson put it, the system very likely would’ve worked had we had another 10 more minutes of assembly time. Oh well!

When game day came, however, both trucks exploded. Having seen Red Team’s truck, we were initially surprised – it seemed fairly robust, all things considered. When we looked closer, however, there were a couple of really critical design errors which seemed to doom it. The show mentioned the brakes being “too tight” as the ultimate downfall of the Red Team – that was a simplified and, I believe, slightly inaccurate assessment of the cause.Red Team Bent Truck

The first and potentially largest error was that of material selection. When we designed our brakes, we used easily-sourced brake liner and bolted it to steel. The Red Team decided to create their own brake pads from scratch using aluminum blocks, under the theory that a softer metal will wear against a harder metal and serve as a functional slide. In theory, this tends to work out (especially with brass and bronze acting as the softer material), but the caveat is that they chose aluminum for their brake pads; aluminum, unfortunately, has very low surface energy and as a result readily undergoes galling when slid across any other material. Galling increases frictional forces very, very quickly, and could easily account for the sudden stop their package experienced after starting to move.

The second error was that of rail mounting. For whatever reason, the Red Team decided to weld the front supports of their rails to the crumple zone of the pickup truck. In addition, they welded the rails directly to their supports, which meant that when the supports moved in the collision, the rails likely underwent buckling because there was no way for them to pivot out of the way – this would have warped the rails and potentially either squeezed the trolley or caused the rails to change cross-section (and therefore dramatically change the friction in the system). You can see this bending in the screenshot above, and you can see that the package stopped right at the bend in the rails.

All in all, however, this was a great first challenge. It built on a type of challenge we were all familiar with, it called for us to build relatively straightforward and simple systems, and it left us more than enough rope to hang ourselves in the end. If we had to do it again, I think the simplest, most effective system would likely be one where we have rails designed and mounted similarly to the rails we had on the Blue team, with a simpler trolley (perhaps with sliding contact instead of rollers), connected to a common, off-the-shelf disc brake spooling out cable to decelerate the package.

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TBBT: Missile Defense

The second challenge of The Big Brain Theory was a missile defense problem – given 5 days to build, and $20,000, how do you shoot a 20 pound foam projectile out of the air before it explodes, spraying goo all over you and your team in a steel bunker? Check out two ideas here:

 

Interestingly, they introduce this challenge by mentioning the Star Wars program, an initiative to create a national missile defense system that would protect against incoming ICBMs. In its time, the program was considered completely unrealistic and a near-total failure. Foreshadowing, much?

Before I get into the engineering, I want to take a moment to address what this episode didn’t show, and by and large, didn’t even allude to. At face value, this episode paints me as the person who did all of the design for the entire structure, who ham-handedly forced everyone into fabrication and dull layout roles, and who is entirely to blame for the thing not working. What they don’t show is the fact that everyone laughed and exclaimed when they saw the design I proposed to the judges, and the group was consulted and agreed that we should move forward with the propeller design together – even given a relatively low probability that it would work. What’s also not shown is the division of engineering and design that did occur; Amy and Alison took on design of the release mechanism, pan joint, and base frame, Joel prototyped the triangular head section and determined the optimal size of the propellers given our construction, and Tom took on the full design of the ammunition (including the ultimate selection of propeller blades). My role ended up being designing the powertrain and drive, spec-ing out and installing the pan/tilt actuators, integrating everyone’s design into one functional system, producing drawings that we could use for fabrication, and keeping everyone on-task.

The show also didn’t show the voting process (where we used decision matrices to tally everyone’s reactions, and all voted as a team) that we used as a group to select Tom’s proposal of windmill propellers over airboat, plane, or fan propellers. It didn’t show me reacting to Amy’s request for more work by, in fact, giving her more design work to do (something she talks about here). It didn’t show us reviewing Amy and Alison’s release mechanism design and approving it as a group. It didn’t show just about everyone contributing to the fabrication (including yours truly, though I certainly did less than others). One final, really sad thing it didn’t show is the team being excited to work on the project in the first place! We were trying something really hard, we were doing something creative and off the beaten path, we were generally getting along and being productive, and we were having fun. None of that came through, sadly – I guess it doesn’t make for a good story. Do those capes, hats, goggles and smiles we were wearing on competition day look like they came from a team that was full of drama, or that didn’t like the process?

Blue Team Outfits

What it did show was me coming up with a wacky, off-the-wall idea in the first place, that was significantly different from any other proposal that was made in the blueprint challenge, and being chosen to lead a team because of proposing that wacky idea. Given that the goal of the competition, repeated again and again by Kal Penn, Mark Fuller and Christine Gulbranson, was to find the most innovative engineering in America, I didn’t feel bad about proposing something out of left field. The episode also showed me insisting on a structure for decision-making and design, and insisting on a process to replace the chaos that had been the previous challenge. This, by necessity, meant that everyone had less input, but it also meant that we got things done under budget and ahead of schedule. I’ll definitely admit I was pushy in the introduction to the challenge, unreasonably condescending in a couple of moments, and unequally distributing some of the work, and for that I apologize. I don’t think it deserved the one-sided portrayal of this particular episode, though.

But now, on to the engineering. We ended up building something that looked like this:

Whirligig Launcher

The fundamental idea was to spin a propeller on a shaft until it produced enough lift to fire itself, and let the propeller go once the missile was in range – essentially, creating a giant hand helicopter toy. Since we knew exactly where the cannon would be, and more or less what the ballistic trajectory of the missile would be, all we needed to do was sweep that area of space thoroughly and make sure nothing could get through (which is exactly what ended up happening with both of Red Team’s ‘successful’ shots).

Hand Helicopter

Of course, it’s never that easy. The device never fired, as shown on the show. The judges believed that the propeller ammunition was simply too heavy; while that certainly could have contributed, the Blue Team thought it was much more likely to be due to the release mechanism not letting go, and to a lesser extent too much friction building up in the drive mechanism. We based this assumption on test fires (that weren’t shown) where we demonstrated enough lift to stretch an 1/8″ steel safety cable that was anchoring the ammo to the launcher by half an inch or more – enough to separate the propeller round from the hex that drove it at its base. I want to talk through some of the engineering decisions that we made that led us to this belief, and why we made them the way that we did.

One of the first major decisions was to decide on a type of propeller blade to power the system. Tom gladly took the design of the ammunition on, and came up with a number of options. The first option was to use a set of airboat propellers; these would certainly generate all the force we would need, and were incredibly robust. Unfortunately, they cost over $1,500 for a set, and all the suppliers we could find wouldn’t guarantee that they could get us a single one within the time frame we needed – much less the 5 that we were asking for. The same story was true for small plane propellers – they were extremely expensive, and likely not available. At one point we even considered buying Big Ass Fans (not even kidding about the name) and stealing their blade sets, but got extremely concerned about their weight, resulting kinetic energy at top speed (we calculated that one metal blade flying off at full speed would go straight through one side of the Red Team’s bunker and out the other) and similar cost to regular propellers. The cheapest, safest, most readily available propellers we could find were windmill turbine blades; they were made of fiberglass, we could have dozens by the next day, and they only cost $300 a set. Unfortunately, they’re not particularly designed to produce thrust; in the end, Tom had to modify them by changing their camber angle with angled shims. We’re sure this reduced our efficiency, but as I said, we did prove to have a significant amount of lift available.

The next big hurdle we faced was designing a release mechanism, also known as an escapement. How do you hold on to this propeller when you’re spinning it up, but release it at just the perfect time? Amy and Alison took the lead in designing this portion of the project, and came up with a design the whole team thought was reasonable in the brief design review we had time for; they proposed a set of jaws, geared together, that would clamp down on a ball bearing on the ammunition shaft and spring open when a pin was pulled.

Release Mechanism Unfortunately, this design is one of the least effective release mechanisms we could have implemented – the springs attempting to open the jaws are actively fighting the friction from the side of the bearing pushing against them, due to the force of lift from the propeller, and the more force we put on the propeller, the worse the problem gets. Worse than that, though, none of us really caught on to this problem until it was too late; we had all looked at the design, we all gave it the thumbs up, and it got made. I don’t blame Amy and Alison for it in any way, since we all looked at the design and gave it a thumbs up without much hesitation.

All that said, the design certainly had other problems. The shaft was extremely long, and ran the risk of torquing inside the barrel before it fully released. The rounds were, as mentioned by the judges, relatively heavy. The propeller shaft was driven from behind by a hex feature inside a socket, and it’s possible that a significant amount of friction was building up in that interface and in the sleeve itself. We managed to trip the generator by ramping the motor speed up too quickly, a problem which had never happened before in our testing. If I had to do this particular design again, I’d make a number of changes to address all these little problems, including:

  • Decreasing the shaft length and proportionally decreasing the propeller size, to cut down on balancing issues, reduce weight, and potential torquing inside the sleeve.
  • Driving the rotation of the propeller with spur gears located near the front, to allow for a much lower resistance to linear motion.
  • Attaching a magnet to the back of the shaft on a bearing, and holding the shaft in place with a strong electromagnet on the chassis, so that we would have an electric release mechanism with much less potential for binding.
  • Using proper lift-generating blades such as airboat or propeller blades.
  • Properly programming a slower ramp into the motor acceleration to reduce current draw.
  • Potentially fire the propeller by means other than lift, so that the spinning blades could still effectively sweep the target area without being relied upon for force generation.

Of course, if I had to propose a design from scratch all over again (and if I had known the budget was $20,000 in the first place), I might just propose buying an army of baseball pitching machines and building pan/tilt mechanisms and control systems for them.

I do want to make one final note, though this has gotten long – I do want to talk briefly about Joel. It’s true that the ultimate, top-level design of the propeller-firing device was mine, and I accept responsibility for that. It was an ungainly, unlikely design, but if it worked it would’ve been one of the first devices of its kind to ever be on television. It was different, it was a difficult engineering challenge, and it was fun to conceptualize and work on, but in the end, it wasn’t a great answer. That said, I think the big, un-aired reason the team didn’t universally suggest throwing me out was because the build ran so smoothly – we got things done as a group, we voted on details of design, we finished 3 hours ahead of schedule, and people had fun while doing it. It certainly sucked to lose, but the process we went through was sane and relatively free of drama. The reason I mentioned Joel explicitly at the end was because, of all the team members on Blue Team, he alone carried a contagious bad attitude much of the time, and a disregard for the quality of the work he wasn’t excited by, which actively hampered the team’s progress. That’s not to say that Joel slacked off, or didn’t do a great job in certain key ways – the welding he did on the main shaft sleeve was amazing, for instance, and I’m not sure any of us could have pulled it off without him. It was just that, when it came time to pick someone, he was the person that I (and other members of the team) felt was the weakest for occasional, very specific anti-social and anti-productive behavior. Honestly, I like Joel as a person – I think he’s hilarious, and he has very solid design insight to offer. In this case, though, he just wasn’t acting as the team player we needed him to be.

I will say that one of the only regrets I have from this whole competition show is not seeing this thing fly. I’ve often considered redesigning and rebuilding it, if only to watch it launch.

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TBBT: Portable Shelters

The third challenge of The Big Brain Theory required the teams to build a man-portable (i.e., something that could be carried by one person in a small bag) shelter that could be set up in 5 minutes to ‘survive the elements’ – namely, 200 mile-an-hour winds, flames from a flamethrower, and a burst of water from a giant water cannon. Check out the full episode here.

MY BLUEPRINT CHALLENGE

The opening of this episode took place in a fire department training ground. They had a portable jet engine, a gimbaled flamethrower, and a gigantic, fire-hose fed, pneumatic water cannon pointed at a pre-fab shed they built on a concrete platform. The first element they showed us was ‘wind’; the jet engine spooling up to top speed. Almost nothing happened to the shed, other than the plastic chairs and standing umbrella scooting out of the way. The second element they showed us was ‘fire’, where they shot a relatively cold (the more red and smoky a flame, the colder it is) flame into the shed for 10-15 seconds. This scorched the shed, and started a small fire, but otherwise had no effect. They then demonstrated ‘water’, and brought out one of WET Design’s custom waterjets pointed sideways. This blew both the front and the back off of the shed, much to our surprise. We then proceeded to the Blueprint challenge.

At this point, they had simply told us the shelter needed to be moveable and deployable by a single person, and hadn’t elaborated further. I then proceeded to design a modified, armored hand truck that could be quickly wheeled somewhere and flipped over, and would form a hardened carapace for the wearer when on the ground. This, I reasoned, could be extremely well-engineered and relatively light-weight, and would offer rigid protection against the most damaging element by far – the water cannon.

Episode 3 Blueprint

Unfortunately, the judges chose to inform us that we needed to both a) fit in a small duffel bag and b) offer equal 360 degree protection after the Blueprint challenge was over. These extra requirements excluded everyone’s designs except for Amy’s and Alison’s, and was a point of significant frustration for most of the rest of the cast. In engineering practice, you need to know your project requirements upfront to be able to design a good product – in this particular case, we weren’t granted that.

TEAM PICKS

Based on her frustrating experience with my leadership in Challenge 2, Amy picked me last. I admired her ability to put that experience behind her and pick me for her team again, and used this as an opportunity to switch into a strong design role.

IDEATION

Amy started the ideation and brainstorming process in her characteristic way, by having everyone draw their ideas for shelters on the boards. In this particular instance, it really felt like a second ‘Blueprint challenge’, because the requirement of the duffel bag was so limiting that nobody felt comfortable with their original idea. Interestingly, Amy almost immediately discarded her own turtle shell idea as infeasible due to our inability to work with inflatable devices in a timely fashion, and put the onus on the team to come up with a different solution.

Truth be told, I didn’t really participate in this whiteboard process, as I was thinking in overdrive about how the challenge worked with new restrictions. In this case, we were designing one component – a deployable structure that had to collapse to the volume of a bag. Instead of drawing on a whiteboard, I created to-scale models of a human being in fetal position (the smallest position configuration) and the bag itself. I then attacked the problem by creating cardboard sketch models, using the physical prototype volumes as a basis for the design. My rule was simple – if it didn’t work in cardboard, and didn’t fit in a to-scale bag, it wasn’t a reasonable design, period. I ignored the whiteboard as a medium, by and large, because I feel like drawings on whiteboards aren’t to-scale and aren’t good representations of what is physically possible – both of which are extremely dangerous pitfalls to succumb to in a 3-day design challenge. This process is how I arrived at the design of the folding geometric structure that was adopted as the team’s design.

Episode 3 Cardboard Sketch Model

DESIGN

The final design required a person in fetal position to hang from a lid on this conical figure (thus significantly increasing the mass of the device, which was severely limited by the portability requirement), covered in a fireproof and heat resistant shroud.

Episode 3 Design

The biggest challenge with this particular design was that the hinges had to be able to a) fold more than 180 degrees, b) stack as flat as the panels themselves, and c) weigh almost nothing – as we were going to need upwards of 50 linear feet worth of hinged surface. Conventional pin-based door and piano hinges were immediately discarded between those three requirements, and we had to improvise. I proposed a design for rolling band hinges (where two rounded edges roll off of each other, and are prevented from separating by steel bands – offering a full 360 degree range of motion for no weight), and we built up a full hinge out of plywood and regular printer paper for testing. It’s worth noting that even when the bands were made of paper and stuck together with spray adhesive, it was impossible to rip the panels apart by hand – how cool is that?

Rolling Band Prototype

In the final design, the panels themselves were made of 3/8″ thick Lexan – an incredibly tough, thermally insulating, transparent polycarbonate material frequently used to make bulletproof glass, shield Battlebots from weapons, and hold back the weight of water in aquariums. It was actually our second choice for panel material – Corey and I attempted to design honeycomb panels (featuring an aluminum honeycomb glued to top and bottom sheets), but couldn’t find raw materials that were both cheap enough and light enough to substitute for the plastic in the time we had. The panel thickness was designed to stand up to the waterjet cannon hitting dead center, which we estimated to be a continuous load of up to 1,600 pounds of force.

The panels were covered by high-temperature silica cloth, the most-insulating fabric material I could find on McMaster-Carr, our industrial supplier of choice due to their same-day turnaround. The cloth was so effective that I could hold a MAPP gas torch against one side of the fabric, and not feel anything more than general warmth on the other side with my bare hand. The only significant downside was that it was almost impossible to sew, as the fibers didn’t respond well to thin thread – in the end, Amy devised a method of installing large grommets in the fabric in order to keep it cohesive. It was ugly, but very effective.

One final addition to the design was made in the second half of Day 2; Dan suggested we add an underlying metal frame that would be responsible for keeping the panels a certain distance apart, so that the assembly wouldn’t collapse in on itself when hit with water. This was deemed to be a good addition to the design, and Dan spent the last day and a half making this system with Amy’s help.

BUILD

This is the first challenge where we started to make significant use of WET Design’s automated production capabilities – a resource we had access to that hasn’t been publicized much on the show. I designed the structure to be cut out by CNC waterjet cutters and metal-cutting lasercutters, so we essentially just shipped them full 4′x8′ sheets of Lexan and stainless steel and they shipped us cut-out panels and hinges some time later. While we were waiting for these parts to be cut for us, we decided to build a full-scale wooden mockup using the wood panels, paper hinges and spray adhesive.

Prototype Shelter

The mockup gave us some early test time with the design, allowed us to make sure it could be packed into the duffel bag, and verified that we could fit a human being inside once deployed. On top of all that, it won us major points with the judges. Soon afterwards, we received our raw panels and bands, and began the production process in earnest.

Episode 3 Bare Panels

Each panel needed to have both sides rounded (by a specialized rounding end mill), needed significant sanding, cleaning and scoring at each hinge site (as we were both screwing them down and gluing them together with JB Weld, per Corey’s suggestion), needed 30 waterjet-cut holes countersunk, and needed 30 self-tapping screws drilled into them on two sides. With 16 panels total, this came out to a huge amount of mind-numbing work that had to be done in a very particular order. We formed an assembly line and got to work, doing little else on Day 2. We were done with panels and their assembly by the middle of Day 3, and spent the rest of Day 3 working on a lid, creating an underlying metal structure, making final adjustments to the overlying fabric, and arguing.

NEEDLESS CONFLICT

At some point in Day 3, Dan got it in his head that we must not be allowed to slip on the concrete while being hit by a giant cannon. Corey argued (and backed up with simple math) that we would be hit with far more force by trying to stay in one place, than if we simply allowed ourselves to slide. Dan wouldn’t stop screaming and yelling (even uttering the ridiculous absolute statement ‘if we don’t add neoprene, it will fail’ – since when is anything ever so certain?) until the four of us gave up and installed the neoprene strips on the underside of the metal frame. This is the one point in the competition where I really felt Amy could’ve done a better job stepping up and making the correct engineering decision that was desired by most of her team; otherwise, she had been a fine leader throughout the challenge. I will also say that Corey was unwilling to let this issue go until I told him that we would either win, or we would kick Dan off the team for being so illogical and needlessly combative if we lost.

Episode 3 Needless Confrontation

I do want to take a moment to say that up to this point, this was the most inappropriate behavior I’d ever experienced in any engineering team setting, in my entire life. For a team member to get defensive about a design feature to the point of yelling, screaming, and utterly refusing to compromise is inexcusable. I had been giving Dan the benefit of the doubt up to this point, but this started me on a path of seriously doubting his capabilities as an engineer.

PERFORMANCE

All in all, we did fairly well. The shelter assembled quickly without a hitch. We survived the wind without a second thought (though the silica fabric took a little more of a beating than we expected). We actually got blasted with the flamethrower 4 times, from 2 different directions, because wind kept interfering with the blasts – regardless, the highest temperature inside our shelter was under 100 degrees Fahrenheit. Then, of course, we got hit by the water cannon.

Episode 3 Water Blast

The hinges failed between two of the panels, where they got hit by the cannon. It appeared that both the JB Weld failed, and the screws we were using ripped through the edges of the steel sheets.

Never forget – 2 out of 3 dummies prefer Red Team.

POST MORTEM

At the end of the episode, the announcer suggests that our screws were small and we had no washers on them. This is true – we used countersunk screws, which have small heads by default and don’t generally allow for washers. I imagine that by sinking the countersunk screws into the flat steel bands, we created stress concentrations that would allow for tears to propagate fairly easily to the edges of the material. I’m surprised the glue didn’t hold better, however – to be honest, we saw the glue as the primary attachment mechanism, and the screws as a backup. Mark suggests in his Blueprint breakdown that we could have spaced the screws further away from the edge of the bands, but we already had 3/4″ or more material there; I’m unconvinced adding more would’ve significantly improved our strength.

If we had to do it again, I think I would’ve wanted to switch from steel sheets to nylon webbing with built-in grommets for the bands. Nylon is generally much more resilient than steel, and much less prone to tearing in that form factor. I don’t think we could have easily ‘added washers’, as the announcer implied, because the panels would then not fold flat and the design wouldn’t have fit in the bag. I would’ve also wanted to switch from the neoprene rubber to a slick plastic that would’ve encouraged sliding (or perhaps a combination of slick plastic and neoprene, to encourage pivoting out of the way of the stream of water), so that we could get out of the way of the water faster and absorb much less force.

Episode 4 Thumbnail

TBBT: Triathlabots

The fourth episode of The Big Brain Theory asked teams to develop robots that could compete in three athletic events; a 100-meter dash, a javelin toss, and a standing long jump. The dash and the javelin toss were won by the team that went the fastest and furthest, but the javelin toss was governed by who tossed the javelin closest to the Olympic record. You can catch the full episode here.

MY BLUEPRINT CHALLENGE

I started building robots in freshman year of high school by participating in the US FIRST competition, a yearly competition where teams get a big kit of parts and 6 weeks to build a 130-pound robot. This particular athletic event felt a lot like building a FIRST robot; those robots are typically required to do a number of difficult tasks, and combine those tasks into one chassis. My immediate answer to this challenge was to start thinking about how I built those robots, and how I build most robots these days; let’s build it from scratch!

Episode 4 Blueprint

I provided a loosely sketched concept to the judges (with a fixed javelin position fired by stored energy, a fixed high-pressure pneumatic piston to launch the robot, and gigantic outrunner brushless motors to power the drivetrain), and focused on the most important qualities of that robot; that it have an extremely high power-to-weight ratio for all of its subsystems, that it push through its center of mass with the jumping piston so it didn’t spin out of control in mid-air, and that it have as few moving parts as possible to increase system robustness.

None of this was particularly clever; it was simply an attempt to design the most robust, highest-performance robot possible. In my opinion, it lost out because it wasn’t all that innovative, it was just sound engineering; this develops into a running theme throughout the series.

One quick note – it wasn’t clear from the way the challenge was described if we were supposed to imitate humans or simply do similar types of tasks. That’s why you see Eric and Amy proposing legged vehicles that were generally not going to be competitive against wheeled vehicles; it wasn’t clear which way the judges were going to decide. What was also not clear (and announced later) was that the jumping element of the competition allowed for a secondary robot that was 25% of the mass of the full vehicle to detach from the main system, in order to jump on its own. These are both more instances in which we didn’t feel like we had all the information we needed from the start to come up with good designs, leading to more frustration.

TEAM PICKS

I was glad to be picked first for a team, but I was incredibly anxious about working with Dan as a team leader. Most of Challenge 3 had been fairly calm, but towards the end he had exploded in the same way he had blown up in every previous challenge, making me wary of working with him in general. That said, I hadn’t seen him in a leadership role, so I was willing to give him the benefit of the doubt going into it. I was excited to be working with Amy (another US FIRST veteran), as we had started seeing eye to eye over the course of the last challenge and shared a lot of fabrication and robot-building experience.

DESIGN

Our brainstorming phase was nowhere near as cohesive as they made it seem in this episode. Let’s review the major subsystems, and talk through all of the different questions we had to address.

Episode 4 Ideation

We approached the ideation process in a way similar to how Amy tended to handle the start of a challenge – by drawing everyone’s ideas on the board. I had had a bit more time to think about a design after feeling like the judges weren’t interested in the fully custom system, so I proposed simplifying the design process by buying a vehicle we could modify – a giant-scale remote control car. We agreed on this fairly quickly, and I immediately went to a hobby store to purchase an electric 1/5th Scale HPI Baja (in addition to all the RC electronics we would need to create the rest of the robot), a 4-wheel-drive monster of an RC truck that weighed 20 pounds and could hit speeds as high as 60 miles per hour.

We then proceeded to spend a lot of time discussing strategies for firing the javelin. The javelin in question weighed two pounds, and we had to launch it as close to the Olympic world record distance as possible (which I believe was around 300 feet). We immediately ran into a problem when we realized that the size of the RC car severely constrained the potential size of the javelin launcher, which meant that we had to use a very energy-dense launching system. We thought about an air cannon (similar to Blue Team’s design) briefly, but discarded it due to weight concerns. The two major ideas boiled down to a compound bow suggested by Joel and a latex tubing-based launcher that I suggested.

Compound Bow Launcher

I was initially enthusiastic about the idea of converting a standard bow into a launcher, because it seemed very well tuned for what we wanted to do. Upon calling an archery store and speaking to a world-class archer and bow designer, however, we were informed over the phone that such a launcher would self destruct within just a few shots. The largest compound bow available was designed to fire no more than 150-grain arrows (which themselves are considered heavy, and generally only designed for crossbows), which weigh approximately .021 pounds. We were trying to fire a 14,000-grain javelin. Heedless of the advice of professionals and several team members, Dan insisted that we spend $1,000, hours of our time to pick it up, and yet more hours of our time to test it just to make sure. By comparison, two latex tubes that we used to compare launchers shot the javelin 30 feet farther on their own in our test runs. The compound bow eventually self-destructed due to test fires before the competition day, making the question of launcher type a moot point.

Episode 4 Javelin Launcher

The final question came down to how to jump. During the Blueprint Challenge, we all believed the entire robot had to jump. The judges later clarified that a smaller, jumping robot that weighed 25% of the mass of the larger robot, could detach and jump on its own. We came up with three major ideas; jump the entire RC car with a high-pressure pneumatic system, jump a smaller car with a spring-based system, or jump a smaller car by detonating an airbag (suggested by Joel). Everyone, including myself, loved the airbag idea – unfortunately, it was shot down by the Powers That Be because it was technically an explosive. This left us to decide between a high-pressure pneumatic system that would jump the large car, and jumping a small car with a spring system.

Jumping Car

Dan and I had discussed some of the robots I had worked on and seen at Boston Dynamics, that had similar capabilities to what we were attempting to do. As a result, he wanted me to create a high-pressure pneumatic system that would allow us to jump the whole robot, and told me as much at the outset of the competition. Unfortunately, we soon hit a major snag – this particular competition started on a Friday, and ended on a Monday. As a result, every single industrial supplier I used on a regular basis (excluding standard industrial suppliers like McMaster and Grainger, which don’t carry the parts I was looking for) was closed for overnight shipping to California before we could even come up with a design. As soon as I realized this, I told Dan that I couldn’t source the parts in time, and we needed to switch designs. He insisted that I keep pushing on the pneumatic design regardless of how many times I let him know I couldn’t get the parts. Eventually, after two days of searching and calling any store I could find that was open on a Saturday (including Lowlife Hydraulics, a shop that specialized in making lowrider cars jump up to 10 feet in the air with hydraulic pistons!), I cobbled together a design that mixed paintball air storage tanks, single-acting hydraulic cylinders, Chinese knockoff dump valves, and hydraulic fittings and hoses to create an 800 psi pneumatic jumping system. I’m not even going to post a systems diagram here – it was a terrifyingly dangerous mixture of components that only went together out of desperation and a lack of the proper suppliers. It didn’t work too well (it lacked an accumulator, and relied on the flow-limited outlet port of the paintball tank to supply air), and wouldn’t integrate into the existing design anyway. By the time Dan was finally ready to scrap the idea and switch to a spring-loaded jumping robot, we only had one day left in the build. To this day, Dan believes I somehow screwed him over for not being able to deliver a high-pressure pneumatic system out of thin air.

One final note – I designed, ordered, implemented, and tested the entire electrical system on this vehicle. Both the large robot and small robot were controlled by a single remote controller, the entire electrical system (including 3 independent battery systems, 4 motor controllers, 2 receivers, 3 hobby servos and a variety of other components) was built on the last day of the competition in under 4 hours, and it all worked perfectly the first time. None of that is mentioned, of course.

WASTES OF TIME

2WD Dyno

See that device in the scene with the judges standing around the table? That’s a two wheel drive dynamometer. While I was picking up the RC car, Dan had Joel spend the better part of 3-4 hours building this contraption. I honestly don’t know why it was built in the first place – traditional dynamometers stress test a motor’s ability to produce torque, and give you information about how fast a motor (or car, in this case) can go. In our case, we had no way to change the torque setting of the dynamometer, we had no sensors on the dynamometer, and on top of all that, we had a four wheel drive car – which meant that the front wheels spun quickly when the back wheels were loaded by this device. At no point was it useful for anything. This challenge was fraught with this kind of pointless time-sink. Notable wastes of time included building the 2WD dynamometer for a 4WD car (3-4 hours), working on a high-pressure pneumatic system after I identified I couldn’t source parts (8-10 hours), purchasing, installing and testing the compound bow after being told it couldn’t work (8-10 hours), and a variety of smaller tasks after that.

At one point, Amy was responsible for designing and machining parts for a screw system that would be used to draw the latex bands back for firing the javelin. It would replace the winch we had been using, and would save us a few pounds (in exchange for 6-8 hours of labor). At the start of the last day, Amy identified that she couldn’t make the parts fast enough to complete the device. Dan instructed her to work on the device anyway, ‘because what else would you do for the last 6 hours of the build’? (It’s worth noting that at this point in time, the electrical system didn’t even exist yet.) It took the entire rest of the team stating in no uncertain terms that we needed to install the winch instead and move on with the design for Dan to back down, and even so he remained unhappy about it.

ME AND AMY

This episode didn’t show the camaraderie that Amy and I developed over the course of this challenge, which might make later episodes more confusing. We both worked to our full capacity, learning to work together in both design and manufacturing, and we developed significant respect each others’ skills.

PERFORMANCE

As expected, we completely annihilated the dash event. We beat Usain Bolt’s record-setting pace by 2.5 seconds. In terms of power-to-weight, there are few vehicles on this earth that beat a remote control car in a short straightaway. Then, it was time for the javelin toss.

Javelin Firing

This was one of the biggest shames of this show. There’s no reason that we shouldn’t have been able to design a latex spring slingshot launcher that shot a javelin 300 feet, especially one that was drawn back by a 2,000 pound capacity winch. In the end, we suffered from a failure of not having sufficient strength in a hobby servomotor to pull back on a common, off-the-shelf release mechanism. If we had tested at full load, we likely would have identified that failure mode and fixed it. We would also be able to see that we didn’t have enough latex bands on the launcher to hit the distance required. As it was, we never tested at full javelin pull because we simply didn’t have the time, and as a result were blindsided by that failure in the competition. And then, of course, there was the “jumping car”.

Real Jumping Car

I’m not sure there’s anything I can say about that.

POST MORTEM

In hindsight, the choice of an RC car base (even one as large as the 1/5th scale car we found) severely limited our design choices by forcing us to build small – the act of designing small, robust assemblies is incredibly difficult, and building parts for those small assemblies is even harder. It would’ve certainly been possible to create a much more robust javelin launcher that weighed about the same as our final system, but even so, it would’ve been hit and miss to attempt to hit the target distance of 300 feet repeatedly (because remember, the challenge was to come as close to 300 feet as possible – not go as far as possible). As far as the jumping car is concerned – if we had spent three or four days designing that system well, we should have been able to come up with something competitive. We only had to launch 5-10 pounds, compared to their 60 pound mini-car. It would have been a difficult design process to get right, as it involved a lot of balancing and coming up with a robust rail solution, but it would’ve been possible. Had we spent our time very well, I would have given us much better odds (let’s say, 50/50) of beating Blue Team. As it was, we stood no chance.

My hat is off to the Blue Team in this episode. They had fantastic team dynamics, and those dynamics resulted in a great robot. They planned their strategy well, and dominated the events they chose to focus on. The pneumatic piston they chose to use featured a standard, low-pressure system (though it was heavily modified), which meant they had access to parts from standard industrial suppliers. Deploying that system meant that their “mini-car” weighed 20 pounds more than our entire robot.