Interview: Former Mythbuster Jamie Hyneman's moonwalking electric shoes

You probably know him best as the straight-faced, beret-topped half of the Mythbusters duo, but Jamie Hyneman has been very busy since the show ended last year. Leading a team of engineers and designers, he's now concocted a prototype that sounds like something you'd see in an ACME catalog: electric shoes. Ahead of the launch of a crowdfunding campaign for the project, New Atlas spoke to Hyneman about how and why you'd mechanize shoes, and just what you might use them for.

The electric shoes, also known as Vortrex, look a little like roller skates, with wheels under the heels and something akin to tank treads under the toes. But it's what you can't see that makes all the difference: these sensor-laden shoes are stuffed with motors, batteries, gear reduction systems, speed controls, processors, Bluetooth connectivity, accelerometers, inertial measurement units (IMUs), and infrared for obstacle detection – among other things.

So what would you do with all that tech underfoot? The original idea (and ultimate end-goal) was to create a pair of shoes that acted like the moving walkways you use in airports, increasing your walking speed with no extra effort on your part.

"They're not intended to be 'ridden' – they're intended to be walked in," Hyneman tells New Atlas. "Instead of vehicles that you ride on, these are amplifiers. So you can set the gain of the amplifier, according to your environment or what you're doing. They're like having airport walkways strapped to your feet. So you just walk naturally, but you happen to be going more quickly. Like, if you walk at 3 miles an hour (4.8 km/h), these things would be rolling at 4 mph (6.4 km/h) so you'd actually be traveling at 7 mph (11.3 km/h)."

And that's once the motors have been toned down: they'd be a tad too fast if left untweaked.

"I've got 900-watt motors that are the size of a walnut – electric bicycles in the States they have a maximum of 750 watts or you have to get a motorcycle license with them," Hyneman explains. "And those will carry you at 20 mph (32 km/h) plus. When we started to play with that, the gear reductions and things that you have to have to bring it down to those lower speeds start to add weight."

Over the years the team has created six prototypes of the Vortrex, and an Indiegogo campaign has just been launched to fund the seventh – and hopefully final – version. But instead of going straight for the huge hurdle of making a pair of electric shoes that can traverse streets and rocks and grass, Hyneman and co have opted to start with a more controlled environment: the living room. Specifically, as part of a virtual reality system.

This is not a drill

Vortrex has its roots in a 30-year-old personal project of Hyneman's, when he first bolted cordless drill motors to rollerblades. If that sounds like something out of the Wile E. Coyote school of design, well… you're not far wrong.

"That actually worked surprisingly easily," Hyneman says. "I had a little right angle drive going right into the rear wheel of the rollerblades, and that's one of the times that I first realized the difficulty of doing that is you're this top-heavy weight, and if you goose the accelerator just the slightest bit too much, you fall down. And we can't have that."

As more serious development on the electric shoes kicked off from about 2011, plenty of other challenges revealed themselves. As it turns out, building such high-tech footwear is no easy feat (pun intended).

"What I discovered is the actual physical difficulty of building something that weighs only a pound or two that is able to have a lunging 200-lb (90-kg) load on top of it, have its own power source in it, and be flexible like normal shoes are and no larger than normal shoes are, give or take," says Hyneman. "It's fairly straightforward to put some wheels or rollers or treads on a shoe-shaped object. The devil's in the details, as far as getting where we want. It can't be like walking in a pair of rollerblades or something."

"Some of our prototypes I had tried first wanting them to flex like a normal shoe, and not feel like you have a brick on your foot," he continues. "So I put a hinge point at the ball of the foot, but the fact that you still have to carry the power through that hinge point, as well as if you do have a power transmission of whatever sort, and a motor attached to it, things like belts and gears need to be held in a precise relationship to each other, or you'll skip teeth and things like that. So trying to get something that flexes as fully as a normal shoe does is no small feat."

Balancing act

It might seem intuitive to give the wearer full control over their speed, but as Hyneman says, that's how faceplants happen. Instead, the shoes have been equipped to take care of everything themselves, so all the user has to do is set their desired speed and the Vortrex will slowly work up to that, and no faster. Infrared sensors, meanwhile, can interfere and slow them back down if the road gets rocky.

Skating requires a certain level of coordination, sure, but from test runs in the workshop, Hyneman says the oscillating motion of walking makes the Vortrex more stable than other motorized personal vehicles, like Segways and electric skateboards, where the rider is standing still.

"If you stand in surfboard or skateboard stance, or facing fore-and-aft like those so-called hoverboards, if the thing takes off too quickly you're going to fall on your ass, if it stops too quickly you're doing a faceplant," says Hyneman. "I found that just like it is when you're skating on ice, with this kind of oscillation from side to side, your body kind of naturally balances. It naturally is already in flux, and is compensating for the movement of the weight. So it's a much more natural thing than just staying put."

But of course, not moving is just as important as moving, and as anyone who's ever tried to stand completely still in a pair of rollerblades can attest, sometimes that's the hardest part. To keep the wheels and treads tightly locked when you're stationary, the Vortrex system uses a combination of gear reduction and specialty brakes.

"One of the largest parts of the engineering effort that I personally have done on this is looking at highly efficient but non-back driving gear reductions for the motor," Hyneman explains. "We've also experimented on ultra-compact brakes to control that, so if they start to go out of phase with your motion and they're going to slip out from under you, the brakes would kick in. Either the power of the motor or the power of the brake will control that, to where your foot is locked to the ground just like it would be in a shoe."

At the moment, the shoes communicate and coordinate with each other via Bluetooth, but further down the track that connection could be used to tap into the suite of sensors you probably already carry everywhere: your smartphone.

"We can and probably will make use of the accelerometer in your phone, as a way of feeding in to tell what your body is doing," says Hyneman. "We've done studies on the movement on your body and looking at telltale signs in key places that are unique to what happens when you're about to faceplant. We can have a relatively limited number of sensors and potentially even down to just using the phone to be able to anticipate your movements, and do things essentially like the Segway does, when it keeps you from falling off. It has self-balancing capabilities, and we'll be using something not unlike that on this thing. These phones are just small supercomputers, so we can detect things from subtle cues, a series of micro-movements that will give the phone a clue as to what's happening with the body and anticipate it. It's pretty neat stuff."

Compared to the goofy-looking Segway or not-hovering hoverboards, Vortrex are downright modest in the looks department. And that's by design: Hyneman and the team want the shoes to be basically invisible, so you wouldn't necessarily be able to tell if you passed someone in the street wearing them – at least, until they casually stroll past you at 7 mph.

"That was one of the things that I noticed when I first started dreaming up this concept, was that you look like a dork when you're on those things," says Hyneman. "My insistence on making these things very light and flexible and everything, is that it's supposed to be invisible. You don't want to have something that you've got to lug around, like you can't take the Segway on the bus or on the subway, or put it in your car. You can do that with electric skateboards, but you still have a thing that you've got to lug around, it's not invisible at all."

Virtual practice run

In theory, the electric shoes sound like a great last-mile transport system, but that's a bit ambitious for now. While the team plans to get there eventually, they decided to run with a more controlled testbed first: virtual reality. And in the process, the shoes might casually solve an inherent design problem there too.

Room-scale VR systems like the HTC Vive and Oculus Rift are great at tracking a player's head and hands, but the feet go neglected. To get around that mobility issue, games often either confine players to small virtual spaces or let them teleport through larger environments, and while those are fine stop-gap solutions, neither are particularly immersive.

In the Vortrex's VR mode, the treads actually roll backwards with each step you take forwards. That means that you can walk naturally and the shoes will "moonwalk" you, keeping you firmly in the middle of the play space. It sounds like a particularly elegant alternative to devices like the Omni treadmill, which is immersive but a tad too bulky for the average living room.

"There's been a lot of attempts at dealing with that," Hyneman explains. "There's these elaborate treadmill designs, or you get into this frame that restrains you, and you've got a dish-like floor in it that's slippery. But we feel we can do that electronically with these things, without needing to be restrained. You can imagine how much this is going to complete that VR experience. Rather than just standing there, or sitting at a desk in front of your computer, you're physically involved with it."

Beyond entertainment, the moonwalking mechanism of the indoor version of Vortrex could be used as treadmills for exercise as well. But the two aren't mutually exclusive: Hyneman says combining fitness and video games is a great way to trick yourself into working out.

"I put my laptop on top of my treadmill, and I would get in-sync with what they were doing (on-screen) and I found that there was something intriguingly immersive," Hyneman recounts. "When you're on a treadmill and you've been doing it for a while you're getting tired, you start to be distracted by the exertion. But I had found that the combination of also having to do fine motor-control targeting with the game took your mind away from the effort. Which meant that I would set foot on the treadmill and start playing the game, and just kind of snap out of it an hour or an hour and a half later. It was effortless, basically, it just pulled me entirely away from the dreariness of having to plod away and exert myself."

Campaign trail

The team has just launched an Indiegogo campaign to fund the continued development of the electric shoes, starting with the VR version. If that bears fruit, the next steps will be to work on an indoor iteration of the walking-speed boosters, targeting warehouse workers and those in other large facilities, before attempting to tackle the great outdoors.

"I've done some other designs that I think may get us there, but given that we're pushing the limits of physical reality with what we're trying to do here, that's why we're crowdsourcing it to get funds to bring some heavy FEA (finite element analysis) skills to the forefront and do a proper job of engineering it," says Hyneman. "I'm good at making quick prototypes to prove a concept, but if this thing is going to reach its potential, we've got to spend some money on it. So that's kind of the point that we're at. But we have done enough to see that yes, you can do this."

Honestly, the campaign has a bit of an unfinished air about it, but that's kind of in character here, especially with such an ambitious and on-going project. That said, the team has been very upfront about the chance that the electric shoes might never see the light of day, so instead of offering the shoes themselves as a reward, backers will receive swag hand-picked by Jamie. These Hyneman Survival Kits are packed with tools and items like space blankets, duct tape, flashlights, water filter straws, multitools and hatchets, in a durable aluminum case.

"The Survival Kits we're hoping will be something that is appealing of themselves," says Hyneman. "This is something that I thought of as sort of like a 'Go Kit': if something bad happens, what are you going to grab? There's a little zipper bag that you can put a couple of grand in, so you got your money, you've got a flask that you can put some whiskey in, because you're going to need a stiff drink. A first aid kit, and something that you can get fresh water with. I've got stuff like that all over the place, but I don't have a thing that's in a nice aluminum case, ready when the next earthquake comes and I've got no power or water."

The campaign will fund development of the seventh Vortrex prototype, and if it works, backers will be given first dibs to buy them. Price-wise, Jamie estimates that they might be "in the neighborhood of a premium electric skateboard," so a couple of grand or so. At the time of writing, the campaign had made about US$5,000 of its $50,000 goal, with a month remaining.

"It's an R&D project, we think we can pull this off based on what we've seen with the prototypes and everything, but it's seriously pushing some physical limits," Hyneman tells us. "We're cutting our teeth with the VR system, in a more controlled environment that makes this task a little easier, and that's why we're only putting that out there. We have a high level of confidence that we can pull that off and do it acceptably well. And whether we get to full airport walkway or not, I'm hoping that interest in the VR thing will allow us to fund further development and take it the whole way."

Campaign: Indiegogo