Article: Lit Motors C-1 – Will It Stand Up?
California start-ups are renowned for challenging perceived wisdom, sometimes with exceptional success and other times with expensive failure. It’s hard to guess which outcome Lit Motors might be heading for, because it’s product isn’t like any other car for sale. It’s an electric car with just two wheels. Or an electric bike with a lot of bodywork. Or both.
The C-1’s big innovation is that it can balance on just two wheels at a standstill without falling over, and without the driver needing to stretch out a toe to touch the floor. That means it can be fully enclosed, making it safe and snug, while remaining almost as lithe as a motorcycle.
We’ve seen self-balancing, two-wheeled electric transport before, of course, in the shape of the infamous Segway. But the C-1 is different.
The Segway has its pair of wheels set side by side, which means it needs to balance in the same direction as it travels to and fro. That’s relatively easy, or at least it is for a quick-thinking computer equipped with some tilt sensors and a drive motor. It’s like balancing a broom upright on the palm of your hand. As the broom tilts and starts to fall, you shift your hand around to compensate and if you’re any good at balancing you’ll keep the broom’s centre of gravity directly above your palm. The Segway does broadly the same thing, moving its wheels quickly and often imperceptibly forward or backward just enough to keep itself upright.
Alas the C-1 can’t use the same trick. Its wheels are line astern, which means it tends to tip over in a direction where driving the wheels simply won’t help. Speed up the wheels as you’re falling over and you’ll only hit the deck travelling faster.
Instead, the C-1 uses gyroscopes to keep from falling over. The principle is familiar to anyone who’s ever seen a child’s spinning top, or spun a coin. As long as the spin lasts, staying upright is not an issue. The spin creates its own stability. The heavier the gyroscope, and the faster it spins, the more firmly it resists the tendency to topple.
In a machine more complicated than a spinning top, you can keep a heavy gyro spinning very fast for long periods of time, simply by attaching it to a drive motor.
That’s the basis of the C-1’s uncanny ability to stay perched on two wheels, but it does a bit more than simply sit and spin its two gyroscopes to stay balanced.
A gyroscope’s knack of staying upright is well known – what’s less commonly understood is that if you grasp a gyroscope and try to twist it – so that the spinning disc moves from turning horizontally to turning vertically, say – the gyro will exert a twisting force not simply against you but also at right angles, either pushing towards you or pulling away. The exact sense of this unexpected twist will depend on whether the gyro is spinning clockwise or anticlockwise.
The engineers at Lit Motors have used this phenomenon – it’s called precession – to their advantage. By mounting their two spinning gyros in a pair of hinged frames, they can automatically twist them to create a force, on demand, in the right direction to push their balancing vehicle upright the moment it starts to fall. That means the C-1 is not just stable, it’s actively balanced. Push on it from the side, and it pushes back.
It can push back quite hard, as it turns out. Lit Motors says the C-1’s gyros can exert up to 1,300lbft of torque if they have to, which is much more than enough to keep it upright in a strong sidewind. They say the C-1 will even keep its tyres firmly on the ground if it’s T-boned at a junction. It may slide sideways on its tyres, and it may wobble, but it shouldn’t fall down as long as the gyros aren’t damaged.
And because the forces generated by the gyros can be actively controlled, they aren’t a problem during those times when you actually want to tip over – when you’re barrelling along and want to lean into a curve. Instead, the onboard computers and sensors can stabilise the C-1 so that it negotiates bends smoothly and safely.
The C-1 concept is incredibly clever and unlocks a long-dreamt-of possibility – a vehicle that combines the weather protection and safety of a car with the agility and space efficiency of a motorbike.
Of course a great idea built on sound science does make a hit product. People have to like it. People have to trust it. And people have to buy it.
As Segway amply demonstrated, getting those three simple-sounding things right can be much harder than the toughest science and engineering.
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