How Hoverboards Work
Self-balancing scooter, two-wheeled board, Segway, hoverboard . . . They go by many names, but these self-balancing scooters are enigmatic pieces of technology. Arthur C. Clarke famously said that any sufficiently advanced technology was indistinguishable from magic. Hoverboards do seem like magic to many people, but while they certainly are high-tech gadgets, the basic principles of how they work aren’t difficult to understand.
Have you ever tried balancing a broom on one hand by its handle? Keeping the center of gravity for such a tall object centered and balanced requires constant adjustments. Now try running forward and coming to a stop while trying to keep that same broom balanced, and you’ll have an idea of what a self-balancing vehicle has to put up with.
You Spin Me Right Round
In order for you to successfully pull off the broom-balancing trick you need two things. First you need to have a way to sense where the center of gravity is shifting, and then you need a way to compensate for that shifting.
The sensor pads on a hoverboard are like sensitive scales that can detect minute shifts in your weight. The motors that drive the wheels then apply the correct amount of counter-torque to keep you balanced.
In order to keep the center of gravity where it needs to be in order to keep you upright, the hoverboard needs a reference point that’s level relative to the pull of gravity.
This is where the true modern marvel of the electronic gyroscope and accelerometer comes into play.
You’ve probably seen a traditional mechanical gyroscope before. It’s a series of concentric rotating metal rings with a spinning rotor in the center. Once the rotor is spinning in a given plane you can rotate the thing the gyroscope is attached to any way you want and always know where your original orientation was.
Thanks to modern micro-electronics a tiny silicon gyroscope can now be integrated into the microchip that runs your phone, or indeed your hoverboard. In fact, there may be more than one MEMS (micro electromechanical semiconductor) gyroscope inside your hoverboard.
In addition to the gyroscope, the system chip also contains several accelerometers.
An accelerometer is simply a device that measure the direction and strength of lateral movement. In other words, movement along a straight line. While a gyroscope can tell you which way you’ve rotated, it can’t detect acceleration in any direction.
Usually a set of three accelerometers inside the chip will measure movement in six directions along the X, Y and Z axes.
When you combine the information from the gyroscope and accelerometers, you have enough data to figure out exactly how the device is moving.
These micro-electromechanical devices are true wonders of modern computer technology, but the real secret sauce come from the software that takes that information and translates it into motor signals that allow us to zoom along on our hoverboards like they were magic carpets.
It’s that programming secret sauce that separates the good products from the bad ones.
Most of the components that make up a hoverboard are actually just off the shelf in this day and age. What’s not so easy to do is replicate someone else’s control software without actually pirating it.
This is one of the main reasons some cheap hoverboards are overly twitchy or start to behave weirdly under certain circumstances. The creators didn’t have the resources to test the software thoroughly or they simply didn’t know what they were doing in the first place.
The actual hardware can contribute to this as well. All MEMS gyroscopes and accelerometers are not made equal. Cheap ones can give inaccurate info or just be too slow for real time applications.
Pay No Attention to The Man behind the Door
While self-balancing scooters are engineering marvels, the technology and methods they use to work are actually quite mature. More than a decade of smartphone hardware development now makes the necessary components relatively inexpensive.
Still, for the average person even the cheapest hoverboard represents a significant outlay. After all, it is still stuffed with high-tech components and many hours of software design and testing.
It may be early days yet for the personal self-balancing transport, but thanks to technology whose time has come and a modern world looking for alternate mobility solutions, I have no doubt that products like self-balancing scooters will become ever more commonplace.