Today we’re going to take a peek inside the clever and dangerous Airwheel X3. We’ll show you how to disassemble the Airwheel, and also what’s inside an Airwheel. Enjoy!
For those who aren’t familiar, the Airwheel is kind of like a minimized Segway: A motorized, single-wheel, self-balancing transportation unit. It’s a single tire, hub motor, some control electronics, and a battery.
You stand on the foot platforms and the controller continuously solves the inverted pendulum problem. You lean forward, it rolls forward to prevent itself from tipping. You lean back, it rolls backwards. With a bit of skill and a little practice, you too can zip around on this uber-slick (but heavy as hell) transportation unit like that guy from the old comic BC.
But we’re all here to see what’s inside, so let’s get to it. Click any of the pics for a larger version. Here’s the victim.
The ABS shell is held together by 7 screws on each side. So yes, you must flip it over halfway to remove the OTHER 7 screws from the other side.
Yeesh, they sure got a good deal on screws! The first 5 are obvious, as they ring the periphery of the wheel. Note the scratches from entertaining crashes in many directions!
The next 2 are a bit less obvious, being tucked back into the handle. Yank these two and let’s continue
Next, 6 heavier machine screws on each side hold the ABS shell to the hub/foot stand assembly. Yup, that’s another 12. Like I said, they got a good deal on screws.
Next, pull the non-control side of the shell up and away from the hub to separate the two halves. They are mated by the (thin) charging and (thick) battery supply wires seen here. In our case, the plugs were also hot-glued. This is probably to keep them from rattling apart during use.
The non-control side of the shell contains the battery, initially hidden by an aluminum sheet.
Removing the 6 screws holding the plate (and breaking the warranty seals ooooohhh) allows us to take a peek at the battery. Now that’s a Li-Ion pack! 57V? Better lick the terminals to make sure it’s charged.
The control side of the shell is tethered to the hub motor via it’s power cable. Be careful not to yank it too hard.
Again, removing the aluminum plate allows us to see the control side of the Airwheel.
Beautiful. A teensy little board can crank out 500W of physics-solving rage with 6 mosfets, a micro and a gyroscope chip. It’s a great age to be alive.
A closer look at the board reveals that the micro and the gyro chip numbers have been milled off in an incredibly clean manner. Neat!
But even this advanced obfuscation method falls to the good ‘ol head grease trick. Swab your sweaty brow with a finger, and quickly wipe across the milled surface: The shine will be removed from all the raised portions, leaving a pretty good contrast in the etched divots of the original part number. A sideways flashlight and some careful angling will usually reveal what was once missing.
In this case, it looks like an ST ARM Cortex M3 micro and an Invensense gyro. A couple of what may be op-amps are the only other two chips on the board. Super minimal, but they did a great job on the control loop – it feels and responds beautifully to the interesting problem of how to keep a fat dumb human upright.
We hope to look a bit more in to this fun little device in the future. There’s a pesky speed limit which really must be removed, and a couple other possible hacks that are in the idea hopper. So if anyone wants to collaborate on hacking this bugger, drop us a line using the contact page, and we can swap all those tasty secrets that aren’t yet suitable for public release.