How does balance & handling actually work?
I'm curious what the OW actually measures to achieve balance and handling?
The ride seems very intuitive most of the time, but sometimes (like with pushback) it's counter intuitive.
For example, is acceleration/deceleration based on absolute board angle, change in board angle, weight distribution, or change in weight distribution?
Intuition says board angle, but I suspect it's more than that.
The board obviously knows it's angle well enough to give an error if it's turned on while vertical.
And what about lateral stability? Is it stable just because it's a big fat tire, or is there some assist happening too?
The app mentions that Classic & Extreme have different cornering characteristics. How is that achieved or is it just an artifact of different acceleration modes?
Just curious... knowing the details might open some interesting riding ideas :)
Found this remark from Julian in another post....
"The board is not controlled by the angle it's riding at with respect to ground but by where the center of mass of the rider is at with respect to the board itself."
I've been curious myself about how the board knows where the center of mass is. Segways use fluid level sensors (like electric probes that measure the angle of the surface of a tilting glass of water). It's probably the same thing here. A lot of self-balancing devices are hitting the market now - maybe Segway's patent recently ran out. Alternatively, the controller might infer center of mass through a combination of motor speed and changes in board angle from moment to moment, though that would require a fair amount of sensor sensitivity and fast cycle times at the processor to keep up without noticeable lag that might throw off the rider's balance because measuring angle changes vs a moment ago is by definition a lagging indicator. The only other way I can think of (given that there are not separate foot sensors on each side of the board with precise, variable weight measuring capability) would be some kind of fore/aft sensor inside the hub motor at the axle. That sounds expensive and complex. All that brings me back to the fluid level sensors of the Segway.
@OP: Lateral stability is just from the big wheel, yeah (an elegant, simple solution that also makes it easier to ride and to go off road) - there's no motorized tilt to the axle, and you may have noticed there's only one wheel so there's really no other way the manage lateral forces (damned physics).
I'd also like to understand it better.
From a physical reading I don't understand how the board can know exactly anything other that the tilt of the board compared to level besides the speed and if the sensor is activated. They may want to base board handling off center of mass, but that has to be a calculation based off of board tilt and speed from what I can think of. Of course their may be some electronics in play I don't know or understand besides the fact that I know very little about this stuff:)
I believe assuming the board knows anything more than the tilt angle and the current speed is over-thinking it. As for the counter-intuitive feel of pushback, it may be an unavoidable consequence of the way level is maintained. The rider leans forward to accelerate and the board obliges by speeding up. When near the limit, pushback is needed. How can the board do that ? Only by accelerating. Hence the counter-intuitiveness, we expect a slow down, but the board accelerates and the nose goes up. The rider now needs to lean back, to allow the board to slow down, but leaning back may feel difficult with the front foot being higher. My 2 cents.
Good points on the physics of the board. It seems there is nothing other than the ground and tire to push against or leverage. But, I imagine the forward momentum can also be "pushed against" with a more complicated mechanism. If also seems unlikely that's needed or useful.
I did notice the tire & hub seem to rotate around an unmoving axle. In theory (or perhaps just in my imagination), the axle could be rotated relative to the board independently of the tire to change board inclination. Again - seems unlikely, unnecessary, and perhaps useless or imaginary physics :)
Regarding pushback... I've been riding a lot further lately, so I ran the battery out at cruising speed a couple times without notice. I was surprised how natural the pushback felt in that situation. Perhaps I'm more in sync with the board now - because the first time I honestly wasn't sure if the board slowed itself down or if I did it myself.
Interesting comments regarding sensors. Fluid level sensors sound interesting.
There seems to be no discernible lag. Whatever they are doing, they are doing it well. Really getting addicted to riding this thing.
I don't recommend buying one of your self-employed and work at home. It's a bit like living at the bottom of a ski lift... Hard to resist the urge to go ride.
@Julian Feel free to give us your IP secrets =)