Nosedive Video - Why would this happen?



  • @mrb Yes, but the pressure pads only know if something is pressing on them or not, they don't even measure how much pressure. You can move your center of mass anywhere you want and the board won't do anything until you actually tilt the deck.



  • @thegreck

    the pesky blue sensor strip is unnecessary in any case--but if the pressure pads aren't weighing the rider then what's their fumction?



  • @mrb They're both just on/off switches and their function is simply to detect whether or not there's a person standing on the board. You can find videos on the forum of people who had faulty sensors, and when the board tries to self-balance without the weight of a person on it, it's pretty ugly. Just a lot of bucking and wheel spinning.

    The original pre-Kickstarter prototype had an actual button you had to depress with your foot, but then they came up with the dual-sensor idea which is a smarter and less-conspicuous solution. And the fact that only one of the sensors needs to be depressed once your going over 0.05mph makes accidental motor disengagement less likely while riding.



  • @mrb said in Nosedive Video - Why would this happen?:

    @thegreck

    the pesky blue sensor strip is unnecessary in any case--but if the pressure pads aren't weighing the rider then what's their fumction?

    Also, the blue strip is just paint on the griptape, to show you where the sensors are located, which is under the griptape. I don't think any of it is unnecessary.



  • @thegreck agreed. IMO it would really be nice if they marked (maybe with a second color / inset box) the actual sensors, so you could be certain you're covering them. @MichaelW explained to us that each of the sensors is basically in the middle of each of the 2 blue square-ish shaped boxes. I can figure that out no problem, but when you're going 15mph it would be nice to be able to glance down and see if you're on or off one or both of the exact spots where the sensors are.



  • @thegreck Had a pretty good diagram of the sensors coverage.

    I tend to ride with my feet farther apart and front foot angled almost 45 degree.

    I was able to move the pads 1" out on each giving plenty of room.
    Closed the gap with gorilla tape.

    0_1473259074226_0823161146_resized2222.jpg



  • @thegreck

    this board has two wooden footpads. in one footpad under the blue paint there are two punkass switches known around here as sensors.

    i can't open my board because i'm always standing on it, but i think that under both footpads are pressure plates. these robust digital scales would weigh the user from both sides and this ratio would be the input used for both balancing and control input (gas/brakes).

    if there are two pressure plates then the sensors are unnecessary as the plates could handle rider presence more conveniently and reliably.

    is all physical input on the board collected solely by gyros?



  • @mrb Yes, it's all gyros and accelerometers. The technology behind the Onewheel is the same as those 2-wheeled hoverboards, which is the same as the Segway, which is the same as any self-balancing device. They all use inverted pendulum theory, which has been around since the 1970s at least. It's purely based on solving the angle of the upright by moving the base under it:
    https://www.youtube.com/watch?v=D3bblng-Kcc

    It's just like balancing a broomstick on the palm of your hand. You don't need to know how much the broomstick weighs, you just have to move your hand under it when it starts to fall over.



  • @thegreck

    thanks for your reply.

    the information from pressure plates would use the same human pendulum to balance the board and the physics of it would be the same. however, the computer would account for the distribution of weight aside from board pitch.

    i would guess that Onewheel uses the exact same reverse-engineered balancing code used by all the devices you mentioned, without steering logic and with values changed to match the hardware.

    i had an apparently wrong idea that all these devices weigh riders and reconcile this information with that from on-chip gyros.



  • @mrb They didn't have to reverse-engineer the other self-balancing devices and strip out the steering logic. The code for self-balancing has been around for decades, as have DIYs for making your own "Onewheel" (as far back as 7 years before the release of the Onewheel). All of the self-balancing devices just used this code and made changes based on the device they planned to use it on.

    At the end of that video I shared, he demonstrates putting containers of liquids of various sizes and weights on top of the inverted pendulum, and the unit has no problem keeping them balanced. Weight doesn't even come into play, only speed and angle. There's no reason to muddy up the works with adding scales under each footpad (just another thing to break) when all you need is a simple on/off switch just to let the board know someone is on it.


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