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Topic: Challenge: horizontally / inertially stabilize a pizza on motorcycle (Read 3 times) previous topic - next topic

MaJiG


jabbado


Quote
What you want to do is make it so the direction of the total force on the pizza is orthogonal to it's plane.

Which is more or less what happens if the pizza box were rigidly attached to the motorcycle
frame, such that it's horizontal when the m/c is straight up and down, rather than being
"actively stabilized".



Exactly. I was hoping the OP would realize that. In fact his idea would work better for a car which doesn't significantly lean into a corner, which is the opposite to what he's thinking. I wonder if any university has ever obtained government funding to research "Topping Drift on a Pizza En Route"

Dnos

I'm too lazy to quote people directly but just a few things, and let me just say that I do like the input. I'm gonna take a couple wild guesses here:

1. There's no way for a topping to fly off of a pizza. Just going on the observation that cheese isn't actually goo and crusts arent actually glued to the box. When a pizza box is tilted too far, the pizza slides and crumples in a corner. The toppings don't just all pop off.

2. No pizza has ever been decimated by a car ride in the history of car rides OR pizzas. The pizza-en-route-via-car scenario is the ideal pizza delivery situation we're attempting to recreate on a motorcycle. Also because a horizontally stable platform on a motorcycle is awesome and could be  used for a number of things. Large camera rigs, carrying potted plants, etc.

3. The net force is not orthogonal to the lean angle of a motorcycle. In theory, yes. In practice there's a rider on the bike and that rider is never leaning at the same angle as the bike, so while a motorcycle does lean to overcome centrifugal force, you can lean off the bike for the same effect. Or if it's a tight, slow corner, you can just lean the bike and sit upright, as is what we're expecting to happen most-often. Plus I'm guessing it's the constant adjusting of lean angles that throws the pizza around.

4. I don't know if an arduino is necessary. I only know that it can be done using an arduino... and an accelerometer, a gyroscope, a motor, motorcontrollers, c++, kalman filter, and some other stuff I don't know about yet.... But if a handful of people can post videos of their two wheeled robots, segways, gyrocopters, and gyrocameras, all using the same tech, I think that this project can be done.

Shpaget


We're trying to prevent a pizza from crumpling into the side of a box when the bike is tilted at up to a 45 deg angle.

2. We're also trying to make a horizon-locked platform on a bike because it's awesome and if we try, we can.

3. The net force is not orthogonal to the lean angle of a motorcycle. In theory, yes. In practice the rider is never leaning at the same angle as the bike.


Lateral forces (the ones you want to reduce) will be greater if you keep the pizza parallel to the horizon than in case where the pizza follows the leaning of the motorcycle.
You do not want to keep the pizza horizontal, unless the bike is stationary or cruising (but in that case there is no leaning).
I'd keep the roll axis fixed, but compensate for pitch, because it is breaking that produces uncompensated acceleration.

Dnos

I wouldn't lock either axis if it can be avoided, but braking and throttle are definitely a lot easier to modulate by the rider than keeping the bike perfectly angled. The biggest thing I think will be the shorter, stiffer suspension on the bike, ie potholes, speedbumps, dips, etc. I havent thought of a good way to allow movement in 3 axis, apart from just suspending the thing on springs. For now I'll just worry about roll.

I'm much more of a motorcyclist than I am a physicist. This project to me seems like a great way for me to learn. If someone can help me figure out all the parts I need so we can get this whole thing built, we can test out everything in reality instead of just talking about it on the forums. I'm excited to work with arduinos and everything else.

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