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#1
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Re: Omni Wheels Survey
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we should get all the robots that have omni wheels and make a big gallery of them, that would look cool.. ![]() |
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#2
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Re: Omni Wheels Survey
well it was our first year with omini wheels-- we actually have to fix them up-- only problem i saw was the rubber on the wheels-- a lot of driving just wore them down-- all well-- i'm sure S.P.A.M. won't mind sharign our design-- nobody we saw had a drive system like us-- and we plan on making them better
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#3
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Re: Omni Wheels Survey
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#4
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Re: Omni Wheels Survey
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#5
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Re: Omni Wheels Survey
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/-------\ |oooooo| |oooooo| |oooooo| \-------/ for some reason the spaces arent staying between the two walls of my robot so i put o's in the middle when that robot is moving "up" on the page, all the motors will be applying force in that direction. The one thing i can't seem to figure out is wether 100% of their force is in that direction or 1/sqrt2 of it is in that direction because the wheels are at 45deg angles to the direction we are measuring force in. Now basic physics would say that yeah, its 1/sqrt2 because the force is being applied at a 45deg angle, but the odd thing is, when you get out the other xy component vector, it doesnt seem to be applying a force when the robot drives straight assuming the omniwheels have no significant friction to lateral movement. Now im sure no one got that, but if you did, help me cause im really stumped by this. |
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#6
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Re: Omni Wheels Survey
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i'm pretty confident that that you're right with the second one ,[sqrt2]% of available motor power (but then again, i've been awake way too long). that is the reason i think the mecanum/ilon wheel setup is better, since it allows the motors to apply 100% of their power to full forward/back or left/right movement. |
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#7
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Re: Omni Wheels Survey
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Both systems get [(sqrt2)/2]% efficiency in the x and y directions. Mecanum wheels have the rollers at 45* angles which produces the same vectors as a normal holonomic platform with its wheels at 45* angles. |
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#8
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Re: Omni Wheels Survey
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#9
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Re: Omni Wheels
Team 931 used them for the first time this year. We wanted a robot design that was longer than it was wide, for stability with a long arm, and knew that our robot would not turn well with four standard wheels. There are two omnis on the front and two pneumatics on the back.
When we switched to the omnis, it turned too well. Think about it - omnis act as casters when the robot turns. The operator would push the stick to turn and the robot would turn, but it would keep turning when the operator moved the stick back to neutral! The polar moment of inertia kept us going. If you want to go with omnis, I recommend one of three things: -holonomic drive -exponential stick control for better turning sensitivity at low speeds -(best option in my mind) a gyro to counteract the overshoot I'm trying to get a white paper out on these wheels by midsummer. Brandon Heller Mentor Team 931 Alum Team 449 Quote:
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#10
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Re: Omni Wheels
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#11
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Re: Omni Wheels Survey
Omni wheels actually worked great for my team this year. But, we didnt have them on the ground the whole time. We had ours attatched to a pnumatic cylinder and when the stoke was out the wheels were down and when the stoke was in they were up. We saw early in the build season that the pnumatic wheels that were provided in the kit didn't allow for smooth turning. So our drive/chassie team came up with the idea of having a set of omni wheels stowed up under the robot and that could be deployed when ever the driver wanted them to. This turned out to be a great asset for out team this year because our driver could easliy maneuver the robot.
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