Author Topic: What kinds of wheel has best traction and why magnet can increase traction?  (Read 1207 times)

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Offline TaoBaiBaiTopic starter

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I m building a sumo robot  using  foam wheels,I feel the traction is not enough and I saw some articles say magnet can do it.As i know the arena is make of aluminium and magnet cannot pull it.Can anyone explain?

Offline Gertlex

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It's useless for us to try to guess what this article says and means when we could just read the article... if you shared it with us.  Context matters. :)
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Offline Soeren

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Hi,

I m building a sumo robot  using  foam wheels,I feel the traction is not enough and I saw some articles say magnet can do it.
Magnets are banned from most sumo competitions as well as sticky wheels and the way they usually test for sticky wheels (putting the 'bot on a piece of paper and lifting it - if it sticks you're out) unfortunately rules out stuff like what "Nano-pads" are made off, so it's a compromise...


As i know the arena is make of aluminium and magnet cannot pull it.Can anyone explain?
Not sure what you talk about, but a powerfull magnet generates eddy currents when pulled over an aluminum (or copper) plate, generating friction, but I don't believe that the speeds involved will generate any drag of importance.

Try dumping a neodymium magnet down a slightly wider copper tube for a real eye opener :)
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline dunz

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Magnets are allowed in some competitions, mainly the ones using the japanese and since last year the international ruleset. You can use neodynium magnets for increased traction, but you have to be careful, those magnets are really strong. If they're not fastened correctly they might get stuck to the dohyo.


Offline Soeren

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Hi,

[...] You can use neodynium magnets for increased traction, but you have to be careful, those magnets are really strong. If they're not fastened correctly they might get stuck to the dohyo.
Seems likeyou overlooked the...
[...] As i know the arena is make of aluminium and magnet cannot pull it.

Besides, with fixed mounting of magnets and a steel floor, magnets will probably be more of a nuisance to the user, that will have the increased drag for the full time, compared to the opponent, that only needs extra power for pushing it when it actually does.

All else equal, the better you spend your power budget, the better chance you have.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline TaoBaiBaiTopic starter

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Hi,

My power is quite good enough and the wheel can spin on the arena very fast when the robot has been blocked.I  just wander if there's any chance to improve the traction or friction of my wheel,I m using foam wheel and the traction is not so good.

Thnaks

Offline Soeren

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Hi,

[...] I  just wander if there's any chance to improve the traction or friction of my wheel,I m using foam wheel and the traction is not so good.
There's a couple of  fairly easy ways:
Add weight to the 'bot.
Soften the wheels prior to a match (experiment with different solvents, some use hand sanitizer - beware of aggressive solvents and test on a small spot on the side of a wheel).
Add a thin layer of RTV silicone over the outer perimeter of the tires (clean extremely well first and perhaps test on some scrap - it needs to be a very even layer).

If the tires are old, a light sanding on fine emery paper (150 grid or higher) may help (spin the tire by the motor while holding it over the emery paper with just a very light pressure).
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Online jkerns

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Hi,

My power is quite good enough and the wheel can spin on the arena very fast when the robot has been blocked.I  just wander if there's any chance to improve the traction or friction of my wheel,I m using foam wheel and the traction is not so good.

Thnaks

Don't spin the wheels.

You can spin them some to heat them up (that may make traction better (but it may not)), but you get more traction from a wheel that is just on the edge of slipping than you get from one that is spinning.  Dragsters are a bit of an exception because they spin the wheels fast enough to cause them to expand which raises the car which results in more force on the ground - but in general wheel spin is bad for traction.
I get paid to play with robots - can't beat that with a stick.

http://www.ltu.edu/engineering/mechanical/bachelor-science-robotics-engineering.asp

Offline Gertlex

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jkerns makes a good point.  If you can implement the equivalent of anti-lock brakes like cars have, that would be a nice advantage, I'd imagine.
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