Sumo Bots C

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harryk
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Re: Sumo Bots C

Post by harryk » December 14th, 2010, 6:49 am

satchellwk wrote:Well, The robot is actually has one netbook laptop inside of it that acts as the control panel of sorts and is controled via bluetooth by another laptop. I really don't know how we could control the laptop inside the robot without using another computer.
Here's the basic concept of our robot, but with a different structure

http://liliputing.com/2008/12/building- ... robot.html
Looks good the only problem I see from that is that the netbook's battery will take a chunk of the voltage limit
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Re: Sumo Bots C

Post by maggymay » December 14th, 2010, 7:03 am

harryk wrote:
satchellwk wrote:Well, The robot is actually has one netbook laptop inside of it that acts as the control panel of sorts and is controled via bluetooth by another laptop. I really don't know how we could control the laptop inside the robot without using another computer.
Here's the basic concept of our robot, but with a different structure

http://liliputing.com/2008/12/building- ... robot.html
Looks good the only problem I see from that is that the netbook's battery will take a chunk of the voltage limit
Good point, I'd forgotten about that. If most of the allowed voltage gets taken up by the laptop battery then where is the power coming from to run the actual Bot...

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Re: Sumo Bots C

Post by Primate » December 14th, 2010, 12:54 pm

satchellwk wrote:Well, The robot is actually has one netbook laptop inside of it that acts as the control panel of sorts and is controled via bluetooth by another laptop. I really don't know how we could control the laptop inside the robot without using another computer.
Here's the basic concept of our robot, but with a different structure

http://liliputing.com/2008/12/building- ... robot.html
Hmm, that's actually a really interesting idea. I don't know exactly how heavy the netbook you're using is, but it looks like a lot of them are about a kilogram, which is a significant chunk of weight. That example bot you posted interfaces with an Arduino--why not just eliminate the laptop entirely and replace it with a WiShield or that Bluetooth Arduino I linked to before? You'd also solve your voltage problem.

I suppose if you're using Bluetooth, you could also use a cell phone to control it, but that raises the same issues as a laptop. Plus you really don't want to be controlling a sumo with a touch screen or something. That would be a disaster.

Edit: Actually, imagine how neat it would be if you harnessed the accelerometer of an iPhone to control your robot. Labyrinth on steriods, anyone?
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Re: Sumo Bots C

Post by sj » December 14th, 2010, 2:55 pm

Are we allowed to connect two 12v batteries in parallel? Also what kinds of batteries are people using? Where are good places to buy batteries?

Thanks :D
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Re: Sumo Bots C

Post by Primate » December 14th, 2010, 3:22 pm

sj wrote:Are we allowed to connect two 12v batteries in parallel? Also what kinds of batteries are people using? Where are good places to buy batteries?

Thanks :D
The combined voltage of all batteries in the bot has to be less than 14.4, so no. You could connect two 7.2v batteries in parallel (your standard six-cell NiMH/NiCd would do nicely), although that would get pretty heavy.
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Re: Sumo Bots C

Post by sj » December 14th, 2010, 4:06 pm

Where can i get 7.2v packs with high discharge rates but low mass? Sorry for the newbie questions but i am new to the world of battery packs.
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Re: Sumo Bots C

Post by Primate » December 14th, 2010, 4:29 pm

sj wrote:Where can i get 7.2v packs with high discharge rates but low mass? Sorry for the newbie questions but i am new to the world of battery packs.
Do you need all 14.4v? Otherwise, I'd highly recommend one of these. 1800mAh should be plenty to last you throughout the entirety of competition, and you really won't miss the extra voltage if you design your bot correctly. The RobotMarketplace also has a bunch of 11.1v lithium polymers with fewer amp-hours, if price is a concern.

You've gotta be careful with them, though. They have an excellent power-to-weight ratio, but they also explode and start fires if you overcharge them. (Serious impact can cause damage too, but we're talking dropping them off buildings, not sumo bot collisions.) Make sure you get a charger specifically for 3-cell LiPo batteries. (This is a good deal--$70 for a charger and an even better battery than I linked to above.)
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Re: Sumo Bots C

Post by Primate » December 14th, 2010, 4:31 pm

sj wrote:Where can i get 7.2v packs with high discharge rates but low mass? Sorry for the newbie questions but i am new to the world of battery packs.
Do you need all 14.4v? Otherwise, I'd highly recommend one of these. 1800mAh should be plenty to last you throughout the entirety of competition, and you really won't miss the extra voltage if you design your bot correctly. You can also pull 36A with that battery, and most motors will be well below that. The RobotMarketplace also has a bunch of 11.1v lithium polymers with fewer amp-hours, if price is a concern.

You've gotta be careful with them, though. They have an excellent power-to-weight ratio, but they also explode and start fires if you overcharge them. (Serious impact can cause damage too, but we're talking dropping them off buildings, not sumo bot collisions.) Make sure you get a charger specifically for 3-cell LiPo batteries (this one's not bad).
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Re: Sumo Bots C

Post by ichaelm » December 14th, 2010, 4:36 pm

sj wrote:Where can i get 7.2v packs with high discharge rates but low mass? Sorry for the newbie questions but i am new to the world of battery packs.
That depends on what exactly you mean by "high discharge rate," "low mass," and your price range. In general, though, I like all-battery and robot marketplace, as Primate said. If you want the best discharge rates under 2 kg, you'll want lithium polymer batteries.

Aren't you the same person who suggested using two motors with stall currents of 148 Amps each? I hope you're not still pursuing that idea. If you're trying to find batteries to accommodate 296 Amps, forget about it. Even if you do manage to find some (and pay through the nose for them), you really don't need that much power at all. Your wheels will just skid.

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Re: Sumo Bots C

Post by sj » December 14th, 2010, 5:10 pm

Yeah i dropped that idea too. instead i settled for a nice 540 motor with a good ratio.

Also how exactly do Li-Po batteries work? (what is the procedure for charging).
2011 Nationals Results : Sumo Bots 2nd, Helicopters 4rd, Mission Possible 4th, Towers, 9th
WWP SOUTH 3rd At NATS!!!!!

2012 Events: Robot Arm, Towers, Gravity Vehicle

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