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rjw



Joined: 04 Jul 2010
Posts: 110
Location: Miami, Fl. USA


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R2RCR USA

Hello everyone from the usa

I'm Richard from ready to rumble combat robots....

Just thought that I would drop in and try to share some interesting stuff with the rest of the world.

I recently figured out how to run brushless motors in melty bots. If anyone is interested in how to do this, just ask away....it's too much fun., not to share...

my Youtube channel is 'readytorumblecombat'.....have a look and let me know what you think.....

thanks...let's move this melty thing forward

btw: It took around a month to get my account here activated????

Post Fri Aug 27, 2010 2:24 pm 
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dyrodium
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Joined: 24 Aug 2004
Posts: 6476
Location: Sydney


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Hey mate, I'm a huge fan of your brushless melty's and am very keen to make one myself (just ordered the 250G accelerometer from sparkfun Very Happy ). Aaron in QLD has been our local melty pioneer and I wanna jump on the bandwagon. Laughing

BTW massive pain with the registering, I think Brett who manages the forum does it all manually to stop spam bots but maybe he's just too busy these days?
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Post Fri Aug 27, 2010 3:12 pm 
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Valen
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Joined: 07 Jul 2004
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Location: Sydney


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I was pondering your melty stuff looking at videos etc, I was thinking adding a gyro might help with the drift. Though a high frequency modulated IR beacon might help more.

Interested to hear your opinions on those additions.
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Post Fri Aug 27, 2010 5:37 pm 
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marto
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Joined: 08 Jul 2004
Posts: 5459
Location: Brisbane, QLD


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So as far as brushless in melty's is going are you using just standard RC ones with a micro pumping out PWM signals at up to 400Hz?

I was interested in actually hacking the ESC directly and using the back emf detection for odometry. Then you can remove the Accelerometer all together.

Steve
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Post Fri Aug 27, 2010 11:08 pm 
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rjw



Joined: 04 Jul 2010
Posts: 110
Location: Miami, Fl. USA


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quote:
Originally posted by dyrodium:
Hey mate, I'm a huge fan of your brushless melty's and am very keen to make one myself (just ordered the 250G accelerometer from sparkfun Very Happy ). Aaron in QLD has been our local melty pioneer and I wanna jump on the bandwagon. Laughing

BTW massive pain with the registering, I think Brett who manages the forum does it all manually to stop spam bots but maybe he's just too busy these days?


Aaron was one of the people that I had email contact with, when I first got into this and he is the reason why I tried to join this forum a while back. I wanted to let him know that brushless melty was a reality. He and a few others were very helpful from the onset.

When I noticed that he posted a link to 1 of my videos, I gave up trying to join, but then yesterday I received an email stating that my account was finally up and running...so here I am.

btw: the company that actually manufactures he Sparkfun accelerometer now has a 500 G unit, but it is very pricey...

Post Sat Aug 28, 2010 1:58 am 
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rjw



Joined: 04 Jul 2010
Posts: 110
Location: Miami, Fl. USA


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quote:
Originally posted by Valen:
I was pondering your melty stuff looking at videos etc, I was thinking adding a gyro might help with the drift. Though a high frequency modulated IR beacon might help more.

Interested to hear your opinions on those additions.


First off, while I might be the first to implement brushless melty, I have to give a lot of credit for this to the real pioneers. Rich Olson, Aaron, Perttu and some others have really paved the way for this to happen.

I simply picked up where they left off and ignored the 'It can't be done' comments..so here we are.

I am by no means an electronics or programming guru....just an ex computer overclocking hack (and a mechanical engineer).

Also, I am terrible at actually driving combat robots, which may account for much of the drift. So I can't really say with any authority, whether a gyro or anything else would help.

What i do know is that the robot needs to be built like a brick outhouse, and motor placement (if not on center), needs to be well thought out.

Also, unlike most other meltys, mine seem to translate better at higher rotational speeds. One of the keys to this is overhead. Motors/escs, etc. need to be able to spin the robot 10 to 20% faster than your theoretical top speed.

I've been shooting for around 5000 to 5500 rpm (top speed), but they can spin well over 6k. This allows for speeding up of the higher rpm motor during translation at top speed. Hope this makes sense.

Post Sat Aug 28, 2010 2:13 am 
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rjw



Joined: 04 Jul 2010
Posts: 110
Location: Miami, Fl. USA


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quote:
Originally posted by marto:
So as far as brushless in melty's is going are you using just standard RC ones with a micro pumping out PWM signals at up to 400Hz?

I was interested in actually hacking the ESC directly and using the back emf detection for odometry. Then you can remove the Accelerometer all together.

Steve


Perrtu pointed me to the multi rotor copter people, who have been hacking cheap bescs for quite a while. They need escs with no frills or smoothing as is founf in the car escs. Right out oif the box, with no modifications, they can accept pwm signals at around 400 Hz.

These include all of the Hobbywing heli escs. They are sold under numerous names, such as Turnigy plush, Exceed volcano, Hobbywing pentium and more.

I simply took Rich Olsons on/off code and converted it to pwm (currently at just over 300 Hz.)

The back emf idea sounds doable, as long as you have provisions in your code to calibrate things.

I simply do R & D for an educational combat robots (highschool) team here in Miami. We won the national BotsIQ event last year, taking 1st and 2nd in the 15 pound division, although national representation was somewhat limited. Our 40k rpm S7 drums were very effective.

This year, they will build a 15 and possibly a 120 pound melty....should be entertaining, to say the least.

I will be taking a 1, 3 and 12 pound melty to a competition in Philadelphia in October. Although it is on a wood floor, it is a non-ejection arena, so we should see how well they hold up, and if the competition can withstand the constant transfer of energy.

The cost of building a brushless melty can be fairly reasonable, and I hope to see some efforts materialize in your part of the world soon!!!

I'm here to share and help if I can

Post Sat Aug 28, 2010 2:23 am 
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Spockie-Tech
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Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia


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Re: R2RCR USA

quote:
Originally posted by rjw:
Hello everyone from the usa
I'm Richard from ready to rumble combat robots....
btw: It took around a month to get my account here activated????


Welcome Richard.. Sorry about the delay in activating your account.

As Angus (Dyrodium) mentioned, I have found it necessary to do manual activations on the new accounts, not so much to keep out Spam Bots (which are fairly easy to detect and block), but to keep out the human wares peddlers.

They typically are actual humans using free Gmail/Hotmail/Yahoo accounts, who pass all the bot-checks and then post adds for Idiot-Phones, Viagra and all the usual crap.

I got sick of cleaning up after them, so now before any account is activated, I manually review each one, web-search the email address they used to register, and If I find any other forums/wikis etc that have posts from the same email address posting ads for junk, I just delete rather than activate the account.

This takes a while, so I tend to let 5 or 10 new account registrations accumulate, then do them in a batch. Add to that I have been very busy the last few weeks, and it took a while for me to get to review the last batch of new registrations.

Of the 10-12 registrations in the last batch, about 5 of them were spammers, so while its a pain, its worth doing to keep the forum clear of crud.

I also figure, if anyone is serious about joining the forum and posting useful stuff, they wont mind waiting a week or two to get in.. So thats why.

Anyway, like I said, welcome and great opening posts..

Melty Brains are a rarely-explored area of combat bots, due to the level of micro knowledge needed, and so far, only Aaron has made a serious attempt at them, so its good to see someone else pushing the edges.
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Post Sat Aug 28, 2010 5:05 am 
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rjw



Joined: 04 Jul 2010
Posts: 110
Location: Miami, Fl. USA


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Thanks for the warm welcome!!

I didn't know what to think, outside of maybe people from this side of the pond might not be able to post.

Rich Olson made his brushed code available for all to try, and the actual circuit didn't seem that complex. I had some very bad luck with brushed motors along the way and almost gave up on the whole project.

Also, over here, meltys have a bad rep, in that many feel that they are 1 hit wonders. Both bots get destroyed and it's over, plus in many cases they don't move all that well.

I am hoping that some here, there and everywhere might give it another shot and let's see how far we can push this. It might just be 1 of the big contenders in the near future....only time will tell.

As per Aaron's sig, having the entireweight of a combat robot as the weapon, something's gotta give!!

Post Sat Aug 28, 2010 5:54 am 
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dyrodium
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Joined: 24 Aug 2004
Posts: 6476
Location: Sydney


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Normal spinners used to be 1 hit wonders so i'm sure it's only a matter of time.

Also, the beetle weight arena we have in development lacks dropouts, so a melty is not going to lose from 'death by rebound'. I'm also fairly interested in the whole tooth design, no body has really tried a shredderator style approach to a melty which might make it less likely to throw itself into the walls on every hit and still maintain an aggressive edge. Something worth persuing perhaps. Smile

Any tips on motors to suit a beetle melty? Hobbycity has many many. Laughing
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Post Sat Aug 28, 2010 12:36 pm 
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rjw



Joined: 04 Jul 2010
Posts: 110
Location: Miami, Fl. USA


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quote:
Originally posted by dyrodium:
Normal spinners used to be 1 hit wonders so i'm sure it's only a matter of time.

Also, the beetle weight arena we have in development lacks dropouts, so a melty is not going to lose from 'death by rebound'. I'm also fairly interested in the whole tooth design, no body has really tried a shredderator style approach to a melty which might make it less likely to throw itself into the walls on every hit and still maintain an aggressive edge. Something worth persuing perhaps. Smile

Any tips on motors to suit a beetle melty? Hobbycity has many many. Laughing


Not sure what your shrederator tooth looks like...any pics?

Also here, ants are 1 lbs and beatles are 3....how does that compare to your local rules?

I am using very small neu motors (razors), that I got in a clearance sale. They are absolutely amazing, extremely efficient and you can count on better than advertised kv even at full load.

What weight robot are you considering?

Here's picture of my 1 lbs melty tooth



Here's with the cover removed...

Post Sat Aug 28, 2010 1:04 pm 
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dyrodium
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Joined: 24 Aug 2004
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Location: Sydney


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Our rules are the same, just converted into metric, thus 3lb beetleweights are 1.36kg or so. I'm keen to make a beetleweight, as that's the active class at the moment in the NSW competition. By shredderator tooth design I meant lots of smaller, sharp teeth rather than one big ke 'knocker'. Possibly not as effective in a smaller robot but worth investigating.

I didn't realise you were actualy using two brushless motors... Nue motors are fantastic but way above budget... I will search around for some high KV motors of similar spec but perhaps less quality or price. Smile
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Post Sat Aug 28, 2010 6:00 pm 
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assassin



Joined: 27 Jun 2004
Posts: 1105
Location: SunshineCoast


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rjw thats a bitchin little bot you have there. What are the problems/issues with it, what do you NEED to improve?
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Post Sat Aug 28, 2010 6:12 pm 
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marto
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Joined: 08 Jul 2004
Posts: 5459
Location: Brisbane, QLD


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Ants are 150g which is a lot less than 1lb but other than that everything is the same.
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Post Sat Aug 28, 2010 8:32 pm 
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rjw



Joined: 04 Jul 2010
Posts: 110
Location: Miami, Fl. USA


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quote:
Originally posted by dyrodium:
Our rules are the same, just converted into metric, thus 3lb beetleweights are 1.36kg or so. I'm keen to make a beetleweight, as that's the active class at the moment in the NSW competition. By shredderator tooth design I meant lots of smaller, sharp teeth rather than one big ke 'knocker'. Possibly not as effective in a smaller robot but worth investigating.

I didn't realise you were actualy using two brushless motors... Nue motors are fantastic but way above budget... I will search around for some high KV motors of similar spec but perhaps less quality or price. Smile


Hobbycity or King has small outrunners in the 3200kv or better range for under $12 each. If I am allowed, I can dig them up and post the link.

I actually bought 22 razors for $25 each, some 300's,350's and a couple of 400's. When they arrived, 1 was missing, so they found and sent me 3 more. So far I have 2 in the 1lbs, 2 in the 3 and 2 more in Sting, which is a pretty stout 3 lbs drumbot which I recently converted to brushless drivetrain.

At less than $25 each, with shipping, I think that I stole them. If not for the shipping, I'd offer a few up for sale.

With all the R & D that went into our drumbots, which now all have single tooth solid S7 drums spinning at 30 to 40k, the single blunt tooth seems to have proven to be pretty effective and more durable than multiple small sharp teeth. (jmo)

We also like Colson wheels, which are used on all the meltys and all our drum and powered wedgebots as well. They just plain hold up.

Post Sun Aug 29, 2010 1:34 am 
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