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 Brushless Melty stage 1 Works!!

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rdubard
rjw
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rjw
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PostSubject: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeFri Jul 23, 2010 4:47 am

For the few that might be interested....I just did a test run with my 'Now working' brushless melty !!!

Translation, so far is nothing short of Spectacular Smile

Spinning Tortoise, now has to undergo a fairly hefty overhaul (in that placement of items has totally changed, but I am extremely impressed with this so far.

Some details: It is now running true pwm control, except that rather than running at 50Hz, it is currently running at over 300Hz!

I had to radically modify the code, but it's actually a bit simpler.

Giving credit where credit is due, the logic/meat is still totally Rich Oslon's.

Getting ahead of myself for a moment, I think that regular tank style drive can also be implemented without much problem.

More later... I NEED to shoot some video

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rdubard
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeFri Jul 23, 2010 3:50 pm

Yes, yes you do need to shoot some video. . . . (assuming this rain stops soon!)

I'm trying to follow what's going on, and I just want to check:
The controller used to send 50 pulses per second? And now it sends 300?
At 50Hz, the motors got one signal per bot revolution, so now they get 6?

If this is correct, then did you ever try running it with only one pulse per revolution (which I thought would be a problem)?

How did you bump the refresh rate so much?

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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeFri Jul 23, 2010 4:55 pm

The controller only sent On or Off based on timng, etc.

A commercial esc BB, Scorpion, brushed or brushless sends what is called pwm. pulses are between 1ms (low throttle ) and 2ms (high throttle). Also pulses are only sent every 20ms, which is 50 Hz.

Well, I never liked how the motors were being pulsed on/off. It draws an enormous amount of current and the brushless escs didn't like it either...

So I re-wrpte the code to ouput true pwm....now the 2 motors runf just like a brushless setup on our weapons., but it sends it at 6x the speed.

At this point, I could spin a bot at 9k rpm and pulse both motors on/off/on once per rev.

Honestly Bob, it's a totally different bot...I sounds quiet and it seems to move Really quickly.

the bot is totally out of balance, in that I removed 1/2 pound during the conversion. There is an event Saturday in Tampa..and i am thinking going. so the bot is in piees as I tyr to remove the velcro, tape, Bungee cords ,etc that I had everything tied together with for the initial test.

I might not go...not sure yet...but if it isn;t at least decently put together in time, I'd rather stay home and do some more R & D at a slower pace.

This is phase 1...I have a lot more that I can easily upgrade and improve upon..

Exciting... bounce affraid ..Expect to see a 15 and possibly a 120 from MLEC this year


Last edited by rjw on Sat Jul 24, 2010 4:17 am; edited 1 time in total
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Cody
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeFri Jul 23, 2010 5:33 pm

im sure you'll be letting them figure all of this out Razz
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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeFri Jul 23, 2010 7:45 pm

When you see this thing run and move, you are going to totally fall out of your chair... affraid

A lot of people have put time and effort into this...No question, brushed melty is a dog...it needed the push...

get ready to trade in your wedge...maybe... Razz

I will share this, and it is pretty CHeap !!!
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Jeff L
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeFri Jul 23, 2010 7:48 pm

Sounds interesting - I may just have to push to see if we can add a hobbyweight to the RoboJackets fleet this year.
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Dan Curhan
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeFri Jul 23, 2010 8:53 pm

I would really like to see this tomorrow!
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Cody
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSat Jul 24, 2010 12:28 am

$350 cheap?! lol
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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSat Jul 24, 2010 3:57 am

Dan Curhan wrote:
I would really like to see this tomorrow!

Not happening..bot is not quite ready to rumble... Sad
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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSat Jul 24, 2010 3:58 am

Cody Harris wrote:
$350 cheap?! lol

Most likely...NOT

I haven't mastered the art of a 'CHEAP build'...but I am working on it
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rdubard
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSat Jul 24, 2010 1:56 pm

Very exciting. I was pretty much convinced that having only one pulse per rotation was just too crude--seems like 6 per rev works nicely.

One of the aspects I'm still unclear on is how the 50Hz setup compared to the 'standard' signals the ESCs work on. Do most ESCs work with 300 pwm signals per second, or is this something new? Also, you seem to suggest that the new setup is actually proportional, rather than full on-full off, which sounds good, but makes me wonder how the code had to be altered to calculate the exact speed required.

I guess I really need to take a look at the sites you started with. Very Happy
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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSat Jul 24, 2010 7:43 pm

Very exciting. I was pretty much convinced that having only one pulse per rotation was just too crude--seems like 6 per rev works nicely.

When I say 1 pulse per rev, I mean 1 on/off pulse which timed properly, gets the bot to move and not just sit and spin.

One of the aspects I'm still unclear on is how the 50Hz setup compared to the 'standard' signals the ESCs work on. Do most ESCs work with 300 pwm signals per second, or is this something new? Also, you seem to suggest that the new setup is actually proportional, rather than full on-full off, which sounds good, but makes me wonder how the code had to be altered to calculate the exact speed required.

Standard for Rc trasnmitter. receiver is 50 Hz which means 1 pulse per 20ms. the reason for this is that lets say you have 7 channels. Each chaneel has to receive a pulse or 1 to 2 ms. and they all have to be constanly updated. To do this, the receiver sends info to the throttle, then the elevator, then the ailerons...etc. How it does this is by offestting the phase for each channel. For example, if all 7 channels are high (wot) then it would take at least 2ms x 7 = 14ms , not counting any delay in between switching to the next channel.

So in the 20ms window, the receiver can update all the servos or channels. All rc escs and servos have to be able to receive info every 20ms, but some can receive at a much faste rate.

The old brushed setup did allow you to change speeds, but that NO escs were used at all with the brushed motors, it could only do it by turning the motors completely ON or completely Off

Actually this is how all speed controllers work anyways, but true speed controllers normally do it smoother. Do a wki search for esc or pwm


I guess I really need to take a look at the sites you started with.

If you want /need to educate yourself then YES. If you see and like what I've done, then let's talk
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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSun Jul 25, 2010 9:08 am

Ok...not a perfect test platform and floor conditions have deteriorated, but here is the sneak preview..

https://www.youtube.com/user/ReadytoRumbleCombat#p/u

It looks to me like the typical melty wobble is all but gone??

over 9 minutes runtime on 2S Lipo...calibration mode speed is 1400 rpm, current top speed of 3500 rpm and it still translates at speed!

Let me know what you think
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Koolaid64
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSun Jul 25, 2010 2:21 pm

well ive wanted to build a melty sense that code was released, i dont have the time right now but when i do you can expect to be hearing from me because you can bet im going to go brushless Wink
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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSun Jul 25, 2010 7:14 pm

Kyle...

You're one of the good guys,,,I'll be there for ya brother... cheers

give this a bit of time, and actual speed of translation should be drastically improved

btw: still on Colsons.... Laughing
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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSun Jul 25, 2010 9:46 pm

Side note to self...

I find it a bit puzzling that the video has well over 100 views and yet only Kyle has commented??? both here and on the other forum Rolling Eyes

Feedback, good or bad is always welcome
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Cody
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSun Jul 25, 2010 10:01 pm

mom mom hey mom look, look what i did mom Razz

haha its is really cool! major accomplishment id say
I really wish i understood more about this technology, ive tried for two years now to get alex to build a brushed, they had the money to do it

How does it do starting up against the wall, and how is the progress on getting it to switch to normal drive?
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rdubard
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSun Jul 25, 2010 10:35 pm

I think most folks are intimidated by the tech of it, and so they aren't sure just how to comment.

If you want criticism, here it is--I cannot tell where the 'front' of the robot is from the LED flashes--they seem to sort of orbit around the thing. It's obvious you have control, but I can't see how you know which way it's gonna go. Maybe what I'm seeing is a result of the videocam missing pulses?

Also, thanks for the clarification on the signal pulse frequency--I had sort of figured something like that (in fact, I hooked up an oscilliscope to the signals from a BR6000 a few years ago, using the rising edge of ELE for sweep triggering and looking at each one of the other signals 'in turn,' so once you started your explanation, I got it right away) I suppose the existence of 2 channel, 3 channel, etc. transmitter/reciever setups makes the ESCs able to handle more frequent signals. Hmmm, with a 2ms max pulse width, I guess the limit is just less than 500Hz? If so, 300Hz seems like a safe, yet useful frequency to go for. . . am I on the right track?

To really understand how this functions, what I need to look into next is how the gyro/accelerometer works.

I actually don't want to you explain it all to me--I think I would enjoy figuring it out myself!!
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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSun Jul 25, 2010 10:43 pm

Cody Harris wrote:
mom mom hey mom look, look what i did mom Razz

haha its is really cool! major accomplishment id say
I really wish i understood more about this technology, ive tried for two years now to get alex to build a brushed, they had the money to do it

How does it do starting up against the wall, and how is the progress on getting it to switch to normal drive?

The oblong shape really helps it get out of corners....unless of course you're pinned.

I have options that would work for regular drive mode, but looking for something cleaner...cheaper, etc.
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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSun Jul 25, 2010 10:51 pm

rdubard wrote:
I think most folks are intimidated by the tech of it, and so they aren't sure just how to comment.

If you want criticism, here it is--I cannot tell where the 'front' of the robot is from the LED flashes--they seem to sort of orbit around the thing. It's obvious you have control, but I can't see how you know which way it's gonna go. Maybe what I'm seeing is a result of the videocam missing pulses?

Also, thanks for the clarification on the signal pulse frequency--I had sort of figured something like that (in fact, I hooked up an oscilliscope to the signals from a BR6000 a few years ago, using the rising edge of ELE for sweep triggering and looking at each one of the other signals 'in turn,' so once you started your explanation, I got it right away) I suppose the existence of 2 channel, 3 channel, etc. transmitter/reciever setups makes the ESCs able to handle more frequent signals. Hmmm, with a 2ms max pulse width, I guess the limit is just less than 500Hz? If so, 300Hz seems like a safe, yet useful frequency to go for. . . am I on the right track?

To really understand how this functions, what I need to look into next is how the gyro/accelerometer works.

I actually don't want to you explain it all to me--I think I would enjoy figuring it out myself!!

Video is missing pulses. Also, I rotated it in anticipation of tweaking inveted op, without having to add another led, so it doesn;t show tha well.

You have to see this at night....really cool

I will be writing a curriculum based on my findings with all of this, once the smoke clears...

You're getting on target with the whole pwm thing, but one nice thing about this is that while the transmiitter/erceiver might be only working at 50Hz, the brains is only looking at it from the point of view of..'Oh, so you wan to do this now?' No one can change speeds or direction in small fractions of a second, so in between input from the sticks, the mcu is beating the escs into submission.
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rjw
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PostSubject: Re: Brushless Melty stage 1 Works!!   Brushless Melty stage 1 Works!! I_icon_minitimeSat Jul 31, 2010 1:35 pm

Check this 20 second video out

https://www.youtube.com/watch?v=U9daI308sHE

Super translating at 3500 rpm !!!
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