Aftermath fo Franklin

Well, I just got a bit of free time and started to look at the bots that fought at fFranklin

started with the beetle, in that it seemed to work ok right till the end

We did NOTHING to this bot, except change batteries and in the end swap out the receiver.

Turns out that 1 of the motors had come loose, so it was also only really working on 1 wheel drive. the other was still tight....I guess that if I wasn;t brain dead, I might have noticed...lol

More as I weed thru things

the ant had the same problem....I was told that it was only working on 1 wheel....just needed a belt adjustment....so far the beetle has a bit of ti damage from when it was immobile and both bots have dull knocker edges,,,,nothing too serious so far

next is onto the 12

On a side note, I think that I need some knockers with various tip shapes for use against different opponents.

I'm sure that the latest anti-melty thinking is to use a wedge against them....so I need to come up with some anti-wedge knockers also, some anti plastic knockers that can get a bite or dig into the plastic.

ST beat Mr. Croup by digging into the Ti wedge (knocker had a sharp edge at the time), but by the time it got to the finals, the knocker had no sharp corners and ST just bounced off the ti...in the last 2 finals, Mr. Croup had its way with ST for easy wins.

the R & D continues...

While implementing regular drive mode into the meltys is a long term goal, I think that in the short term, some changes will be made to help them perform a bit better.

I am thinking that calibration on the fly might be a good feature. rather than having to spin the bot down to switch bwtween regular and config modes...which might have helped in a few instances where calibration went south.

I also suspect that my current accelerometer is not up to the task especially in the biger bots....250g's rating is marginal at best...the forces are probably double that when the melty hits something....

Rich's whole setup was based on a bot spinning at maybe 1000 to 2000 rpm....

all my meltys spin in the 4 to 5k range or higher.

If you go to Rich's link on acceleromoter placement calcualtions and plug in the numbers, you'll see that at these speeds, even a 250AG unit needs to be very close to the center to not be overloaded.

Add to that the extra G's when a big 12 hits something and I believe the accelerometer goes into overload, even tho they are rated at 4k G's, that is probably a rating at which the unit will be destroyed.

Once you get to he point of having to mount the unit like 1/4" to 1/2: from center, several problems arise.

1) the sensitivity of the unit is zilch. I can ca;librate at 2k, but when Ispin 4k, it is off

2) the unit being around 1/4" square, where exactly is the point where tings happen internally. icalled analogue devices and sparkfun...NO ONE could/wouild answer this.

I knew that the current unit would be marginal, but as usual, I'm on the edge of things and need to find a more robust unit and with higher capacity...and will sacrifice resolution in the process.

Others use gyros in their setups.....might be another way to go, but it has taken al of my spare time just to get these to the point where they are now....

Be warned that you are not walking into a tried and proven deal when attempting melty...you will be part of the R & D...so give up and run now...or put up and help move it forward

Alex Udanis wrote:

Rich was sensible, your just crazy

I remember reading your has like a reach of like 18" or something close to that, but you mount the accelerometer in the middle?


I know when you first read this, it kinda defeats the purpose of a accelerometer, but it might help with impact. Have you ever considered shock mounting them?

3 things

1) again check the calculator....at 1" away from cl, you could probably only get 1000 or 2000 rpm out of it before overload.

2) my whole electronics board, etc is shock mounted.....the 12 spins a bit over 9" radius or 18" diameter. the oblong shape causes the illusion of the bot actually growing, or looking bigger than it is , once spinning.....I like that...it looks too cool....all my meltys look bigger when spinning


3) Yes I am crazy, but the difference in energy between 2k and 4k is ...well you figure it out

Did I ever mention that I was a cutting edge...R & D, tinker till it blows type of maniac?

on a side note, my 12 drumbot spins at 45k.....lol all show and no go

alex

Let us not lose track of the recent timeline

Several months ago, it was thought that brushless melty was impossible....All of the supposed people in the know told me to forget it, it could not be done.....look how far we've come and in such a short time.

If you jump on the melty bandwagon, you need to read everything again and again, in order to make smart choices.

Looks like there will be a demo of small bots on Staurday at the Belen event.

Paul Grata and friends will bring a small insect arena for demo purposes. But it looks like no kickplate, so my little meltys will run in the 8 x 8 arena.

On that note, I went thru the ant and beetle and now they are running like they never have in competition....looking good.

Next, I need to go thru Sting and if I have time, maybe the 12 melty.........

the melty 12 looks to have been inadvertently put so far out of calibration, that it refused to run for more than 5 to 10 second spurts. I re'flashed the mcu and at least on the bench, it is running.....the motor endcaps had worked loose (new this would happen but didn;t have time to brace them), but no damage was done.

So, the motors hnow have a somewhat unique motor brace, consisting of a pair of stepped round alu parts with a screw, nut and lockwasher assembly mounted between the endcaps. the assembly pushes the endcaps away from each other. it is so rigid, that the actula motor mounting screws are almost not needed. we'll see how this works out in the near future...perhaps this weekend at Belen, if anyone cares to dance with a 12 melty.

More to come....but so far not much wrong with any of the meltys....