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Messages - satacoy

Pages: [1] 2 3 ... 6
1
Progress Reports / Re: Team haciM
« on: March 02, 2018, 02:48:06 pm »
I always kick myself when I see these sorts of build reports, forcing me to realize how over-complicated my designs always turn out.  Keep up the good work!

Pete - Team Cosmos

2
Progress Reports / 60s Failures
« on: February 26, 2018, 04:29:28 pm »
60 Seconds of Glory ended with two wins, and two losses, similar to it's AVC performance.  The bot has a ways to go before it's really decently competitive, and failures continued to plague us at Moto '18.

For Motorama, we'd spent time improving securement and placement of the electronics.  Previously at AVC, we'd resorted to zip ties, straps, and electrical tape to keep things attached to the frame.  We added attachment points to the magnet housing to keep wires from moving too much, and reorganized our electronics to neatly fit in the one fully enclosed compartment in the frame.

We also zip-tied and taped all bullet connectors and xt60 connectors.  Our most common failure in previous fights and testing were connectors popping loose.  It's easy to underestimate the g-forces that the occur within a full body spinner.  Not only did we see disconnects during big hits, but if we started to coin or vibrate violently, things would either bust free or unplug themselves.

These changes seemed to be for the better, with no connectors popping free during the matches.

Our first loss came at the hands of Megatron.  Jamo was easily controlling us, and got a few big chops in.  Our weapon stopped working after a few hits, and we tapped out.  The drive was still fine, but the VESC controlling the weapon was flashing out the dreaded "DRVR" error.  At first we thought that we'd fallen victim to the VESC gremlins that you hear about, even though we were only running at 8s and very low eRPM.  Our hope had been that we wouldn't see driver chip failures due to not pushing the limits of the VESC.

Luckily (I guess), upon further investigation, it looks like one of Jamo's hits had physically popped a FET off of the VESC board.  We've had a history of bad solder joints on the DIYSkateboard sourced VESCs, and this looks like it's possibly another case of a bad joint. 

With not enough time to reconfigure our backup VESC to fit in the electronics bay, we reverted to strapping the VESC to the frame.  We used a lot more tape, and had more options for zip ties, and this variation won a fight.

Our last fight was against Boom Boom, a multibot by the wacky guys at Bots FC.  The fight was going well, until one of our drive sides stopped working.  The other side stopped responding shortly afterward.  We were able to use shell vibration to briefly show translational movement, but that too died, giving Bots FC the win.

Our first side seems to have split one of the MarkForged printed pulleys.  We were cutting it close in terms of how much meat was left between the key way and pulley, and this finally caught up to us.  There was also some interesting deformation on the teeth of another pulley, and we had keyways that seemed deformed by heat.

With only one side functioning, it appears we asked too much of the 50 amp Spider ESC on the other side, which eventually burst a few FETs.

The second VESC died a violent death.  One of the retaining zip ties had popped off, which gave the VESC enough wiggle room to physically pull a motor lead off of the board, solder pad and all.  Once that happened, several other components smoked on the board.

Another interesting thing we learned this competition was how oversized our batteries are.  Originally we though we were cutting it close with 2200 mAh on the weapon battery, and 1300 mAh on drive.  We never used more than 300 for the weapon, and 200 for drive.  The plan is pick up smaller batteries that can still source appropriate current, and use the weight savings for bigger ESCs, and better mounting options.

In terms of the pulley failure, we'll at the very least add .05" to the width, which should make them a tiny bit stronger.  We may also look at swapping to aluminum pulleys, if weight allows.  I'd rather stick with printed if possible, due to the easy of customizing them, and the weight savings.  We'll do a full tear down and see if any of the other pulleys show any hints of failure.

<Pictures to follow once I'm by a real computer>

Pete - Team Cosmos

3
Progress Reports / Angry Accountant
« on: February 19, 2018, 11:31:55 pm »
Angry ended up going 5-2, with a tough initial loss to Physique Black as the first fight.  While an exciting match to watch, it mostly consisted of Ian's bot throwing me around violently.  Angry's always been a resilient bot, and held up well for quite a while, until the new steel 3/8" axle bent.  I suspect that I was inverted, and Ian's drum smacked the end of the blade, given him a good lever to bend the shaft.  I tapped, swapped in a spare shaft, and was ready to go.

I had 4 wins in a row, including a great fight against Foiled!.  Fire Arrow finished Angry off with a cow-catcher type of attachment.  The second shaft ended up quite a bit tweaked too, but was still functioning by the end of the tournament.

7 fights did a number on Angry.  It's one thing to be more resilient than your opponent, but you also have to keep things running fight after fight.  Things were getting loose and janky by the Fire Arrow fight.  One of the 4 retaining screws on the weapon motor kept loosening up, eventually jamming up the weapon belt/pulley system. 

After the Physique fight, the weapon motor can actually started to separate from the axle.  The motor is small enough that this is just a press-fit, no set screws in sight.  I believe the motor cover was the only thing that kept the can from flying all the way off.

The drive system held up well, as did the electronics and frame.  The Foiled! fight caused a good portion of the blade to flake off at a known stress riser.  Next time I won't get fancy with the tooth design, and leave it blunt.



The new standoff that improved my blade height when inverted worked out well, although I only used it against non-spinner bots.  The small magnet at the top seemed to work.

In terms of upgrades, I'll see if I can find a source for harder precision shaft.  Or maybe I'll make one out of S7, and just temper it to a relatively malleable state.  I'll slightly tweak the blade, but will keep the pin-based solution, since it seemed to work fine.

Overall, I was more than happy with Angry's performance.

Pete

4
Progress Reports / Moto was Awesome
« on: February 19, 2018, 11:10:12 pm »
I enjoyed myself, as always, at Moto this year.  While I was there in 2017 as a spectator/judge, I'd forgotten how much fun it is to actually compete.

We had a good traveling group with myself, David Small, Luke Quintal, and Chad New.  The trip went fairly smoothly, although David missed his initial flight, and had to catch a ride from Philly with us.  My erratic driving, a few midnight wrong turns, and a few near misses in Amish country kept things interesting.

I tore down both Angry Accountant and 60 Seconds of Glory, and will follow up with details on how each performed, and where I'll be making changes.

Pete - Team Cosmos

5
Progress Reports / Weapon assembly
« on: February 14, 2018, 02:12:59 am »
It does intuitively feel like there's not enough meat on the bottom. We'll see what happens, and I can always fall back to the old setup.

6
Progress Reports / Weapon Assembly Discussion
« on: February 13, 2018, 09:16:31 pm »
Here's a bit of discussion on updates to Angry's weapon assembly.  Most an excuse to see if I can talk for a few minutes and not sound like an idiot.

https://youtu.be/rqN2-LJxgQY

Pete - Team Cosmos

7
Progress Reports / Motorama 2018
« on: February 01, 2018, 11:07:17 pm »
I'm bringing a slightly updated Angry Accountant to Motorama.  She last competed there 11 years ago, previously taking first in the ant class in 2005 and 2006.  While I don't think she'll place due to her aversion to wedges, she pulled off a surprising 2nd place recently at AVC in a field of 26. 

Chad (Wazio) and I are sharing driving duties on "60 Seconds of Glory", a re-imagining of the classic Killabyte from back in the day.  The original shell, gearbox, and a few bits and pieces are in the new bot, but a new frame and brushless drive/weapon system are in place.  It's no Triggo, but absolutely terrifying at speed.  Here's a bit of test video from last weekend.

https://youtu.be/CGxvqqqWHFc

We're hopeful for a few glorious fights, but again don't have high hopes due to the self destructive nature of the bot.  At AVC we were plagued by electrical disconnects and mounting issues due to running out of time and having to slap everything in place.  Things will be mounted better this time around, but at full speed, it's unlikely she will survive a big hit.  In fact, if we do well, we'll have to turn the bot over to someone else, as we're flying out Sunday evening, and have to drive back to Philly to make our flight relatively early.

We'll have a few more Colorado guys with us, both Luke Quin and Robert Cowan are showing up.  Robert did well with "Crippling Depression" at AVC, sailing to a first place finish in the 30s.  Luke will have an ant, but unfortunately will not be bringing RumHam which has done well at both AVC and RoboGames recently.

I'm looking forward to seeing a lot of familiar faces, smelling the weird smells of the venue, and probably partially freezing my butt off!

Pete - Team Cosmos


8
Progress Reports / Team Cosmos
« on: January 29, 2018, 11:36:54 am »
Figured I'd start a new topic here to highlight any interesting projects that may pop up.  I'll post primarily to Facebook, but I'll try to post the non-conversational, larger items here.  It's a heck of a lot easier to find things here.

For those who do Facebook, here's a link to the normal feed:  https://www.facebook.com/TeamCosmosBots/

More to come...

Pete - Team Cosmos

9
Progress Reports / Re: Twisted Sick Robotics
« on: January 13, 2018, 05:02:31 am »
Awesome, thanks!

I think the rest of our big items are very likely to be there, since they're so common.

Dremel
Clamps
Hammers
Hacksaw
Vise
Heat Gun

Pete - Team Cosmos

10
Progress Reports / Re: Twisted Sick Robotics
« on: January 10, 2018, 12:02:30 pm »
Great!  That was the item we were most concerned about.  Thanks!

Pete - Team Cosmos

11
Progress Reports / Re: Twisted Sick Robotics
« on: January 09, 2018, 06:50:38 pm »
Kyle (and Zac, if he's listening):

Rumors are that you typically bring a drill press to the event.  Will that be the case this year?  The Colorado guys are starting to plan on what tools to bring, and a drill press would be very helpful, yet difficult to bring with us.

Zac, the story is that you typically have an arbor press.  Same question, are you bringing it this year?

Thanks!

Pete - Team Cosmos

12
Progress Reports / Re: Team Cosmos - Angry Accountant - A New Beginning.
« on: October 30, 2017, 09:05:26 pm »
Hey David (I think I have the name right),

I would have to rely on that older post.  I haven't changed anything significant on Angry since this last build, and 3oz for the main frame sounds about right.  She may not hit super hard, but she has yet to break after 3 or 4 competitions.

It's a real challenge to get an all aluminum frame, dead shafts, and indirect drive on all motors into one pound.  When I started on this build, I intentionally went all aluminum just for the challenge.  I think you could make a similarly resilient bot more easily using a mixture of materials.  If I had to do it all again, I'm not sure I'd bite off the same challenge.  It was a lot of work and anguish.

Pete - Team Cosmos


13
I feel good knowing that I've eliminated one small reason to keep IE around!  :-)

Pete - Team Cosmos

14
I found some time to crack open the Machinery's Handbook to see if I can make sense of the units.  According to the handbook, there are three types of Moment of Inertia calculations typically used in engineering:  Moment of inertia of plane area, Polar moments of inertia of plane areas, and polar moments of inertia of masses.  I followed the equations for that third kind, which are specified to be used in equations involving rotational motion.

For this type of calculation, the units are described as thus:  "If units are in the foot-pound-second system, the units are ft-lbs-sec^2".  That does differ than the label that I give it on screen of "fp/s^2".  I abbreviated this "ft lb/sec^2" on the original version.  According to the above quote, this would properly be labeled as "ft-lb-sec^2", or something similar.  This is equivalent to slug-ft^2.

But, that doesn't agree with your findings of a timeless unit.  The other two types of MOI appear to have units of Inches cubed.

So, I'm not sure what the right answer is.  I'll update the page to reflect ft-lb-sec^2, since that matches more closely my source material.

Pete - Team Cosmos

15
Progress Reports / Re: Team Cosmos - Angry Accountant - A New Beginning.
« on: February 28, 2017, 09:56:29 am »
My phrasing was bad as well, I realize you're only talking about the unit label I'm using.  And my memory isn't that good, I remember talking to you in '07, but I don't remember fighting Scurry.

I couldn't find the old Delphi thread on the calculator.  I'm not sure if it was in the SubLight forum, the Battlebots forum, the RFL forum, etc.  I remember Eric Scott being pissy about the calculator, but then he was pissy about most things. :-)  I did get a kick while searching the forums on seeing old names and topics pop up.

Once I'm back in Boulder I'll dig out the handbook and see if I can understand why I used that label.  I bet you're right about it being off, I just want to look at the source one more time to see if I had a good reason.  I think I wrote that original calculator in like a day, didn't know javascript or the math behind KE, but just ran with it and it seemed to work.  The original version would only work on IE, if I remember correctly.

Pete - Team Cosmos

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