Tech => Progress Reports => Topic started by: satacoy on January 29, 2018, 11:36:54 am

Title: Team Cosmos
Post by: satacoy 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:

More to come...

Pete - Team Cosmos
Title: Re: Team Cosmos
Post by: zacodonnell on January 29, 2018, 10:20:36 pm
Looking forward to it, since I'm too lame for Facebook :)

Title: Re: Team Cosmos
Post by: rcjunky on January 30, 2018, 11:42:28 am
Too lame or too smart :P I actually prefer reading here as it's everyone (well, that's optimistic) in one spot instead of a million team pages, but posting to Facebook is so much more convenient :P I need to start posting here too
Title: Motorama 2018
Post by: satacoy 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. (

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

Title: Re: Team Cosmos
Post by: Koolaid64 on February 01, 2018, 11:59:57 pm
looks like the speed controllers are getting better at handling a little thrashing. There are a couple of match-ups that will certainly be interesting for you.

I look forward to seeing it at the event
Title: Re: Team Cosmos
Post by: zacodonnell on February 05, 2018, 09:03:14 pm
This is gonna be great! I have brought a shell spinner to Motorama I think every year since 2004. There's some sweet irony in the fact that 2004 was the last year Killabyte competed there, and that I am unable to bring Triggo this year. It's like the essence of the shell spinner is passing back and forth :). I'll definitely be rooting for it to put on a good show.

Can't wait to hang out with everybody

Title: Re: Team Cosmos
Post by: zacodonnell on February 06, 2018, 09:53:27 pm
Also this brings back memories of the first ever robot video I saw online.  It took a whole night for me to download a 20 second clip of hazard hitting a shopping cart. Thanks for the flashback.

Title: Weapon Assembly Discussion
Post by: satacoy 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. (

Pete - Team Cosmos
Title: Re: Team Cosmos
Post by: zacodonnell on February 13, 2018, 09:36:01 pm
I really enjoyed that!

I think the pin sandwich should work well. When I made Scurrie I found there actually was a lot of force driving the blade off the end of the shaft, so the little bit of meat you have above the nub is a concern. When the blade hits a wedge it tries to torque it pretty hard and that can really push down on your pin. It's even worse when you are upside down and it hits a wedge and the whole blade wants to rip off the shaft with no floor to help convince it otherwise.  I've never built an ant so I can't say whether that will be enough material.

I noticed that your pins aren't a press fit in the shaft, and they appear to be solid instead of some kind of roll pin. That should make them easier to put in and out. I hate dealing with roll pins :)  I feel your pain on tapping the steel. The holes in the top of the shell on Triggo were all tapped 6-32 screws, 24 in all. I used four taps to do it because I was afraid of breaking one. It was annealed 4130 but it still sucked.

This is gonna be fun

Title: Weapon assembly
Post by: satacoy 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.
Title: Moto was Awesome
Post by: satacoy 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
Title: Angry Accountant
Post by: satacoy 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.

Title: 60s Failures
Post by: satacoy 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
Title: Re: Team Cosmos
Post by: zacodonnell on September 27, 2020, 08:05:28 pm
I just saw your video on Grond from AVC:

I very much enjoyed it. That kind of telemetry, tuning, and sensor work is exactly the kind of thing I'd love to have time to do with a version of my sportsman someday. Description videos that talk about the work and why you did it, where it might go from here, etc. are super interesting to me. I find myself with limited access to a shop at the moment, but videos like this and the gyro-walker bot posted here have got me excited about building again, even though the events are mostly drying up from COVID.

The reason I ran into the build report / video link at all was that I was doing some MOI calculations and my current computer setup doesn't have any form of 3D CAD so I was falling back to the old standby of the Cosmos calc. Thanks again for offering it!

Title: Re: Team Cosmos
Post by: satacoy on September 28, 2020, 12:14:49 am
Hey Zac!  Glad to hear you liked the video.  Like many projects, Grond had promise, and I'd love to revisit it someday.  The number of 12 pounds events with steel floors aren't many, especially now that AVC dried up.  Having that event local gave me hope to try a lot of interesting things like that.  I'll have to make it out to a WAR event eventually, but I've been saying that for over 10 years now...

Also glad to know that the old Kinetic Energy calculator is still getting some use.  It seems like a lifetime ago I cracked open the old Machinist Handbook to write the original version.  IIRC, I was at my parents house for Christmas, and there wasn't much going on.  I think I wrote that first version in Notepad, and it was the first time I'd ever used Javascript.  Crazy.

With the event schedule drying up, I've been spending more time on the electronics side of the house lately, not necessarily robot-related.  I'm still looking for that killer app on the robotics side.

I never posted about this project much, it's yet another I'd like to revisit:

This bot had mecanum wheels, LIDAR vision, and some additional sensors that let me do all sorts of things.  It could track the opponent, lock on to them, and then maintain a constant distance.  The stick on the transmitter would then either increase or decrease the distance from the opponent, and the "X" direction would circle around the opponent.  Sort of like old Zelda games.

Once I got it all built, I got tired of all the software challenges.  I believe I had 6 microcontrollers on there for various tasks, it was a little out of control.  Plus I realized that mecanum wheels are not very suited to combat.  But it was fun to lock onto a willing neighborhood kid, and watch them run away in panic, all the time the bot trying to maintain distance, and therefore "chasing" them.  The panic aspect was hilarious.

Title: Re: Team Cosmos
Post by: zacodonnell on September 29, 2020, 06:08:03 pm
These kinds of projects are so cool. Your sensor description and trying to come up with a way for it to fit into a fighting robot reminded me of one of the earliest build reports I read after making my own robot:

People have been doing neat stuff in this space for a long time. I think the sportsman class opens the door up a little more for this kind of thing, even something like meccanum wheels, because you don't have to face the giant spinners. I look forward to more people taking advantage of the opportunity to branch out into this space more. I like the spinners as much or more than the next person, but for a totally different reason. All-out destruction is fun, exciting, and showy, but also expensive, time consuming, and short-lived. Sportsman bots with custom control systems, sensors, and interesting weapons are cool for the engineer part of my brain rather than the entertainer part. I bet you could find a use for some of these techniques and concepts in there.

I'm especially interested in the setup you have for monitoring and telemetry. I've done some basic Arduino serial writing to debug the systems on Magneato, but I never took it as far as you did with a real time output graph, interactive commands, etc.  I always seem to run out of time to do that kind of tuning (just like you) but have never been ambitious enough to aim that high yet.  The 3d printed enclosures around the components are a nice touch. It makes it way easier to leave the wire/connectors on there and pull it out of a tool box to use as an actual tool. I'd love to add telemetry, status, and performance logging stuff to my machines at some point. Even just the graphs that come from the Castle ESCs can be fascinating when tied to the video for a fight.
Title: Re: Team Cosmos
Post by: satacoy on September 30, 2020, 12:00:51 pm
It is fun to read those old build reports. It's amazing how far some technology has come, and how some of those early ideas still haven't been fully realized.

I don't know if you remember our Sportsman from 2007 bot that used IR sensors to fire the hammer.  We had all sorts of fun with software simulators, then using the telemetry from the microcontroller to help us optimize our hammer speed ramp for quickest possible fire.  Unfortunately the hammer was too heavy, and it was less than impressive in real life.  Very Chomp-ish in a lot of ways.

Maybe it's time to get back into the sportsman at Moto.  I still enjoy the kinetic bots too, and really want to get my latest 12 pounder working a bit more, uh, functionally.