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Messages - Somebody

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1
No worries!  You definitely have given me a few more things to chew on.  There is no thermal or electrical model for the battery or ESC.  I need to decide how far to go with this before it isn’t fun.

The Maytech motors are so tiny!  Wow!

Exactly why we went that direction!

And yeah, that does seem like a lot of curves and efficiencies and thermal modeling and math. Maybe if current limiting ends up modeled in, it becomes hard top-end limits for many controllers? Nobody will be having fun with their robot burning out 90 seconds into a fight due to overheating anyhow. So instead there would just be a hard upper limit. Like "Trampa VESC Mk3, Provides 60A up to 14S" or whatever the actual specs are. So then you end up just having a slow robot if you under-gear (like HUGE 2019).

2
Hmm.  I hadn’t thought to put a controllable current limiter into the game.  That would probably be helpful.  We don’t do it with our own ESCs, and I didn’t realize it was a thing that people do for brushed ESCs.

Right now brushed ESCs are completely unlimited.  I ended up artificially reducing the torque for drive motors to dull the initial current (and torque) spike.  Drive motors were so torquey initially that the simulation couldn’t keep up and it was causing the lighter robots to jump unrealistically around the arena.

It wouldn’t be difficult to add a current limiter to ESCs.  60-100 amps is low!  I haven’t built a drive system with the A28-400s yet, but I suspect most robots will exceed that unless they are geared down a lot.

It sounds like the brushless motor model might be reasonably close to real life.  I limited current to some suitably small value.  I can’t remember the exact number, but it is something like 25% of what the stall torque would be for a brushed motor.  You might try the brushless motors in game.  They have an insane top speed but their current limiting means they have to be geared way down.  If we can find the numbers for the motors you are using I would be happy to put them in the game for testing purposes.

We began to swear by current limiting when we were one of very few teams who could keep 48V Ampflow motors alive without them burning up. Their stall current was 700A or something crazy so just the instantaneous spikes were enough to detonate them. Ours ate themselves later due to high-speed issues, but even then the current-limiting prevented any fire on what likely would have otherwise been a short-circuited situation. Twice. The Ragebridge2 controllers we used had it as well as the Kelly controllers, and the VESC6 brushless controllers that we'll be using for 2020 also have current limiting. At this point I see it as a requirement to make a reliable robot.

As for the 60-100A, that was due to compounding faults. The first was under-gearing the drive, which was an intentional choice to save weight. The main issue was that when calculating weapon spinup, we didn't calculate the effects of motor efficiency. Since the Ampflow motors were outputting 30% of their inputted energy as heat, they were swallowing 30% more battery power during a fight than we expected. So we had to re-wire the robot from 2 batteries for drive/2 batteries for weapon to 1 battery for drive/3 batteries for weapon. We did this after the Jasper fight. This meant that 60A was the max current we could run to guarantee that our drive batteries wouldn't die. After fighting Gigabyte and Bronco for three minutes each, we felt comfortable enough with our in-fight battery usage to bump it up to 80A for HyperShock and 100A for Whiplash, if my memory serves correctly. I agree it was super low, and it's why we've done a lot of work to swap away from those parts for 2020. But the rules don't say you have to be fast, you've just got to move!

Here's a link to the motors we're using this year:

https://maytech.cn/products/brushless-hall-sensor-motor-mto8085-160-ha-c

I think limiting the torque of brushless motors, especially on startup, is the right move. The real answer to brushless motor torque is probably some kind of curve that you would need to dyno-test motors to develop, and even then is dependent on ESC choice, ESC settings, the gearing style in the robot, and probably a hundred more things that we don't even know yet. It's telling that even the teams don't truly know how they will perform until it's tested in the robot. Otherwise, sorry to add another wrinkle of complication to your simulation efforts. You're doing awesome work!

3
That's awesome! And I think the A28-150G's should work perfect in that size. A few heavyweights even boldly use them. Valkyrie has always just been 2 A28-150 motors, although it's never been tasked with pushing much. Since we used the A28-400G's, we were using the same gearboxes as well, which held up fine for 6 fights at BattleBots and 3 at Robot Ruckus (in thwackbot mode). We won't be using them for 2020 (or 2021... or 2022.......), as we designed in Maytech 8085 Brushless motors. We were swapping the weapon to those motors and decided to change the drive over as well, so that all of the spares can be double-useful.

Nice!  I%u2019m excited to see how you feel about the brushless motors vs the AmpFlows.  I felt like I was designing the brushless motor simulation in a vacuum.  We don%u2019t use them in real life, and manufactures data is nonexistent.  In the end I assumed that torque is limited by current over most of the RPM range.  It makes the brushless motors in the game behave like constant torque devices.

1. We are putting the A28-400s in the game for the next build.   Would you be willing to build a mock-up of a certain robot in the game to see how it drives?  We have Colossus, but I was hoping to build simulations at several different weight classes to see how close we can match the real life robots.

2. Would you mind sharing the ESCs you are using in your brushless setup?  Are there any other components we are missing?

0. So I was told by someone more knowledgeable than me that brushless motors' torque curves (relevant more specifically for weapons) are non-linear. Because the voltage scales with motor speed, meaning that they are not at their peak power until they reach the top of their RPM range.

Max RPM = Max V (voltage), so P=I*Vmax, with constant I (current), yields Max P (power).

Once we have a working robot to test with, I'll be able to actually figure out if this is true or not. But we designed around that mentality. One thing worth noting is that our prior weapon motor controllers, Kelly KDS72200E e-bike controllers, also add 1-2 seconds to spinup due to a built-in soft-start system to limit motor current spikes. Helpful for keeping motors alive, but not helping for drawing apples to apples comparisons.

1. I can try! It's been quite some time since I've fiddled with RR2 so I would have to re-learn controls and whatnot. Seeing many of the things being build, I figure it can't be too impossible for me to build my big boxy robot.

Do you have any kind of controllable current limiting modeled into the game yet? Trying to make a model of HUGE that drives accurately would require current limiting due to its (bad) design in 2019. It was geared for ~26mph, and limited to anywhere between 60A and 100A depending on the fight. This was based on trying to re-use under-sized motor controllers that we already owned, and cheap off-the-shelf gearboxes. This resulted in driving characteristics that were an incredibly slow acceleration up to a high speed. For example, when fighting Hypershock, we actually drove forwards running away from them once they pushed us up to high-ish speeds, since our top speed is technically faster. They just obviously had the acceleration advantage.

2. For 2020, we will be using Trampa VESC 6 Mk.3 motor controllers. Trampa controllers were spoken of very highly by the teams that used them last year, enough so that we felt comfortable making the jump. Still plenty of testing and tuning to do!

Edit: As another thought, current limiting will help a lot in-game (as well as in reality) with motor heat management. A28-400's could never be used to run a robot up to 26mph without current limiting, they would burn up for sure. But hey, HUGE isn't a bot built to push people around haha.

4


Fun story about the ampflows. When running-in our A28 motors, brand new, just running for 10 minutes on the bench with no load, they ended up hot enough to burn me.

Oof!  Are you still using them?

We haven't had any problems, but we are only running the A28-150Gs at 24 volts to push a 60 pound robot.

BTW - The girls team's version of "HUGE" (they called it "Colossus") worked really really well!  They did a thwackbot with a crowbar on the end and 22" diameter UHMW wheels.  Thank you for your help!

That's awesome! And I think the A28-150G's should work perfect in that size. A few heavyweights even boldly use them. Valkyrie has always just been 2 A28-150 motors, although it's never been tasked with pushing much. Since we used the A28-400G's, we were using the same gearboxes as well, which held up fine for 6 fights at BattleBots and 3 at Robot Ruckus (in thwackbot mode). We won't be using them for 2020 (or 2021... or 2022.......), as we designed in Maytech 8085 Brushless motors. We were swapping the weapon to those motors and decided to change the drive over as well, so that all of the spares can be double-useful.

5
Tried the build and, its great.
Its a shame that the flippers are gone, but its not an issue

Overheating is great, but imo they overheat too much
A40 motors are overheating when idle if: it is set as servo, and has limited angles

If a battery is not wired to the esc, and if you go to test area, the bot explodes, and when i go back to the lab, parts fall off

The fighting is top notch, the hits are well done, and bots dont self destruct

One thing that is broken is the selfrighting. It is kinda non functional as seen in this vid below:


Also custom arenas are gone, all the AMT made and the game made (Test arena is still selectable)

Fun story about the ampflows. When running-in our A28 motors, brand new, just running for 10 minutes on the bench with no load, they ended up hot enough to burn me.

6
The real robots are cancelled. We all come crawling back.

7
i do.

not sure why but



and like even if no one cares why arbitrary stop people from posting? its not like the discord is a good substitute anyway. obviously i agree with keeping it around as a record as well but it's still better than discord even apart from that

Discord is a trash platform where anything relevant is un-search-ably and un-sort-ably lost to time.

Thank you for coming to my TED Talk.

Someday the forum will split into RA2 and RR2 sections. Plus maybe a section for coordinating Robot Champions matchmaking with each other. Just let things run their course. GTM has been "just 6 months from death" for like 10 years.

8
Outside of nostalgia? Nah, but my nostalgia is  a pretty strong motivator, so I do care.

9
I have managed to bag the game permission to use NPC. For the time being they have let us use the T-64 motor.

But can you accurately simulate the annoyance of the holes not being mirrored on either side  :mrgreen:

10
Showcases / Re: Arcane's RR2 Creations
« on: October 22, 2019, 07:07:14 PM »
That looks amazing :D

11
Off-Topic Discussion / Re: TL:DR Ra2 is sucky
« on: August 31, 2019, 11:54:04 PM »
Here for my baby boomer hot takes since I've been here 11 years now. The RA2/GTM is dying bitchposts have been a thing since the moment I got here. It just didn't used to be from the admins. I agree with Reier. I also agree that building/tournaments is nothing like what it used to be. Whether that is for better or for worse is up to the reader's opinions, but people will always build to win. If anything, you could milk a couple good years out of standard tournaments just because the bar is so low now that it'll take years for Stock/DSL-S to get back to where it once was.

You're never going to get a million people on here, especially for a 16 year old game. And some people's feelings are going to be hurt, because that's the nature of a forum. People these days aren't used to the fact that the dimmest bulb burns just as bright on a forum. Stupid is as visible as smart, and speaks from the same platform. The key is that there needs to be admins/mods that rise above it and can help guide the ship and keep people in line.

I think it's worth it to just maintain the community you have and let its longevity and resources attract folks. Other communities have always come and gone and these new ones will go too once the people shepherding them lose interest. Everything mentioned here is based around a single person running the show, and is therefore on a timer. GTM seems to be the only place that has properly handed over the keys of power into multiple successions of admins/mods. People will come once it is the only playground to play in once again.

GTM was my creative outlet for robots for years, and filled a niche when I couldn't build in the real world. I think it has the potential to serve that purpose for people still. But it's tougher since it seems like the site as a whole is now apathetic with regards to real combat bots, or at least is discussing them on other platforms. The jump from virtual to real isn't encouraged anymore. There used to be a much more thriving community here of people discussing the latest episodes of all the shows, or past/live events. The more people who make that jump, the better the outside's view of this community will be.

Thank you for coming to my TED talk.

tl;dr: life sucks, and the opinions of sad zoomers are irrelevant, even if they're just as loud. Don't be an admin unless you care, and go build a real beetleweight. It's like $300 and you'll learn a lot.

12
Real Robotics Discussion / Re: Robotics Questions MEGATHREAD
« on: August 20, 2019, 09:13:07 PM »
It would probably be lighter just to find a motor appropriately oversized to deliver both speed and torque. As for motors, if you want peak power, big brushless inrunners are probably where it's at. Just need to get the gearing right.

Also be careful testing because spicy drive becomes on-fire drive pretty easily.

13
Existing Games / Re: Robot Champions
« on: August 20, 2019, 09:11:03 PM »
Backed it. I had too much fun playing the demo. It's not RA2 but it's fun in it's own right and serves a purpose of bringing combat bots to the masses. The success of this game is good for other games and for the sport overall. Happy to see it's already almost a third of the way to it's goal.

14
A servo motor for heavyweights. It would be really useful, to build lifters and clamps.

It's worth pointing out that this does not exist in reality. Every robot you see is running large gearboxes, geartrains, or chain/belt drives to gear down continuous rotation motors enough to be effective drive, or effective at lifting an opponent.

15
Off-Topic Discussion / Re: Apex: Invitational
« on: May 23, 2019, 05:35:25 PM »
Man wait until people find out that Battlebots don't just let anyone who turns up compete. Folks are gonna FLIP

You'd be surprised tbh

16
Real Robotics Discussion / Re: Battlebots 2019 Discussion thread
« on: May 12, 2019, 08:45:05 PM »
Hydra is hot fellas

I'm still convinced it just runs on magic, and the paintjob only double-confirms that fact.

Just want to say to the builder of HUGE, Somebody, but happy birthday

 :party

17
Real Robotics Discussion / Re: Battlebots 2019 Discussion thread
« on: April 05, 2019, 03:14:59 PM »
It's the exact same thing

18
Real Robotics Discussion / Re: Robotics Questions MEGATHREAD
« on: March 13, 2019, 06:34:24 PM »
Do you guys know any in-depth combot making guides that are up-to-date? The Riobotz one is from way back in 2009 and the world has changed a lot since then.

The basics on the whole have not changed much. Components and methods have more-so. The discussions of brushed vs. brushless motors and how specifically to construct a robot are generally lost on someone without the understanding of robots and engineering that it provides. It taught me everything I needed to know in about 2016 to get me started, and know the questions to ask to get myself up to speed.

Other good resources:

Robert Cowan's youtube channel
https://www.youtube.com/channel/UCPOTPYuDsKnXP9I-ph4yMgg

Charles Guan's legendary Instructables guide
https://www.instructables.com/id/How-to-Build-your-Everything-Really-Really-Fast/

19
Real Robotics Discussion / Re: Battlebots 2019 Discussion thread
« on: February 10, 2019, 11:21:58 AM »
The bar looks heavier than the body and it doesn't look stable.

Stable robots are for stable people

20
Robots Showcase / Re: Team *Placeholder*
« on: February 04, 2019, 01:16:08 PM »
Nice!

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