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Messages - cjbruce

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41
The 28May2020 Bleeding Edge Build is up:

http://www.robot-rumble.com/bleedingedgebuilds/

Just a few tweaks from the build two days ago:

[Bug Fix] Pause menu pauses now.  [TODO] The rest of the menus still need to be consolidated between the different arenas.

[Bug Fix] Belt pulleys and chain sprockets were improperly scaled in some cases.

[Bug Fix] Scaled down the moment of inertia to 30%.  This should make Poison Arrow drivable.

[Bug Fix] Fixed scale of the high speed spinner collider.  It was set to 5% instead of 95% of the spinner's maximum radius.

[Bug Fix] "Reset Bot" in the test cage now resets the telemetry as well.

[Changed] Changed the description for the A28-400 to say "middleweight".


42
Finally gave the build a proper go, and not a fast check.

So about the bite. I feel like there is a delay between a spinner's tooth collides with the opponent, and when the opponent is sent flying
Gyro is ok, not the best, but im sure that it works like that in irl

For the next build I'm reducing MOI to 30% of its original value.  This should make Poison Arrow very difficult to drive at 8000 RPM, but not completely impossible.

Ive seen that titanium is added ingame, its all there for placeholder or? Atm It has no sparks unlike real titanium which sparks like crazy (its all about them spark effects that are melting the cpu)

Titanium exists, but spark and bite are still on my to-do list.

I cant seem to break parts off, i assume damage is off because of the experiments with the spinner bite and gyro

Correct.  We need to get bite working properly before we turn damage back on.  Damage is very dependent on bite.

43
min, I'm convinced now.

I finally had a chance to sit down and play with the incredible Poison Arrow model you created.  First off, wow!  It is amazing!  The drum is slightly underweight and you geared it a little further down than the real thing, but wow, nice job!

There is definitely a problem with the wheel lift when the drum gets up to speed.  To me it looks like the lift is occurring correctly.  The problem is that it is not setting itself back down when you reverse the condition that created the lift.  This is not physically correct at all. 

I have no idea where the problem is, but one solution is to include a script to reduce the Moment of Inertia.

44
Yea it is a thing. When I made E-max (the 4WD drum bot) into a 4WD disc spinner without changing the weapon weight, the turning issue caused by gyro just disappeared.

But I think 2WD verts still have some unsolved problems. Just look at my post above.

Thanks for checking that.

As far as 2WD drivability issues, there is definitely something weird going on.  The only effective solution I have found is to put all of the weight right over the wheels.  I don’t know why this is true.  That’s the most frustrating part.

45
min,

That's a great observation!  A disc and a drum with the same radius and the same mass distribution (automatically true for the game because I'm lazy) will have the same MOI.

From the point of view of gyroscopic effect, the length of the drum should make no difference. 

Try the following using the Run Amok Spinner Kinetic Energy Calculator:  http://runamok.tech/RunAmok/spincalc.html

Thin Disc:
Density = 8000 kg / m^3 (approximately steel)
Thickness = 25 mm (1 inch thick)
Radius = 100 mm (8 inches in diameter)
Mass = 6.28 kg
MOI = 0.0314 kg * m^2

Thick Disc (a.k.a. short drum):
Density = 2000 kg / m^3 (approximately aluminum)
Thickness = 100 mm (4 inches wide)
Radius = 100 mm (8 inches in diameter)
Mass = 6.28 kg
MOI = 0.0314 kg * m^2

The thin disc and the thick disc have the same radius and the same mass, therefore they have the same MOI.  They should have the same gyro lift when you turn.

We can test this in the game by creating a disc weapon and adjusting its properties to maintain a constant spinning mass while varying the length of the drum.  No matter how wide you make the drum, as long as the mass and radius stay the same it should drive the same.  If the gyroscopic effect is different then that is a quirk with Unity's implementation of PhysX that needs to be addressed.

46
RE: Gyroscopic Effects

 For this build I finally removed the “fudge factor” that was included to reduce the moment of inertia if spinners.  MOI in the February 16th build was somewhere around 10% of what it should have been.  That code has been eliminated.

I need to take a deeper look now to verify whether or not the amount of wheel lift we are seeing is true to real life.  It’s time to whip out the calculator! 🙂

47
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.

48
Min,

I just had a thought about gyro.  If you were driving the real-life Minotaur you wouldn't push the stick all the way left or right if you felt the robot lifting due to gyro.  You would back off the stick slightly to try to keep the robot flat.  Likewise, you would be continuously adjusting the motor speed so you weren't going full speed all of the time.

If you don't have a game controller with an analog stick at home, you can simulate this input by hooking up the drive motors to 8 or 12 volts.

If you were to try a reduced drive voltage, how does it feel when you are turning with a reduced input signal?  Is gyro controllable?

49
I’m glad you like the smoke!  It was supposed to be in the last build but I accidentally disabled it right before we pushed the builds.

Spinner impacts are back on my list!  I need to look at spinner bite again now that the colliders have been reworked.

50
New bleeding edge build is out (26May2020)!

[Bug Fix] Fixed crashing bug when a motor is not connected to a battery.

[Bug Fix] Fixed problem where the game tried to find a connection on motors that don't have connections when spawning for combat.

[Bug Fix] game tried to access removed components while looking though the wiring system.

[Bug Fix] sometimes the game changed all channels in the receiver when the player changed only one channel.

[Bug Fix] Arena Menu only showing 1 Custom Arena

[Added] Added A28-400 motor.  This is a bigger version of the A28-150.  Somebody, I'm looking at you! :)

[Added] Motors smoke when their temperature is greater than 115 degrees.

[Potential Bug Fix] Spinners should self-right now.  This needs to be tested across a bunch of robots.

[Tweaked] Increased speed at which the high speed collider is enabled from 30 RPM to 120 RPM. This should make things look a little more realistic.

51
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’m 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’t 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?

52
Not sure.  It might be for an engineering camp this summer.

Oh, i thought it would be sooner, but gladly its not as im busy, and will be for a couple of weeks.
Hosting a tournamet via parsec may or may not be a problem, depending on the ping/input delay, as if i were to host, i would be hosting from EU. I had success hosting to US people so im not that worried.

The plan is to run the host on the computer at the college.  They have a VR gaming PC and a high-bandwidth connection.  Everyone, including the host, would be within the same city.  I just wanted to know what sort of issues we are going to have if we start advertising this as a thing that people can do with the game.  I would love to open it up to students, but I'm a little scared of the logistics -- parents would be paying money for the experience, and it needs to go well.

53
Not sure.  It might be for an engineering camp this summer.

54
Hey guys,

With schools shut down due to COVID here in the US, we were just asked if the game could be used in "virtual summer camps" to teach about robotics and to hold virtual robot combat tournaments.  How do you guys feel about using the game with a bunch of kids and hosting a tournament via Parsec?  I know that we do it here with a bunch of die-hard folks, but is it ready for a bunch of students?

55


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!

56
http://www.ampflow.com/three_inch_high_performance_motors.htm

I'm not sure what the fan-cooled motors' track performance in robot combat is like though.

The usual solution is to gear the motors down to keep the temperature low.

58
After a few tests, I suspect Aftershock's turning issue was not cause by gyroing. I've test some more vertical spinners inside the test cage, and found issues like:
Aftershock's turning issue happened not only when the weapon was on, but also when it was off.
Magnetar's was quite fast at first, but you could actually see it moving more and more slowly.
When Poison Arrow was going to turn, something in the air blocked it from turning.
(All issues above happened when weapon motor's off)


And as you said: There's much more gyro in this build, but I think it's a bit too significant. you can see it on Poison Arrow. It just start gyroing madly even when the drum is 1000rpm, which is definitely unreal.
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Ah!  There is another effect happening that is new in this build: Motor winding resistance increase as temperature increases.

I haven't looked at the robots yet, but I suspect that as the drive motors are heating up their resistance is increasing.  As this happens, the motor current drops.  This reduces the torque.  I suspect that I might have a typo and/or miscalculation that is causing this heat increase -> torque reduction effect to be much too strong.  I'll try to take a look today.

59
You are welcome!  Thank you for making these great robots.  It makes development so much faster when we have great designs to work with.

One of the big differences with this build is that all of the spinner “scaling factors” have been eliminated.  This means that the moment of inertia is now what it should be for something rotating at the indicated speed.  The result of this is that gyroscopic effects are now much more significant than they were before.

60
The new build is really great and the electronic system is awesome, the hits inside the fights are back to the right position as well. But there're some issues for driving in this build.
For 4WD vertical spinners, when the weapon motor is off, the bot works fine and turns fine, but when the weapom motor's on, the bot could only run in circles instead of turning.

Oo!  That's neat!  I just checked it out in the Unity editor to see what is happening.  Once the spinner gets up to speed it has so much angular momentum that it is lifting E-Max's inside wheels off the ground during a turn.  This means that only the outside wheels are in contact with the ground.  The outside wheels push the robot forward, but the inside wheels can't push the robot backward.  This means that the robot can no longer turn in place.

2 robot design solutions exist to this:
1. Reduce the angular momentum of the spinner.
2. Increase the wheelbase.

I verified the numbers for E-Max's gyroscopic effect using this online robot combat gyroscopic effect calculator:

http://runamok.tech/insanity/gyroscopiceffect.html.

These are E-Max's measured values from the game:

Drive Train Width: 700 mm
Drive Motor Speed: 370 RPM
Wheel Diameter: 150 mm
Robot Mass: 131 kg
Weapon Mass Moment of Inertia: 1.06 kg-m^2

Using the numbers above, I get a maximum weapon speed around 1000 RPM before the inside wheels lift off the ground.  1000 RPM is pretty slow for a drum like this.  Maybe try increasing the width of the wheelbase?


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And for 4WD horizontal spinners, it goes to the opposite, run in circles when the weapon motor's off, and turns fine when the weapon motor's on.

Here are the bots.
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I see this happening in Cyber Storm 2.  It appears that the weapon is digging into the ground a little bit and acting as a pivot point for the two wheels.  When you send a signal to turn right or left that creates a rotation about an axis that it shifted toward the axis.  At least that is my guess.

I also suspect that when the spinner gets up to speed it the angular momentum of the spinner tends to keep the whole robot flatter so the "digging in" effect above is reduced.

Maybe either a smaller spinner, or a two-wheeled Tombclone design?

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