Author Topic: Team Brain Damage  (Read 74860 times)

zacodonnell

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Re: Team Brain Damage
« Reply #300 on: January 21, 2018, 08:45:51 pm »
Ok, initial flip and drive testing is done. The flips are a little weaker than I want, but I think that's because of the cleats and frame being messed up. I have to replace the side frame rails to fix the damage done by the Balhogs saw bot last year.  The sensors work well and turn the magnet off ~11ms before the arm strikes the rubber stoppers on the frame. I've done a little more tuning since I made the video to make that window as small as possible. I put a white stripe on the flywheel so I could see how fast it's going. Mostly for academic and efficiency reasons - no practical implications yet. Someday I'll actually use the info probably.

The robot also self rights reliably, even at very low speeds, which is great. The sensor should reduce the over-throw on the self right attempts and prevent wasting the entire flywheel when I do it.

Now the bad news:
The drive system is flaky. The left drive motor seems to lose track of the signal and stop working intermittently. Sometimes a power reset fixes it, sometimes not. Sometimes it never connects, and other times it is working for a while and then stops. Could be a loose wire, but I'm betting it's an issue with the radio signal and the controller being picky about arming. I also have witnessed a few "runaway jitter" scenarios where the motors start jerking forward and back semi-randomly. They seem to come when spinning up the flywheel most often, but not always. It could be some kind of electrical noise but it is really bugging me. I'll play with the signal leads and extend the deadbands on the controllers to try to fix it. If I can't in pretty short order, out they come and back in go the old 550 motors. When the drive is working it is WAY FAST though. My little 4x8 test box with a dusty floor doesn't let me really see though.

I'm also about 5 ounces overweight right now. I knew it would be over, but I was thinking 3 or 4. I think I can still find the weight, but yuck. Worst case I could go to lipo batteries for moto, but I want to make sure the new drive motors work out before I do anything drastic.

Walkthrough video of some of my testing:
https://www.youtube.com/watch?v=Izz1zTKJPUk&feature=youtu.be

And self righting:
https://www.youtube.com/watch?v=At8CjyNKJIw

-Zac

Koolaid64

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Re: Team Brain Damage
« Reply #301 on: January 21, 2018, 10:55:49 pm »
I have had some issues with mixing and brushless drive.  For some reason it tends to not get along very well for me. What are your settings for the redbricks?

-Kyle

zacodonnell

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Re: Team Brain Damage
« Reply #302 on: January 23, 2018, 08:37:58 pm »
I decided to try calibrating the drive speed controllers with my transmitter stick to see if that would help before I rip them out of the bot and redo the settings. I'll still probably have to do that because I didn't change the low voltage cutoff and I'm running 5S A123, which might look like a really tired 5S lipo or a healthy 4S lipo to the controller. I don't want it "saving me" and costing me the fight.

The calibration made a huge difference. Before I did it I could easily get the left side drive to stop working. It was like it lost the signal from the rx and wouldn't pick it back up. Even turning the bot off and back on didn't always bring it back. I think the neutral signal from the tx was on the very limit of the arming line for the controller, so it didn't spend much time "in the window" to re-arm it. Playing with trims and the like didn't help much, though I could sometimes get it to start going and then stop.

Once I redid the calibration (one side at a time, still with mixing turned on in the TX) it seemed to fix the problem. I did a 2-3 minute test with the weapon pod out of the bot and it performed fine. My little wimpy test box isn't big enough to actually test it, but I could drive back and forth trying to not hit the walls or the end. I'll need to practice more to get used to it. I turned the steering channel down to 50% to avoid oversteering and that helped a lot. Spinning in place with the flywheel going and the steering channel all the way up will be some kind of silly gyro dance I'll bet.

video:
https://youtu.be/UE2u8fXp_nU

-Zac

zacodonnell

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Re: Team Brain Damage
« Reply #303 on: January 23, 2018, 09:47:22 pm »
A little more fun with programming the drive controllers tonight. Need to actually make a change that I can verify as it seems like the tool reports success even if I don't attach a controller.

-Zac

zacodonnell

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Re: Team Brain Damage
« Reply #304 on: January 28, 2018, 07:45:05 pm »
I tracked the issues down. It was painful and time consuming, but eventually I was able to get one-wire programming of the controllers to work from my laptop. There was some wrestling with the drivers and settings involved but in the end I'm happy with it. I still need to prep the other two controllers I got as spares since I'm sure the motors could do bad things to the controllers if they get jammed up.

I did some more weight reduction this weekend too. Hollow front axles, shorter drive axles, and remade the side rails with more pockets. I even put a 1" hole in the outriggers now that I know 1.5" thick outriggers were *almost* enough (after balhogs chopped my existing ones in half)

Adding up all the bits of the bot (didn't have time to assemble it) shows 29.996 lbs.  Not too shabby!

-Zac

rcjunky

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Re: Team Brain Damage
« Reply #305 on: January 29, 2018, 01:25:22 am »
And the Moto scale historically has been in 0.5lb steps so you have 4oz grace ;) 3 weeks till Moto
Andrew Burghgraef
Canadian Carnage Robotics

zacodonnell

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Re: Team Brain Damage
« Reply #306 on: January 29, 2018, 10:19:26 pm »
More work on the bot tonight. The left side drive system is still giving me fits though. The right side has worked this entire time, so I'm starting to suspect it's specific to either the wiring harness for the left side or the controller. I have a couple of backup controllers to try, so I'm going to swap one of them in and replace all of the signal wiring between the controller and the receiver for good measure. I prepped the backup controllers tonight and the glue is drying now. Here's a testing video with some comentary. Toward the end I started to think it was mechanical instead of straight electrical noise...
https://youtu.be/Xd7sWcAbFAs


The outriggers are bending already, so maybe that weight reduction hole in the front was a dumb idea. I'm going to try to remake the cleats as pieces of angle tucked in the front corners to try to take some of the leverage off of the outriggers. I tried a flip without cleats but that was pretty scary. All I can say is Hooray for Lexan! This is the reason I have a door on my test box :)
https://youtu.be/miDasiB7Heg

-Zac

Koolaid64

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Re: Team Brain Damage
« Reply #307 on: January 30, 2018, 10:19:31 pm »
Looks like the drive is being pretty fickle. That's annoying for sure. When it does work, it works great. When it doesn't, nothing is more frustrating.

-Kyle

zacodonnell

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Re: Team Brain Damage
« Reply #308 on: February 05, 2018, 08:57:39 pm »
I agree, it is being a bit frustrating. I didn't have any time to work on it last week either. If I can't get it to be pretty reliable before the show I'll swap the old setup back in and try again next time. My biggest fear is thinking it is working and having it flake out on me during a fight.

Hopefully more to come on this tomorrow night.

-Zac

zacodonnell

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Re: Team Brain Damage
« Reply #309 on: February 06, 2018, 09:45:57 pm »
I think I traced the drive issues to a loose receiver wire on that drive controller. I was able to reproduce it by tapping on the wiring harness / controller while trying to drive. At first I thought it was something internal to the controller, but when I went to swap the controller out I found an untaped rx wire extension in the chain that had the connector mostly pulled out. My extensions have a little plastic clip that is supposed to hold the parts together, but I always tape them anyway. Looks like that's a good plan as this one appears to have separated just from my test flips. I got it put back together and could no longer reproduce the problem on the bench.

I moved on to planning out the updated cleats that will hopefully not bend the frame as much. They're going to be angle brackets that share the load between the front and side rails and extend much less far from the robot. I'm hoping that with good cleats I can actually cut the outriggers way down, which would give me better reach on the opponents as well as providing the weight for the beefier cleats. I'll work on that tomorrow or Thursday. With any luck the snow will force work to cancel :)

-Zac

zacodonnell

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Re: Team Brain Damage
« Reply #310 on: February 07, 2018, 10:12:21 pm »
I got the new cleats cut out and mounted tonight. They came out ok, although I didn't have time to test them yet. There are a couple of things that might make them more effective but I want to watch the video before I try anything else. I took some pictures and also uploaded a few of the frame modifications I did before.

https://plus.google.com/photos/107279152885550274671/album/6510901572747399649/6520015569117808946

-Zac

Koolaid64

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Re: Team Brain Damage
« Reply #311 on: February 08, 2018, 09:18:41 am »
Looks like it should work. It will defiantly help you get under opponents.

-Kyle 

zacodonnell

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Re: Team Brain Damage
« Reply #312 on: February 08, 2018, 10:22:14 pm »
More fun with cleats tonight. The shorter cleats work fine once I cut the outriggers off. In fact, in one of the tests the robot actually leaps forward after flipping the target. I'm not sure where that reactive force came from unless it was spring tension built up in the frame... Any thoughts? It makes for a cool flip though :)

Video
https://youtu.be/7al5lmLHymM

Pictures:
https://plus.google.com/photos/107279152885550274671/album/6510901572747399649/6520388756132149346

-Zac

Koolaid64

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Re: Team Brain Damage
« Reply #313 on: February 08, 2018, 11:26:51 pm »
that frame flex is pretty intense.

-Kyle

zacodonnell

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Re: Team Brain Damage
« Reply #314 on: February 10, 2018, 07:39:27 pm »


I did the last bits of maintenance on the bot today. Replaced the rope, cleats, return bungee, and bumpers. I also made spare bumpers (I have lots now). I'm hoping the sensors drammatically reduce the need for me to swap bumpers every match, but they're not that expensive or difficult so I figured I'd have extra. I still need to swap the new wheels in. These are looking pretty rough after my testing. My plan is to organize my stuff and paint stuff tomorrow morning, then pack it all up in the evening.

I'm very satisfied with the self righting even at low flywheel speeds. I think the sensors are the big difference maker there because they ensure it goes to full extension regardless of how long the magnet has to be on. The flips in the video are so-so but the target is backed right up against the test box wall so there isn't really anywhere for it to go. The angle of the flips is definitely more forward than up, but it makes for some good shots into the plastic in front of the judges :)

Pictures:
https://plus.google.com/photos/107279152885550274671/album/6510901572747399649/6521088089889470914

Video:
https://youtu.be/uZRkuOkTNMA

-Zac