Drivetrain stalling(?) Is this electrical or mechanical?

[Nirnaeth]

Here are some videos of it.

http://www.youtube.com/watch?v=MyhQGC7g_9A

http://www.youtube.com/watch?v=eTmO7Dx8_Bs

So we decided to clean out all of our control board components with compressed air after one of our jaguars started to smoke earlier today. When we reassembled the board, our drivetrain started to experience this issue. Basically, if we slowly accelerate, it seems to be fine, but when we punch it, it seems to stall. Any clues?

[548swimmer]

On principle, it can't be mechanical .

But honestly, it seems like you have unhappy jaguars. Since the chain meshes nicely with the gears, its highly unlikely that the stall is caused by a mechanical bind.

If you want to, you could write a code that limited the acceleration to the acceptable level.

[Cecil]

It looks like your Jaguars are giving conflicting signals, and are reversing very quickly. Are you using any PID on them?

[BJT]

as a mechanical guy, I think those cims on the left side tranny don't look right. they should be lined up nice and parallel coming out of the trannys. they seem to angle away from each other. could there be a problem with the assembly of the tranny?

[DavidGitz]

I'm going to reference one of Al's posts:
-Put the robot on blocks: With power removed, manually rotate each side. Is there a difference? Does one side sound different? I assume you are using the stock Toughbox configuration, so the wheels should be fairly easy to turn and turn smooth.
-With the robot still on blocks: "Hotwire" (i.e. keep the main power removed and run a battery to both motors, observing correct polarity) each side again looking for obvious clues. If you have a DC Clamp (or some way to measure electrical current) measure current going to each motor. I believe with no load applied it should be around 5-8 Amps.

Other questions to ask:
-Did you grease the transmissions? Did you assemble them correctly? We've had problems in the past with the Toughbox transmissions with the lock washer (don't know the correct term) that holds the gear in place coming off and getting stuck in another gear. If you get any indications from the above that things aren't "perfect" I would take apart the Toughbox's and make sure everything is fine.

EDIT: Sorry, I didn't watch your second video till just now. It definitely sounds like your CIM motors are stalling. I would still go through the above tests to make sure it's not a mechanical issue. If those tests look fine, there might be something in your programming going on. But it sounds like a mechanical issue to me.

My $.02

Another Edit: That sound is not your CIM's stalling, I don't know what I was thinking last night. If the CIM's are stalling there will be a lot longer pause between the sound as the breaker will have to reset and that will take about 1-2 seconds. It's definitely something binding or stuck in the Toughbox.

[Steve_Alaniz]

I think... I THINK you have a wiring error... I've been trying to see which jag goes to which motor. From the first video... the black jags run the same direction and the gray run the opposite of the black. However... you seem to have the outputs of the black jags opposite each other. So that means one black jag running the left side and one black jag running the right side. The corresponding gray jag of each side would have to have the output opposite of the same side black jag. So I think you need the jag like this:


Battery

one side

one side
other side other side



but not sure this explains why it works correctly slow unless one type jag overpowers the other type at low speeds... no info on that.


Anyway... for a test... set the bot on blocks, disconnect the pwm from one jag from each side and see if you get what you expect in motion.


Hope that helps... I have a similar problem but that usually ends up being my own stupidity... can't be helped... I AM a professional after all...


Steve


(Now that I've said something... some genius will shoot down all my ideas... )

[Hawiian Cadder]

that sounds to me suspiciously like you have some key-stock that has slid into the gears and is being ground up. if it is not the key-stock then i bet it is a wiring issue.

[Chris is me]

It sounds VERY suspicious and mechanical.

The CIMs on the left look incredibly crooked. They should be straight as an arrow and mounted as tight as possible onto the polycarbonate.

Check your CIM pinions and see if you threw your machine keys.

Upon watching the second video, it seems obvious / apparent that there is a HUGE amount of binding and mechanical problems in your gearboxes.

[Nirnaeth]

Ok, so everyone who seems to indicate that it's a mechanical problem seems to be point to the left side. However, the right side is doing the same thing. We disconnected the motors from the jaguars and directly connected it to a 12V source, and they ran fine. (at least on the right side. Haven't had time to do it with the left). Are the lights on the jaguar supposed to rapidly blink like that? It seems like we're not getting enough current?

[RyanN]

Thinking simple...

The gray Jaguars are going into error condition, or so it appears. The black Jaguars seem to be cutting out for some reason (tick tick tick tick in the 2nd video).

1. Low battery voltage.
2. Loose wiring on terminals.
3. Conflicting signals.

I'd recommend using Y-PWM cables to split the signal. If you have 2 separate signals coming out of the digital side car for each side, then you are just asking for trouble. Two of these Y-cables should have been provided in the KOP. Please use them.

[Alan Anderson]

To see if it's a wiring/code problem, remove all the circuit breakers from the drive motors' speed controllers. Insert only one at a time and make sure the wheels run in the direction they should when you move the joysticks. From the descriptions, it sounds like you might have motors fighting each other.

[gorrilla]

Make sure you have 12volt power to the digital sidecar from the PD board!

We had this same problem and spent five days taking everything apart to fix it.

it was getting 5v power from the CRiO cable, so we'd go slow and everything would work, but once we used more current than was going through the white cable it would stall, essentially turning itself off from lack of power. we also fried a jaguar doing this.

[StealthMentor]

We are using brand new toughbox nanos on our drive train this year, and just recently started trying to drive. We noticed a clicking, and vibration coming from one of the toughbox nano gearboxes. Upon inspection discovered the large gear that meshes with the cim motor drive gear was malformed, one of the teeth was wider than the rest causing binding, and noise, about 30 seconds of running the jag fails and blinks red. We replaced that gear with one from an old toughbox and it works perfectly now.

Take your transmission off and try to turn the wheel by hand, if the resistance is variable (gets very hard or stops entirely at one point) then you probably have a similar issue.

I have seen several posts with similar problems, I am going to try to reply to all of them.

[Al Skierkiewicz]

Michael,
Have you corrected your problem here? The clicking sound in your video makes me want to think circuit breakers are tripping. Try removing the breakers from one motor on each side and try running and see what happens. If everything runs, try removing the breakers for the other motors and return the originals and see if it runs. If both of these tests are good, you have two motors running in opposite directions in the transmission.
As another observation, if you swao the location of your battery and your PD, you will shave off feet of wire between your drive and the PD giving you extra power.

[DavidGitz]

Al - Could it really be the Circuit Breaker's resetting that quickly? I count at least 10 resets a second (approximately). According to the Snap Action specifications http://www.snapaction.net/pdf/MX5%20Spec%20Sheet.pdf
this reset time equates to roughly 500% overload on the Circuit Breaker, which would be 200 Amps. I acknowledge that my times/percentages may be off, but wouldn't the 120A CB be resetting as well? And if the motors work sometimes, (assuming they are using it with a PWM Y-Cable) doesn't this make this argument valid as it does work sometimes (at low rates of acceleration)?