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#1
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paper: Window Motor Lockups: Causes and Solutions
Thread created automatically to discuss a document in CD-Media.
Window Motor Lockups: Causes and Solutions by ratdude747 |
#2
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Re: paper: Window Motor Lockups: Causes and Solutions
I'd like to note that there was previously at least 1 other pictorial guide on the pin removal procedure, as I learned the procedure from it last year. That said, when I was asked about the procedure this year, I could not locate it on CD-Media, so I decided to re-create and expand on it.
Any suggestions/corrections are welcome. |
#3
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Re: paper: Window Motor Lockups: Causes and Solutions
We steered our fall 2011 independant swerve with windows 1:1 with gray jags without issue.
We steered our 2012 swerve with windows geared UP 1.3:1 with victors without issues. We've been trying to replicate the issues others claim to have, but we have been unable to. |
#4
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Re: paper: Window Motor Lockups: Causes and Solutions
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In that case, I was told that the intermittent issue stopped occurring after an emergency swap from serial-CAN to PWM. I am pretty sure that all the Jags on that bot were black Jags. What method are you using to control your motors? |
#5
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Re: paper: Window Motor Lockups: Causes and Solutions
Standard pwm
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#6
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Re: paper: Window Motor Lockups: Causes and Solutions
Ah. Perhaps CAN usage is related to the occurance of the lockups. If emperor swerve ever goes to CAN, I suggest preemptive locking pin removal.
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#7
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Re: paper: Window Motor Lockups: Causes and Solutions
We had lockup issues this year on our hood. Our controls operators was able figure out a pattern to get it to take commands again after it would happen but it was an issue. I thought it was a myth for awhile as well but I can assure you that it does exist.
Thank you for the tutorial. |
#8
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Re: paper: Window Motor Lockups: Causes and Solutions
But locking pins would seem advantageous in such an application. The expected load is not likely enough to strip the gears and maintaining orientation of the module mechanically will reduce load on the motors.
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#9
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Re: paper: Window Motor Lockups: Causes and Solutions
Most Modules do not have that issue, as the wheels are evenly centered with the module's axis of rotation. If the modules were more like casters, then there very well could be a backdriving issue.
Last edited by ratdude747 : 05-06-2012 at 01:26 AM. Reason: Misread post, Doh! |
#10
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Re: paper: Window Motor Lockups: Causes and Solutions
We used window motors with the pins for steering at least one season. The only time it was a problem is when we slid into something with the wheel turned sideways. If the output of the gearbox is turned (like trying to pry the window down on a car), the pins would lock enough that the PID loop output couldn't turn it. Steering into the lock would always unlock enough to recover so it wasn't a big problem but since we've been removing them driving smoothness improved noticeably.
Thanks for getting this where more teams can find it. |
#11
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Re: paper: Window Motor Lockups: Causes and Solutions
You are very welcome.
------------------- I uploaded a revised version. The previous version had an admittedly blatent grammar/wording error that slipped through editing... OOPS! Content wise, it is the same, as any involvement with CAN is at this point speculation. |
#12
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Re: paper: Window Motor Lockups: Causes and Solutions
Larry,
I believe the problem manifests itself when there is enough backlash in the system that the motor can vibrate with the output current waveform generated by the Jag. Systems such as steering in a crab drive system tends to damp any vibration that might occur. From those that have reported to me or here on CD it would seem that more than half of the teams that use the Jag/window motor combination experience the problem. As reported, the difference between the left and right hand motors has more to do with the wire size the armature is wound with than actual performance. The lefthand motor getting significantly more use in standard operation then the right. Nice job on the paper and the pictures it contains. This should allow more teams to overcome this small shortcoming by removing the pins. I would suggest you add the length of time this operation would normally take. Since it is so easy, more teams would take your advice and remove the pins. I would suggest that teams also keep the pins in a safe place so they can reuse them if needed. |
#13
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Re: paper: Window Motor Lockups: Causes and Solutions
Quote:
Quote:
"Performance" may have been the wrong word; I was trying to imply that the motors weren't quite compatible with eachother so to speak. Any suggestions on a better word or phrase to use? Quote:
Since I currently am not a permanent mentor (the photo shoot was by special request), I personally do not forsee myself getting a chance to time the job. Perhaps other teams that perform the procedure could post about how long it took them (I'd take a guess but in that shop, time flies). I hadn't thought about that... Noted. I may add that to a future revision. |
#14
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Re: paper: Window Motor Lockups: Causes and Solutions
It's good that this came up again since some time has pasted. For the 2010 season, our team developed a swerve 4 wheel independent drive, 4 wheel independent steering continuous rotation bot. We used the Denso window motors for the steering. We had several problems. It wasn't until the software issues were dealt with that we began to notice a problem with the window motors locking up and cutting out by the thermal protections built into the motor. We found out about the locking pins and removed them. Our steering motors were more responsive and ran cooler. Note that we were using them for positioning controlled by a PID. The window motors were driven by a Black Jag. Even with the pins removed we had intermittent shutdown issues. The problem was not full resolved until we replaced the black Jags with Victors. Since going with the Victors we have not had a problem. We still drive the bot to this day and have not had another incident. After this experience I would suggest that teams that are using window motors for a positioning application remove the locking pins and use a Victor not a Jag. For 2012 we used a window motor with the pins in for our bridge lowering mech driven by a Victor. No locking problems. The PTC thermal over load did shut down the motor when it was needed preventing the motor from releasing the magic smoke. The pin removal is not needed for ever application. However, There does seem to be a problem with the Jags. I think the high switching frequency of the Jag leads to self heating of the PTC. Also note that I believe the Jags for 2010 used locked anti phase control of the fets. The recent Jags I believe are low side switchers using sign magnitude modulation. Never tried a recent jag with a window motor. Ever team should Know of this issue so it can be dealt with if it arises. Also important since First has allowed other automotive units to be used this year. Many of the common units do have PTC protections built into the motors. The interaction of PTC's and jags should be followed and notice given if problems arise.
Link to original thread on Chief Delphi. It's rather long showing the round about discover of the problem. http://www.chiefdelphi.com/forums/sh...ad.php?t=83973 Link to our team's website on the problem. http://wiki.team1640.com/index.php?t...r_Locking_Pins |
#15
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Re: paper: Window Motor Lockups: Causes and Solutions
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I hope making my own guide isn't beating a dead horse... ![]() |
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