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Unread 04-03-2012, 19:19
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Re: Your take on CAN...

Quote:
Originally Posted by JABot67 View Post
http://www.youtube.com/watch?v=Z4Id9IR_HCU

Consider this match video. It never seems like we are "beating on the battery". In fact, it looks like our driver is being very meek in this final match. Perhaps there was a problem from the very beginning, like a drive jaguar on both sides not working. However, our problem occurs around 1:20 in the video, when the right drive gives way.

We have omni wheels in the front of our robot that can be deployed for easier turning; they are deployed for the majority of the time except when we are pushing another robot, aiming to shoot, or trying to balance the bridge. When these omnis are deployed, only our back wheels are driven and we do not get a situation where a bunch of wheels are trying to drag across the carpet. Therefore, I believe that our drivetrain should not be demanding a ton from the Jaguars and the battery. Perhaps it is an electrical problem.

We will definitely work through this in the next couple weeks and find a solution. Thank you for helping us and pointing us in the correct direction. Nothin' like having a robot that almost works!
The problem with this analysis is that it assumes that the only forces that act on the drive train are a driver with a 'lead foot'.

You could have a misalignment, a jammed chain, a stuck bearing (or no bearings), a jammed wheel, or even something wedged in your gear boxes.

It's not just a question of physical speed, there's also torques and accelerations versus momentums and inertia.

You can read the Jaguars to get the current so I'd put it up on blocks, run it and see how much current you flow like that. Then put it on similar carpet and try it. Also if you have the tools you can measure the current with your own small high wattage resistor in series and a voltmeter or even a DC compatible clamp on current probe if you doubt the Jaguars (just remember that that resistor must be small or it'll lower the performance of the Jaguar and motor by you adding it).

Also I should point out that last year we did have a pair of bad CIM motors. So you might want to try some other CIMs, perhaps you have one with an issue (they are pretty reliable but it happens).
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