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We designed this drivetrain having never seen on octanem drivetrain before. We could push almost every robot we played. I was really quick shifting and worked great!
Discussion
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19-04-2014 03:38
cbale2000
Re: pic: our octanem drive
Probably the first of these I've seen using 6in wheels. Seems like this would be a lot simpler than a lot of the other ones posted here too.
19-04-2014 11:16
zinthorne
Re: pic: our octanem drive
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Originally Posted by cbale2000
Probably the first of these I've seen using 6in wheels. Seems like this would be a lot simpler than a lot of the other ones posted here too.
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19-04-2014 15:48
Toa Circuit
Re: pic: our octanem drive
Any issues with wheel speeds being different? I'd think that could be abusive on the mecanum wheels- having them running at a different speed than the traction ones. Any jitterring or efficiency losses?
19-04-2014 19:43
zinthorne
Re: pic: our octanem drive
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Originally Posted by Toa Circuit
Any issues with wheel speeds being different? I'd think that could be abusive on the mecanum wheels- having them running at a different speed than the traction ones. Any jitterring or efficiency losses?
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19-04-2014 20:12
Electronica1
Re: pic: our octanem drive
Are you still able to use the different wheels as 2 different speeds, or is it only one speed (with a normal octocanum, you have smaller traction wheels so it acts as a shifter).
19-04-2014 20:13
Alpha Beta
Re: pic: our octanem drive
We actually had a design similar to this in our initial brain storming session. We called it sextacanum, borrowing from the Latin prefixes. It will be great for the students who proposed this idea to see it in action. We'll have to check out some of your match videos from the PNW.
19-04-2014 20:42
Brandon Zalinsky
Re: pic: our octanem drive
We have pretty much the exact same system on our machine, with the same mecanum wheels. There are only a few differences. First, we have a 6:1 reduction to the traction wheel. Second, the auxiliary wheels are tractioned with Velcro (works incredibly well). To address this-
| Any issues with wheel speeds being different? I'd think that could be abusive on the mecanum wheels- having them running at a different speed than the traction ones. Any jitterring or efficiency losses? |
19-04-2014 21:54
zinthorne
Re: pic: our octanem drive
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Originally Posted by Brandon Zalinsky
We have pretty much the exact same system on our machine, with the same mecanum wheels. There are only a few differences. First, we have a 6:1 reduction to the traction wheel. Second, the auxiliary wheels are tractioned with Velcro (works incredibly well). To address this-
When we actuate the "drop drive", as we call it, down, it tips the bot forward so that we have the two traction wheels and the two mecanums not connected to them contacting the floor. There is then a function in code that drops the speed of the mecanum wheels to 1/6 of their normal speed to make sure that the mecanums and velcro wheels run at the same speed. |
This video has some pushing, and also a great upset win in finals.
https://www.youtube.com/watch?v=WbHHUtCGc1c
This link shows the shifting very well, and the pushing ability. You can see the front end lift up about an inch or two whenever I shift. You can also see how fast it is too.
19-04-2014 21:56
zinthorne
Re: pic: our octanem drive
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Originally Posted by zinthorne
We used transmissions which geared it down to 8:1 and then the extra big traction wheels with the 44 tooth sprocket helped give more power too. Same as in your design, our traction wheels lifted up the back mecanems about a half an inch.
This video has some pushing, and also a great upset win in finals. https://www.youtube.com/watch?v=WbHHUtCGc1c This link shows the shifting very well, and the pushing ability. You can see the front end lift up about an inch or two whenever I shift. You can also see how fast it is too. |
https://www.youtube.com/watch?v=m93XfLe4fj0
20-04-2014 00:31
tStano
Re: pic: our octanem drive
Can you strafe with 6 mecanums? How? The physics aren't working in my mind.
20-04-2014 00:48
EricH
Re: pic: our octanem drive
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Originally Posted by tStano
Can you strafe with 6 mecanums? How? The physics aren't working in my mind.
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Now, I think a 6-mecanum drivetrain could work, provided that the center mecanums were matched to opposite corners--that is, the FL and the RR mecanum wheels are matched to the CL and CR mecanums, and are oriented the same way, either via chain or via programming, or some similar setup.
20-04-2014 01:02
tStano
Re: pic: our octanem drive
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Originally Posted by EricH
It looks like it's a mecanum drive with drop-down traction wheels, rather than a 6-mecanum drivetrain.
Now, I think a 6-mecanum drivetrain could work, provided that the center mecanums were matched to opposite corners--that is, the FL and the RR mecanum wheels are matched to the CL and CR mecanums, and are oriented the same way, either via chain or via programming, or some similar setup. |
And I think you're right, but I think it'd be a mess to get the powers ratios right, because you've got 2 wheels on the ground fighting one. The weight balance would have to be super weird, or there would need to be a lot of math with traction forces, power draw, motor controller and motor curves, and stuff so you could manipulate power ratios so the forward components cancel when you strafe(and the sideways components do when you don't).
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