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Unread 06-07-2018, 03:20 PM
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pic: Off-season Caster Swerve Drive

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Unread 06-07-2018, 03:21 PM
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Re: pic: Off-season Caster Swerve Drive

Is there a reason to use the caster design over a normal swerve?
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Unread 06-07-2018, 03:37 PM
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Re: pic: Off-season Caster Swerve Drive

16 slots from the PDP.....

I'm not even going to try to convince anyone why castered swerve is an oxymoron and a bad idea, it just is..... sorry.
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Unread 06-07-2018, 04:09 PM
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Re: pic: Off-season Caster Swerve Drive

Quote:
Originally Posted by Mark Wasserman View Post
16 slots from the PDP.....

I'm not even going to try to convince anyone why castered swerve is an oxymoron and a bad idea, it just is..... sorry.
I mean, there are interesting things to think about...

https://www.chiefdelphi.com/forums/s...3&postcount=31
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Unread 06-07-2018, 04:15 PM
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Re: pic: Off-season Caster Swerve Drive

Quote:
Originally Posted by Mark Wasserman View Post
16 slots from the PDP.....

I'm not even going to try to convince anyone why <snip> swerve is an oxymoron and a bad idea, it just is..... sorry.
FTFY.

This seems like an overkill type of design for a promotional robot, not an FRC legal robot. You can do whatever you want in that case; more power = more fun! OP never even mentioned how many wheels they plan on using either, it might only be 3. Or 2.
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Unread 06-07-2018, 04:24 PM
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Re: pic: Off-season Caster Swerve Drive

Quote:
Originally Posted by s_forbes View Post
FTFY.

This seems like an overkill type of design for a promotional robot, not an FRC legal robot. You can do whatever you want in that case; more power = more fun! OP never even mentioned how many wheels they plan on using either, it might only be 3. Or 2.
Don't know to much about the specifics but there are 3 wheels and I believe a triangular drive train.
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Unread 06-07-2018, 04:43 PM
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Re: pic: Off-season Caster Swerve Drive

Quote:
Originally Posted by Mark Wasserman View Post
16 slots from the PDP.....

I'm not even going to try to convince anyone why castered swerve is an oxymoron and a bad idea, it just is..... sorry.
Then why post?

Last I checked, no conclusion was reached in any of the CD castor swerve threads regarding the effectiveness of a castor swerve in an FRC context. Judging by your post history, you've not participated in any of those discussions, so you've either not read them, or decided that your opinions were already well stated by others.

In both cases, you really do need to explain why you think a castor swerve is a bad idea if you want to be taken seriously, and you most certainly should explain why you think it's an oxymoron. (which I would reckon is only possible if one misinterprets the operation of a castor swerve or the definition of "oxymoron")
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Unread 06-07-2018, 05:24 PM
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Re: pic: Off-season Caster Swerve Drive

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Originally Posted by AlexanderTheOK View Post
Then why post?

you really do need to explain why you think a castor swerve is a bad idea
As I replied to the most recent caster (not castor, which is vegetable oil) swerve drive posting, the purpose of rake and trail which results in caster is to make a following-wheel more stable while following, going straight.

The purpose of swerve is to be able to turn readily, at will. So making it harder to turn doesn't make sense. To me.

If you can tell me why you want to caster it, I'm listening.
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Unread 06-07-2018, 05:44 PM
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Re: pic: Off-season Caster Swerve Drive

Quote:
Originally Posted by hrench View Post
the purpose of rake and trail which results in caster is to make a following-wheel more stable while following, going straight.

The purpose of swerve is to be able to turn readily, at will. So making it harder to turn doesn't make sense. To me.

If you can tell me why you want to caster it, I'm listening.
The purpose of offsetting a swerve wheel has nothing to do with stability. It is merely a side benefit. There is also no trail in such a module, which is evident by just looking at it, so your reference to rake and trail in this post isn't actually relevant, as that's just not how caster swerves are designed and built.

I won't re-type the entirety of that thread, and I highly encourage that you reread it. Please take the time to understand the design and motivations before casting it away.

TL;DR: The purpose of offsetting the wheel is to allow fine adjustments through the steering of the module.

edit: Also, I hear others are partial to using olive oil for their drives, but once you go castor you never go back.

Last edited by AlexanderTheOK : 06-07-2018 at 05:47 PM. Reason: memes
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Unread 06-07-2018, 06:48 PM
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Re: pic: Off-season Caster Swerve Drive

So yes, it is going to have three wheels. Also, the reason that we have chosen to overpower them so much is we know that the robot is likely to be over 200 pounds and we want it to have decent acceleration. The robot is also going to run on 24 volts instead of the normal 12, most of the standard FRC electronics can run on 24 volts but the motors can't. So we are going to run the motors in parrel, for example, the two mini cims will be run of one Talon SRX and one PDP slot this also allows us to use one slip ring per module. So the drivetrain will only be using 6 PDP slots. The reason we are choosing to do a caster drive is that it hasn't been seriously tested yet, we decided that this is a project that would allow us test casters without much risk.

-Owen Wilks

P.S. This design was never meant to be used in a real competition it is just a fun way to test the concept.
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Unread 06-07-2018, 06:52 PM
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Re: pic: Off-season Caster Swerve Drive

Wow. That looks like a very cool design. Let us know how it works out. I bet you learn alot about engineering swerves from it that you can take forward to competition. Just ignore the naysayers. There seems to be a lot of unnecessary negativity on CD as of late.
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Unread 06-07-2018, 07:59 PM
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Re: pic: Off-season Caster Swerve Drive

Quote:
Originally Posted by owen.wilks.2471 View Post
Nice work Owen. It looks great! One suggestion I have is to add a rib in the middle of the slot for the 775 vents. It shouldn't block airflow, and will improve the motors' mounting rigidity.

Quote:
Originally Posted by Mark Wasserman View Post
16 slots from the PDP.....

I'm not even going to try to convince anyone why castered swerve is an oxymoron and a bad idea, it just is..... sorry.
I'm really curious what your motivations were for making this post. Please enlighten me.

Quote:
Originally Posted by ethanhavens0500 View Post
If you can tell me why you want to caster it, I'm listening.
Owen touched on the motivation for this application, but in a more general sense, an offset wheel would be used on a swerve for the same reason that one would be used on an unpowered caster: So that the structure it's mounted to can move immediately in any direction without skidding the wheel.
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Last edited by Bryce2471 : 06-07-2018 at 08:01 PM.
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Unread 06-07-2018, 09:28 PM
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Re: pic: Off-season Caster Swerve Drive

Cool design!

How did you go about determining the position of the idler pulleys?
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Unread 06-07-2018, 10:02 PM
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Re: pic: Off-season Caster Swerve Drive

Quote:
Originally Posted by tickspe15 View Post
Cool design!

How did you go about determining the position of the idler pulleys?
Iíll offer what I do in Solidworks (it may be different in Inventor, which is what I believe 2471 uses):

Usually on the master sketch for the part, Iíll make a belt layout with the Input and output pulleys fully defined, but with the idler under-defined. Those pulleys are represented as circles with the pitch diameters (you can typically just look these up). Iíd then create a path-length dimension set to the tooth count times the pitch (ex: 80t HTD 5mm -> 400mm length). Iíd then drag around the idler until itís in a position I like, then dimension it into place. When making the plate itself, the idler usually doesnít get a hole but a slot, to make tensioning easier.

Feel free to pm me if you want more info or if I just donít make sense.
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Unread 06-07-2018, 10:14 PM
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Re: pic: Off-season Caster Swerve Drive

Quote:
Originally Posted by owen.wilks.2471 View Post
So yes, it is going to have three wheels. Also, the reason that we have chosen to overpower them so much is we know that the robot is likely to be over 200 pounds and we want it to have decent acceleration. The robot is also going to run on 24 volts instead of the normal 12, most of the standard FRC electronics can run on 24 volts but the motors can't. So we are going to run the motors in parrel, for example, the two mini cims will be run of one Talon SRX and one PDP slot this also allows us to use one slip ring per module. So the drivetrain will only be using 6 PDP slots. The reason we are choosing to do a caster drive is that it hasn't been seriously tested yet, we decided that this is a project that would allow us test casters without much risk.

-Owen Wilks


P.S. This design was never meant to be used in a real competition it is just a fun way to test the concept.

Please verify the maximum input/battery voltage allowed on the current PDP manufactured by CTRE and the previous PDB to ensure that they will function properly in your proposed application.
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