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-   -   2017 Drive Train (http://www.chiefdelphi.com/forums/showthread.php?t=153231)

Koko Ed 09-01-2017 11:04

Re: 2017 Drive Train
 
Quote:

Originally Posted by pfreivald (Post 1627828)
We did straight mecanum for two years, switched to octocanum for a few years, did mecanum again for Recycle Rush. I've never had a student programmer who couldn't fully program a mecanum drive exactly like a 3rd person shooter in at most an afternoon.

There's this myth that mecanum is hard to program. It just isn't. (It's also incredibly easy to build. Just direct-drive four wheels off of appropriate gearboxes, and voila.)

That said, straight-up mecanum will be a mistake this year. The parallels to Ultimate Ascent say defense will be *huge*, and mecanum drives don't do a good job powering through defense.

or the eventual ball pit the field will rapidly become...

Kevin Sevcik 09-01-2017 11:06

Re: 2017 Drive Train
 
Quote:

Originally Posted by pfreivald (Post 1627828)
That said, straight-up mecanum will be a mistake this year. The parallels to Ultimate Ascent say defense will be *huge*, and mecanum drives don't do a good job powering through defense.

Ultimate Ascent is definitely a good game to reference. Shooting, cross-field cycling, hoovering scoring items, and two giant structures clogging everything up. The biggest difference is you can't expand the field by driving under the obstacles. 4 robot pile-ups next to one of the airships are going to be common. Being able to push around the side of that pile is going to be important.

daliberator 09-01-2017 11:10

Re: 2017 Drive Train
 
Based on the current stock Andymark has for Toughbox Micros, I think that a lot of teams are going for mecanum.:yikes:

mypie4050 09-01-2017 11:45

Re: 2017 Drive Train
 
Quote:

Originally Posted by Jay O'Donnell (Post 1627559)
If there was ever a game to not overthink your drivetrain and just build a really simple tank drive, this would probably be it.

This is very good advice. Any robot with a mecanum or omin train will likely be very easy to push around and be highly ineffective at both shooting and gearing (my proposed term for scoring gears).

7keleher 09-01-2017 14:04

Re: 2017 Drive Train
 
We used h-drive in 2015 and got it working great. Mechanum is something we have never done because a) we haven't needed it and b) its more complicated than a tank or h-drive. For this year's game tank drive is probably best. For lining things up, just practice with the tank drive and build some mechanisms in for maneuvering game pieces within the bot.

chandrew 09-01-2017 21:42

Re: 2017 Drive Train
 
Quote:

Originally Posted by s-neff (Post 1627563)
In a pushing match, yes.

I would actually disagree with this. If you have a good gear ratio on a mecanum you can get a decent amount of force. Our team went mecanum in 2014 and we're actually able to push the more basic tank drives around.

messer5740 09-01-2017 21:57

Re: 2017 Drive Train
 
Basic question but couldnt find it anywhere else:
How fast does the andymark KOP chassis go?

slhs 09-01-2017 22:03

Re: 2017 Drive Train
 
1 Attachment(s)
Quote:

Originally Posted by messer5740 (Post 1628305)
Basic question but couldnt find it anywhere else:
How fast does the andymark KOP chassis go?

From user guide:

Jpatterson1710 10-01-2017 00:19

Re: 2017 Drive Train
 
Quote:

Originally Posted by Kevin Sevcik (Post 1627754)
Butterfly drive, especially shifting butterfly drive, is probably only a good idea for teams that already know what it is and aren't cruising CD for suggestions on drivetrain decisions.

Quote:

Originally Posted by Cothron Theiss (Post 1627767)
I don't want this to turn into a mecanum vs tank drive thread or an articulated drive vs tank drive thread, but I think the reasoning behind selecting a simple tank drive is more applicable this year than just about any other. An articulated drive might perform better as a drivetrain than a dropped center tank drive. But is it worth investing 2/3 of your weight allowance and 2/3 of your build season getting a complicated drive system working? Or is it better to build something that is robust and reliable, and spend that time on your subsystems and practicing to improve performance?

I totally agree, I just thought it was a fitting video to add to the conversation. Drivetrain R&D is not for build season.

Tom Line 10-01-2017 00:58

Re: 2017 Drive Train
 
Quote:

Originally Posted by Kevin Sevcik (Post 1627836)
Ultimate Ascent is definitely a good game to reference. Shooting, cross-field cycling, hoovering scoring items, and two giant structures clogging everything up. The biggest difference is you can't expand the field by driving under the obstacles. 4 robot pile-ups next to one of the airships are going to be common. Being able to push around the side of that pile is going to be important.

Not to let the cat out of the bag, but Ultimate ascent is the PERFECT game to benchmark against. Full field cycling ruled that year. Take a look at what the top 15 teams were running.

In fact, Ultimate ascent was easier than this game when it came to driving, because you could put yourself in safe zones when you shot. This year? Prepared to be pushed while putting the gear on or shooting into the goal.

Build a tank drive.

dardeshna 10-01-2017 02:21

Re: 2017 Drive Train
 
On a slightly different note, what motor / gearing / wheel size setup are you all using? Ideal feet per second I would imagine is relatively high. Shifting or no shifting? We are leaning towards 6 cim ~10-12 fps no shifting but I don't have great experience to tell if we got it in the right range or not for this game.

Jay O'Donnell 10-01-2017 03:13

Re: 2017 Drive Train
 
Quote:

Originally Posted by dardeshna (Post 1628405)
On a slightly different note, what motor / gearing / wheel size setup are you all using? Ideal feet per second I would imagine is relatively high. Shifting or no shifting? We are leaning towards 6 cim ~10-12 fps no shifting but I don't have great experience to tell if we got it in the right range or not for this game.

I've heard of plenty of teams thinking about doing exactly this actually. The benefit of that setup is a greater acceleration, so you can travel at that top speed for long straightaways across the field.

Personally I'm not a big shifting guy, I think it takes a very skilled driver to use it effectively.

TheMagicPenguin 10-01-2017 07:07

Re: 2017 Drive Train
 
Here on 1640 we plan to use our swerve drive again (big suprise). This year we are also going to introduce our CVT swerve to the field.

Darkseer54 10-01-2017 08:45

Re: 2017 Drive Train
 
Quote:

Originally Posted by Cothron Theiss (Post 1627767)
I don't want this to turn into a mecanum vs tank drive thread or an articulated drive vs tank drive thread, but I think the reasoning behind selecting a simple tank drive is more applicable this year than just about any other. An articulated drive might perform better as a drivetrain than a dropped center tank drive. But is it worth investing 2/3 of your weight allowance and 2/3 of your build season getting a complicated drive system working? Or is it better to build something that is robust and reliable, and spend that time on your subsystems and practicing to improve performance?

How about 45lbs, with a functioning control system, working pneumatic system, a compressor too big for its own good, a metal tank, and a huge excess of wires and pneumatic tubing? Just because one 8 motor octocanum weighs 90 lbs doesn't mean all of them do.

https://www.youtube.com/watch?v=sf-mNuGsVhQ
Quote:

Originally Posted by Jpatterson1710 (Post 1627694)
Just Sayin.


JediSy 10-01-2017 11:45

Re: 2017 Drive Train
 
I personally think mechanum or Omni with tread-wheel hybrid. That's just an idea though. Problem is the amperage for mechanum.


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