Nothing in the KOP can prepare me for you.
Home
Go Back   Chief Delphi > Technical > Technical Discussion
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
 
Thread Tools Rating: Thread Rating: 6 votes, 5.00 average. Display Modes
  #1   Spotlight this post!  
Unread 29-04-2014, 01:15
asid61's Avatar
asid61 asid61 is offline
Registered User
AKA: Anand Rajamani
FRC #1072 (Harker Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Cupertino, CA
Posts: 2,234
asid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond repute
Butterfly/ octocanum drives

So a butterfly/ octocanum drive is where you switch between mecanum and traction wheels, right?
I was wondering what the typical weight and complexity of these systems was. This would be weight per module or, preferably, weight of bellypan + drive base + modules. I have only found one weight listing for an octocanum module, and I think many teams keep the mass under 11lbs.
How long does this take to design? Does this need a particular CNC special part or can it be fabricated with a waterjet/ sheet metal shop?
Any information on these drives would be useful, as I'm looking into different drives for a summer project.

Last edited by asid61 : 29-04-2014 at 01:20.
  #2   Spotlight this post!  
Unread 29-04-2014, 01:29
BJC's Avatar
BJC BJC is offline
Simplicity is Complicated!
AKA: Bryan Culver
FRC #0033 (The Killer Bees)
Team Role: Alumni
 
Join Date: Jan 2010
Rookie Year: 2009
Location: Kettering/Greenville
Posts: 708
BJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond repute
Re: Butterfly drives

Quote:
Originally Posted by asid61 View Post
So a butterfly drive is where you switch between mecanum and traction wheels, correct?
I was wondering what the typical weight and complexity of these systems was. This would be weight per module or, preferably, weight of bellypan + drive base + modules.
How long does this take to design? Does this need a particular special part or can it be fabricated with a waterjet/ sheet metal guy?
Any information on these drives would be useful, as I'm looking into different drives for a summer project.
Assigning names to a "design" is so limiting. That said a butterfly drive conventionally switches between 4 omni wheels and 4 traction wheels.

I would encourage you to sit down with your team and figure out a list of objectives you would like your summer project to fulfill. Once you've done this I would encourage you to use the chiefdelphi search function to read up on butterfly drives from older threads. Once you understand your design objectives, have an idea of where a butterfly type drive falls on that, and seen a number of designs other teams have already made you can properly assess if you should try to design and build one or if your time would be better spent working on something else. When done properly off season projects can be an extremely valuable resource both in terms of populating your team's design shelf and teaching students. The most important thing is to have a full understanding of why you are building what you are building and how you are trying to improve upon what you have done in the past, have seen others do in competition, or online.

Cheers, Bryan
__________________
robot robot robot? Robot. Robot? Robot!
-----------------Team 33------------------

Last edited by BJC : 29-04-2014 at 01:41.
  #3   Spotlight this post!  
Unread 29-04-2014, 01:40
asid61's Avatar
asid61 asid61 is offline
Registered User
AKA: Anand Rajamani
FRC #1072 (Harker Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Cupertino, CA
Posts: 2,234
asid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond repute
Re: Butterfly drives

Quote:
Originally Posted by BJC View Post
Assigning names to a "design" is so limiting. That said a butterfly drive conventionally switches between 4 omni wheels and 4 traction wheels.

I would encourage you to sit down with your team and figure out a list of objectives you would like your summer project to fulfill. Once you've done this I would encourage you to use the chiefdelphi search function to read up on butterfly drives from older threads. Once you understand your design objectives, have an idea of where a butterfly type drive falls on that, and seen a number of designs other teams have already made you can properly assess if you should try to design and build one or if your time would be better spent working on something else. When done properly off season projects can be an extremely valuable resource both in terms of populating your team's design shelf and teaching students.

Cheers, Bryan
Actually, right now it's just me looking at drive train ideas; other people have AP tests to study for right now and just a lot of schoolwork in general. I want to have a list of detailed CAD designs to show the team later once we start thinking about summer projects, so that we can make an educated decision about what we want to try.
I've been cadding only swerve drives and shifting gearboxes up to this point, but I was wondering what I should aim for in terms of weight and size if I CAD a butterfly later.
I want to stick with swerve personally, but the problem is that the programming is very difficult. With a butterfly drive, there is already a lot of programming released, not to mention the programming overall is easier.
  #4   Spotlight this post!  
Unread 29-04-2014, 07:43
tim-tim's Avatar
tim-tim tim-tim is offline
Simplicity by Design...
AKA: Tim Miedzinski
FRC #0836 (The RoboBees)
Team Role: Mentor
 
Join Date: Feb 2007
Rookie Year: 2004
Location: Hollywood
Posts: 605
tim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond repute
Re: Butterfly/ octocanum drives

Quote:
Originally Posted by asid61 View Post
So a butterfly/ octocanum drive is where you switch between mecanum and traction wheels, right?
I was wondering what the typical weight and complexity of these systems was. This would be weight per module or, preferably, weight of bellypan + drive base + modules. I have only found one weight listing for an octocanum module, and I think many teams keep the mass under 11lbs.
How long does this take to design? Does this need a particular CNC special part or can it be fabricated with a waterjet/ sheet metal shop?
Any information on these drives would be useful, as I'm looking into different drives for a summer project.
As BJC said, butterfly is [typically] switching between omni and traction wheels; while octocanum is [typically] switching between mecanum and traction wheels.

The main difference between the two are choosing what wheel is opposite of the traction wheel on the pod. While I have not built one, the drives should be slightly heavier than a conventional drive. Majority of these setups use a single gear reduction to the first wheel and then another reduction via chain or belt to the second wheel. This makes up for the weight "missing" from gearboxes.

There are some good examples out there on how they have been constructed in the past. 148 made this type of setup popular in their 2010 release video and their CAD files can be seen on FRC designs and you can see another iteration in their 2011 robot. Another great example is 3847's robot from this year. It was documented fairly well in their build blog. Both of these teams are more than willing to help answer further questions, but these should give you a good starting point. There are plenty of other robots that use these drive types that I didn't mention, these were two I could get my hands on quickly.
__________________
The RoboBees

Tim's Shortcuts Anderson Powerpoles and Crimper, Star/Tube Nuts
  #5   Spotlight this post!  
Unread 29-04-2014, 15:16
ErvinI ErvinI is offline
Registered User
AKA: Ervin Ibadula
FRC #0865 (Warp7)
Team Role: Mentor
 
Join Date: Feb 2013
Rookie Year: 2011
Location: Kincardine, ON
Posts: 144
ErvinI is just really niceErvinI is just really niceErvinI is just really niceErvinI is just really niceErvinI is just really nice
Re: Butterfly/ octocanum drives

Quote:
Originally Posted by tim-tim View Post
There are some good examples out there on how they have been constructed in the past. 148 made this type of setup popular in their 2010 release video and their CAD files can be seen on FRC designs and you can see another iteration in their 2011 robot.
I don't remember the terminology too well, but wasn't the 2010 robot a Nonadrive, since it had a ninth wheel that was actuated down to allow for holonomic drive? Their 2011 robot was iirc their first true butterfly after they realized that the ninth wheel wasn't required for basic strafing.
__________________
Currently a student at the University of Toronto - Mechanical Engineering
FRC 781 alumni
  #6   Spotlight this post!  
Unread 29-04-2014, 16:28
Unsung FIRST Hero
JVN JVN is offline
@JohnVNeun
AKA: John Vielkind-Neun
FRC #0148 (Robowranglers)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 2000
Location: Greenville, Tx
Posts: 3,159
JVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond repute
Re: Butterfly/ octocanum drives

Quote:
Originally Posted by ErvinI View Post
I don't remember the terminology too well, but wasn't the 2010 robot a Nonadrive, since it had a ninth wheel that was actuated down to allow for holonomic drive? Their 2011 robot was iirc their first true butterfly after they realized that the ninth wheel wasn't required for basic strafing.
I talked about the history of 148's articulating drives, and the evolution of the "Tex-Coast Drive" here:
http://www.chiefdelphi.com/forums/sh...9&postcount=15
__________________
In the interest of full disclosure: I work for VEX Robotics a subsidiary of Innovation First International (IFI) Crown Supplier & Proud Supporter of FIRST
  #7   Spotlight this post!  
Unread 29-04-2014, 16:41
tim-tim's Avatar
tim-tim tim-tim is offline
Simplicity by Design...
AKA: Tim Miedzinski
FRC #0836 (The RoboBees)
Team Role: Mentor
 
Join Date: Feb 2007
Rookie Year: 2004
Location: Hollywood
Posts: 605
tim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond reputetim-tim has a reputation beyond repute
Re: Butterfly/ octocanum drives

Quote:
Originally Posted by ErvinI View Post
I don't remember the terminology too well, but wasn't the 2010 robot a Nonadrive, since it had a ninth wheel that was actuated down to allow for holonomic drive? Their 2011 robot was iirc their first true butterfly after they realized that the ninth wheel wasn't required for basic strafing.
You are correct in the fact that in 2010 it was nonadrive; however if you ignore the 9th wheel (omni in the center) it is an iteration of the drives being discussed.

I think terminology, albeit important, can sometimes limit creativity.
__________________
The RoboBees

Tim's Shortcuts Anderson Powerpoles and Crimper, Star/Tube Nuts
  #8   Spotlight this post!  
Unread 29-04-2014, 19:25
asid61's Avatar
asid61 asid61 is offline
Registered User
AKA: Anand Rajamani
FRC #1072 (Harker Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Cupertino, CA
Posts: 2,234
asid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond repute
Re: Butterfly/ octocanum drives

Thanks for all the replies. I especially enjoyed the Grasshopper drive (I saw that a couple weeks ago) because it seemed very lightweight @ 30lbs. Also, it didn't look like it would take too much effort for even an inexperienced team due to the fact that the amount of lift on the wheels could vary quite a bit.

So it looks like these modules are a little on the heavy side at around 8-12 lbs, maybe 6 or 7 optimized. It looks like these could be pretty useful to us next year in leiu of a heavy swerve. Thank you so much for all the input!
  #9   Spotlight this post!  
Unread 29-04-2014, 19:56
Madison's Avatar
Madison Madison is offline
Dancing through life...
FRC #0488 (Xbot)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1999
Location: Seattle, WA
Posts: 5,246
Madison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond repute
Re: Butterfly/ octocanum drives

Our octocanum modules are 5.75 lbs. each. The pneumatic cylinders driving each pod were mounted to the frame and I don't have the weight of each of those handy. We used four, but you could as easily use 1, 2 or 4 as your frame allowed.

Our first octocanum implementation in 2011, itself the first used in FRC, was made entirely in-house and with no advanced machining techniques. It was designed and built in just a few weeks and while heavy, it was very reliable and effective.

Our 2014 implementation is made with sheet metal and that helped us to realize a lot of weight savings. We relied on our experience from 2011 to design and code the drive quickly.
__________________
--Madison--

...down at the Ozdust!

Like a grand and miraculous spaceship, our planet has sailed through the universe of time. And for a brief moment, we have been among its many passengers.
  #10   Spotlight this post!  
Unread 29-04-2014, 20:07
asid61's Avatar
asid61 asid61 is offline
Registered User
AKA: Anand Rajamani
FRC #1072 (Harker Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Cupertino, CA
Posts: 2,234
asid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond reputeasid61 has a reputation beyond repute
Re: Butterfly/ octocanum drives

Quote:
Originally Posted by Madison View Post
Our octocanum modules are 5.75 lbs. each. The pneumatic cylinders driving each pod were mounted to the frame and I don't have the weight of each of those handy. We used four, but you could as easily use 1, 2 or 4 as your frame allowed.

Our first octocanum implementation in 2011, itself the first used in FRC, was made entirely in-house and with no advanced machining techniques. It was designed and built in just a few weeks and while heavy, it was very reliable and effective.

Our 2014 implementation is made with sheet metal and that helped us to realize a lot of weight savings. We relied on our experience from 2011 to design and code the drive quickly.
Wow, that's super light! Even with cylinders, I can't see that popping up to more than 7lbs.
We have a sheet metal guy, but CNC is up in the air right now (our local college can only machine on weekends and they like the manuals).
  #11   Spotlight this post!  
Unread 29-04-2014, 21:52
azcalg's Avatar
azcalg azcalg is offline
Registered User
FRC #1212 (Sentinels)
Team Role: Engineer
 
Join Date: Jan 2014
Rookie Year: 2012
Location: Chandler, AZ
Posts: 36
azcalg is a jewel in the roughazcalg is a jewel in the roughazcalg is a jewel in the roughazcalg is a jewel in the rough
Re: Butterfly/ octocanum drives

I've been looking at octocanum drive trains as well and come up with several designs so far. I found this thread of 2583's design very useful, and there's information about calculating whether or not you get enough force out of your piston to lift the robot. Also, it's definitely possible to make a working design without CNC or anything heavy duty, but you'll probably want to use belts or chains if that's the case, so you can tension out any discrepancies in hole spacing. We've actually already started on a very crude prototype with chains, but we plan on upgrading to gears in the final design.
As for how long it takes to design, I'd say not very long at all, so long as you have a relatively clear picture of how the finished product will look like. And given the many existing designs you can access, that shouldn't be too hard.
  #12   Spotlight this post!  
Unread 29-04-2014, 22:39
cadandcookies's Avatar
cadandcookies cadandcookies is offline
Director of Programs, GOFIRST
AKA: Nick Aarestad
FTC #9205 (The Iron Maidens)
Team Role: College Student
 
Join Date: Jan 2012
Rookie Year: 2009
Location: Minnesnowta
Posts: 1,565
cadandcookies has a reputation beyond reputecadandcookies has a reputation beyond reputecadandcookies has a reputation beyond reputecadandcookies has a reputation beyond reputecadandcookies has a reputation beyond reputecadandcookies has a reputation beyond reputecadandcookies has a reputation beyond reputecadandcookies has a reputation beyond reputecadandcookies has a reputation beyond reputecadandcookies has a reputation beyond reputecadandcookies has a reputation beyond repute
Re: Butterfly/ octocanum drives

If you're talking about octocanum without CNC, I believe 525 ran a handmade octocanum setup for a few years. Might be worth checking out their CAD files (among other reasons to check out their files-- they have the most detailed modeling I've ever seen from a team).
__________________

Never assume the motives of others are, to them, less noble than yours are to you. - John Perry Barlow
tumblr | twitter
'Snow Problem CAD Files: 2015 2016
MN FTC Field Manager, FTA, CSA, Emcee
FLL Maybe NXT Year (09-10) -> FRC 2220 (11-14) -> FTC 9205(14-?)/FRC 2667 (15-16)
VEXU UMN (2015-??)
Volunteer since 2011
2013 RCA Winner (North Star Regional) (2220)
2016 Connect Award Winner (North Super Regional and World Championship) (9205)
  #13   Spotlight this post!  
Unread 30-04-2014, 14:30
philso philso is offline
Mentor
FRC #2587
 
Join Date: Jan 2011
Rookie Year: 2011
Location: Houston, Tx
Posts: 941
philso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond repute
Re: Butterfly/ octocanum drives

We built an octanum system without regular access to CNC equipment. I do not recommend doing that unless you have an experienced machinist guiding the manufacturing effort and making sure the parts are being made accurately and consistently.

There are similarities and differences between our modules and the modules that 148 used. Both our modules used one of the axles in each module as the "pivot axle" for the module to move up and down.

In our modules, the pivot axle was a live axle making it necessary to install bearings in the chassis to hold the axle. We also had bearings on the side plates of the module.

In 148's module, the pivot axle was a dead axle so the wheel on that axle had bearings in it. Their module side plates had bearing just like ours. Their pivot axle was screwed into the chassis with a 1/4-20 bolt at each end.

I think our modules had the same number of major parts as 148's modules so the complexity was similar. The big difference was manufacturability and serviceability. Our modules could only be partially assembled before installation. We had to insert the pivot axle, it's bearings, the wheel and all the spacers while it was in the chassis. It took a lot of time and effort to make any changes to the module. 148's could be fully assembled on the workbench and installed into the chassis by screwing in the two 1/4-20 bolts.
  #14   Spotlight this post!  
Unread 30-04-2014, 18:53
Aren_Hill's Avatar
Aren_Hill Aren_Hill is offline
Build Nifty Things
no team
Team Role: Mentor
 
Join Date: Feb 2005
Rookie Year: 2005
Location: Menlo Park CA
Posts: 1,220
Aren_Hill has a reputation beyond reputeAren_Hill has a reputation beyond reputeAren_Hill has a reputation beyond reputeAren_Hill has a reputation beyond reputeAren_Hill has a reputation beyond reputeAren_Hill has a reputation beyond reputeAren_Hill has a reputation beyond reputeAren_Hill has a reputation beyond reputeAren_Hill has a reputation beyond reputeAren_Hill has a reputation beyond reputeAren_Hill has a reputation beyond repute
Re: Butterfly/ octocanum drives

Quote:
Originally Posted by philso View Post
We built an octanum system without regular access to CNC equipment. I do not recommend doing that unless you have an experienced machinist guiding the manufacturing effort and making sure the parts are being made accurately and consistently.

There are similarities and differences between our modules and the modules that 148 used. Both our modules used one of the axles in each module as the "pivot axle" for the module to move up and down.

In our modules, the pivot axle was a live axle making it necessary to install bearings in the chassis to hold the axle. We also had bearings on the side plates of the module.

In 148's module, the pivot axle was a dead axle so the wheel on that axle had bearings in it. Their module side plates had bearing just like ours. Their pivot axle was screwed into the chassis with a 1/4-20 bolt at each end.

I think our modules had the same number of major parts as 148's modules so the complexity was similar. The big difference was manufacturability and serviceability. Our modules could only be partially assembled before installation. We had to insert the pivot axle, it's bearings, the wheel and all the spacers while it was in the chassis. It took a lot of time and effort to make any changes to the module. 148's could be fully assembled on the workbench and installed into the chassis by screwing in the two 1/4-20 bolts.
The 148 module was actually just one long 1/4-20 bolt through a piece of VEXpro tube axle.
__________________
A guy who likes robots.
1625->3928->148->1296->971 oh dear
  #15   Spotlight this post!  
Unread 29-04-2014, 11:58
RobotDoktor's Avatar
RobotDoktor RobotDoktor is offline
Cat Herder
FRC #4265 (Secret City)
Team Role: CAD
 
Join Date: Dec 2013
Rookie Year: 2013
Location: United States
Posts: 68
RobotDoktor is just really niceRobotDoktor is just really niceRobotDoktor is just really niceRobotDoktor is just really niceRobotDoktor is just really nice
If you design an octocanum or butterfly, be ready to spend at least two or three months to go from concept to working prototype. If you use bent sheet metal for your modules you need a water jet, if you use 1/4" aluminum plates, you need a good CNC. Do know that they can be much heavier than other drivetrains depending on their features, so they aren't suitable for some games.
__________________
Full disclosure: I am not a robot, a doctor, or a German.
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 20:56.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi