Go to Post We, as mentors, receive our greatest reward when our students become role models and give of their time to others in need. - Al Skierkiewicz [more]
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 Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 12-11-2006, 14:15
Rob2713g's Avatar
Rob2713g Rob2713g is offline
Registered User
FRC #0540 (Screaming Eagles)
 
Join Date: Apr 2006
Rookie Year: 2004
Location: VA
Posts: 143
Rob2713g has a spectacular aura aboutRob2713g has a spectacular aura aboutRob2713g has a spectacular aura about
Swerve/Crab

Hey,
It is too close to season to probably get a swerve drive working, but I wanted to have some more info on it (most likely for next year).
I've looked through CD-media and was wondering if anyone has any CAD designs my team could look at (ideally in Inventor, but I'll take anything)?
Also does anyone have any specific advice? I've found a lot of designs, but have they been successful or did you end up reverting back to your old drive train?
Finally how would you compare mecanum to swerve?
Any help would be greatly appreciated! Thanks!!
  #2   Spotlight this post!  
Unread 12-11-2006, 14:21
Michael Hill's Avatar
Michael Hill Michael Hill is offline
Registered User
FRC #3138 (Innovators Robotics)
Team Role: Mentor
 
Join Date: Jul 2004
Rookie Year: 2003
Location: Dayton, OH
Posts: 1,580
Michael Hill has a reputation beyond reputeMichael Hill has a reputation beyond reputeMichael Hill has a reputation beyond reputeMichael Hill has a reputation beyond reputeMichael Hill has a reputation beyond reputeMichael Hill has a reputation beyond reputeMichael Hill has a reputation beyond reputeMichael Hill has a reputation beyond reputeMichael Hill has a reputation beyond reputeMichael Hill has a reputation beyond reputeMichael Hill has a reputation beyond repute
Re: Swerve/Crab

Mecanum is rather iffy. First, you'll never get the full power of the motors because it's vector based. Also, it's somewhat difficult to keep your robot from turning in circles when going sideways. I'm guessing this is due to not all motors having the exact same specs as all the other motors. That's another thing with mecanum, you have to have a motor per wheel with no chain. When we tried out a mecanum drive base, there were some issues with use going around in circles.
  #3   Spotlight this post!  
Unread 12-11-2006, 15:43
Lil' Lavery Lil' Lavery is offline
TSIMFD
AKA: Sean Lavery
FRC #1712 (DAWGMA)
Team Role: Mentor
 
Join Date: Nov 2003
Rookie Year: 2003
Location: Philadelphia, PA
Posts: 6,643
Lil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond reputeLil' Lavery has a reputation beyond repute
Send a message via AIM to Lil' Lavery
Re: Swerve/Crab

Mecanum and swerve are two entirely different animals. Mecanum drives are vector based, and result in less efficiency (and therefor less power from your motors). But mecanums can change direction almost instantly.
Swerves get roughly the same power output from their motors as a differential (Scrub) steered robot would, with the exception that their "steering" motor(s) give no output power to the drivetrain. Swerves take more motors than any other drivetrains and are often the heaviest wheeled drivetrain. They cannot change direction instantly, as it takes time for their motors to re-position.
__________________
Being correct doesn't mean you don't have to explain yourself.
  #4   Spotlight this post!  
Unread 12-11-2006, 17:33
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 10,798
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Swerve/Crab

Crab steering (this is the term used for swerve since it emulates the way a crab walks.) is not needed for every game. For this reason, we do not decide which drive train we will use until after the game has been analyzed. This year's game did not require crab steering. When maneuverability is an absolute must or when the robot is required to move sideways to pick up or retrieve then crab is a possibility. The design of the drive modules will determine the weight and individual transmissions can double the weight if similarly sized gears as tank designs are used. Since each tranny carries less load, the components can be lighter.
Of prime importance is the ability to control the steering. Therefore a good feedback system and software are needed. The operator control is another factor that needs thought to make driving easy. Designs can have other problems that vary with the design. How will you get wiring down into the module, will the module contain the motor or will all the drive components be outside the rotating device. What is the game going to require as to the base dimension and what is needed for retrieval of game objects. You may find that a design that requires 8 or 10 in. sq. will not allow space between the modules for other robot components. Finally, How do you get to Carnegie Hall? Practice, Practice, Practice. Even the best crab drive system won't get you anywhere if your drivers can't control the robot well enough to play the game.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Storming the Tower since 1996.
  #5   Spotlight this post!  
Unread 12-11-2006, 21:52
Joe_Widen's Avatar
Joe_Widen Joe_Widen is offline
Registered User
FRC #1675 (The Ultimate Protection Squad)
Team Role: Alumni
 
Join Date: Jan 2006
Rookie Year: 2005
Location: Milwaukee
Posts: 215
Joe_Widen has much to be proud ofJoe_Widen has much to be proud ofJoe_Widen has much to be proud ofJoe_Widen has much to be proud ofJoe_Widen has much to be proud ofJoe_Widen has much to be proud ofJoe_Widen has much to be proud ofJoe_Widen has much to be proud of
Re: Swerve/Crab

I have a few cad drawings of a crab drive (partially inspired by Hammond, Wildstang, Hot Bot, and Rage.) '

http://www.chiefdelphi.com/media/photos/25248
http://www.chiefdelphi.com/media/photos/25250
http://www.chiefdelphi.com/media/photos/25228
http://www.chiefdelphi.com/media/photos/25227
__________________
Finally in college =]


2009 Midwest Regional Champions - Thanks 111 and 1625
  #6   Spotlight this post!  
Unread 12-11-2006, 22:05
Greg Needel's Avatar Unsung FIRST Hero
Greg Needel Greg Needel is offline
REVving up for a new season
FRC #2848 (All-sparks)
Team Role: Engineer
 
Join Date: Jan 2002
Rookie Year: 2002
Location: Dallas, TX
Posts: 3,110
Greg Needel has a reputation beyond reputeGreg Needel has a reputation beyond reputeGreg Needel has a reputation beyond reputeGreg Needel has a reputation beyond reputeGreg Needel has a reputation beyond reputeGreg Needel has a reputation beyond reputeGreg Needel has a reputation beyond reputeGreg Needel has a reputation beyond reputeGreg Needel has a reputation beyond reputeGreg Needel has a reputation beyond reputeGreg Needel has a reputation beyond repute
Re: Swerve/Crab

Quote:
Originally Posted by Joe_Widen

If you wanted to make them available for download I will host the files for you. Email me gneedel(at)gmail(dot)com
__________________
Greg Needel│www.robogreg.com
Co-founder REV Robotics LLC www.REVrobotics.com
2014 FRC World Champions with 254, 469, & 74
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

Similar Threads
Thread Thread Starter Forum Replies Last Post
pic: Swerve! =Martin=Taylor= Extra Discussion 15 07-07-2006 01:58
Crab/Swerve/Synchro Pics Joe_Widen Technical Discussion 6 15-04-2006 20:54
Swerve/crab drive and tank turning activemx Technical Discussion 9 23-02-2004 18:26
pic: Swerve^2 Prototype CD47-Bot Robot Showcase 24 23-01-2004 12:11
Swerve Drive Jeff Waegelin Technical Discussion 14 17-09-2001 08:06


All times are GMT -5. The time now is 07:14.

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