Go to Post That seems like a pretty cool idea! Who'da thunk o' dat?! :rolleyes: - dlavery [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

 
Reply
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 07-02-2017, 21:30
messer5740's Avatar
messer5740 messer5740 is offline
Registered User
FRC #5740 (Trojanators)
Team Role: Driver
 
Join Date: Jan 2016
Rookie Year: 2015
Location: Pittsburgh
Posts: 142
messer5740 is an unknown quantity at this point
H-Drive Strafing issues

Hey CD
So we are experiencing traction trouble with our H-Drive chassis. When we attempt to strafe, sometimes the wheel just turns and doesn't catch on the ground. We were doing it on polished cement, so that may be an issue, but what to do you all think, what should we do?
__________________
A good driver is always better than a good robot.

2015: Winner of the Rookie Inspiration Award
2016: 8th seed alliance captain at Greater Pittsburgh Regional and 6th seed alliance captain at the Buckeye Regional
Thanks to all our alliance members!
Reply With Quote
  #2   Spotlight this post!  
Unread 07-02-2017, 21:35
Hitchhiker 42's Avatar
Hitchhiker 42 Hitchhiker 42 is offline
Roboter
AKA: Mark Lavrentyev
FRC #4557 (FullMetal Falcons)
Team Role: Programmer
 
Join Date: Oct 2015
Rookie Year: 2015
Location: Cromwell, CT
Posts: 534
Hitchhiker 42 has a reputation beyond reputeHitchhiker 42 has a reputation beyond reputeHitchhiker 42 has a reputation beyond reputeHitchhiker 42 has a reputation beyond reputeHitchhiker 42 has a reputation beyond reputeHitchhiker 42 has a reputation beyond reputeHitchhiker 42 has a reputation beyond reputeHitchhiker 42 has a reputation beyond reputeHitchhiker 42 has a reputation beyond reputeHitchhiker 42 has a reputation beyond reputeHitchhiker 42 has a reputation beyond repute
Re: H-Drive Strafing issues

When we did this in 2015, we found that on carpet, the robot sinks significantly into the carpet for the wheel to catch. You should probably try this out on carpet and see if this is the case. If it is, great! If it still doesn't catch, you may need to lower your center wheel.
__________________



2016 - NE District Championship Entrepreneurship Award
2016 - Hartford District Industrial Design Award
2016 - Waterbury District Engineering Inspiration Award
Reply With Quote
  #3   Spotlight this post!  
Unread 07-02-2017, 21:38
Southpaw's Avatar
Southpaw Southpaw is offline
Registered User
AKA: Spencer Robinson
FRC #3184 (Blaze Robotics)
Team Role: Mechanical
 
Join Date: Jan 2017
Rookie Year: 2014
Location: Burnsville MN
Posts: 11
Southpaw is on a distinguished road
Re: H-Drive Strafing issues

Carpet will most certainly help, what wheel is your strafing drive?
Reply With Quote
  #4   Spotlight this post!  
Unread 07-02-2017, 21:40
Cothron Theiss's Avatar
Cothron Theiss Cothron Theiss is online now
Registered Muser
FRC #4462 (Full Metal Jackets)
Team Role: College Student
 
Join Date: Feb 2016
Rookie Year: 2013
Location: Kingston, Tennessee
Posts: 601
Cothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond reputeCothron Theiss has a reputation beyond repute
Re: H-Drive Strafing issues

Is the strafing wheel at a set position? Is there any way you can increase the amount of normal force on that middle wheel? Carpet will almost certainly help. But it probably won't fix the problem.
__________________
"It's taking longer than expected, which was to be expected."
Reply With Quote
  #5   Spotlight this post!  
Unread 07-02-2017, 22:58
messer5740's Avatar
messer5740 messer5740 is offline
Registered User
FRC #5740 (Trojanators)
Team Role: Driver
 
Join Date: Jan 2016
Rookie Year: 2015
Location: Pittsburgh
Posts: 142
messer5740 is an unknown quantity at this point
Re: H-Drive Strafing issues

The center wheel has no applied force on it, but we do have the majority of our heavy weight items (battery, etc.) toward the center wheel. It is just an Omni wheel with rollers. We should be taking it up to the practice field soon
__________________
A good driver is always better than a good robot.

2015: Winner of the Rookie Inspiration Award
2016: 8th seed alliance captain at Greater Pittsburgh Regional and 6th seed alliance captain at the Buckeye Regional
Thanks to all our alliance members!
Reply With Quote
  #6   Spotlight this post!  
Unread 08-02-2017, 06:31
Joseph Smith's Avatar
Joseph Smith Joseph Smith is offline
Persistence alone is omnipotent.
FRC #3539 (Byting Bulldogs)
Team Role: Engineer
 
Join Date: Apr 2011
Rookie Year: 2011
Location: Romeo
Posts: 194
Joseph Smith has a brilliant futureJoseph Smith has a brilliant futureJoseph Smith has a brilliant futureJoseph Smith has a brilliant futureJoseph Smith has a brilliant futureJoseph Smith has a brilliant futureJoseph Smith has a brilliant futureJoseph Smith has a brilliant futureJoseph Smith has a brilliant futureJoseph Smith has a brilliant futureJoseph Smith has a brilliant future
Re: H-Drive Strafing issues

In 2015 our strafe wheel was in a spring powered suspension setup to keep it in contact with the ground. I don't know what your setup looks like, but it's very difficult to keep weight on a fixed center wheel without lifting up other wheels. One of the best methods I've seen is what 148 did in 2014 with their "rocker" module. Perhaps someone from their team can elaborate on it further.
Attached Thumbnails
Click image for larger version

Name:	16310840838_952591609b_k.jpg
Views:	257
Size:	939.8 KB
ID:	21741  
__________________
Design/fab team 2011-2013
Design/fab mentor 2014--
There are three types of people in the world:
1. Those who make things happen
2. Those who watch things happen
3. Those who wonder what happened.


Last edited by Joseph Smith : 08-02-2017 at 06:46.
Reply With Quote
  #7   Spotlight this post!  
Unread 08-02-2017, 08:15
GeeTwo's Avatar
GeeTwo GeeTwo is offline
Technical Director
AKA: Gus Michel II
FRC #3946 (Tiger Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Slidell, LA
Posts: 3,781
GeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond repute
Re: H-Drive Strafing issues

We tried strafe with H-drive in 2015, using a hard chassis mount. No matter how high or low we put it, it never worked right. Off season, we used a pneumatic cylinder to apply a steady force to it, and it worked first try. Springs can also work, I understand. The force on that wheel should be roughly between 20% and 35% of the weight of your robot, depending on how much strafe force you want and how much forward drive force you're willing to give up while you strafe.
__________________

If you can't find time to do it right, how are you going to find time to do it over?
If you don't pass it on, it never happened.
Robots are great, but inspiration is the reason we're here.
Friends don't let friends use master links.
Reply With Quote
  #8   Spotlight this post!  
Unread 08-02-2017, 09:59
messer5740's Avatar
messer5740 messer5740 is offline
Registered User
FRC #5740 (Trojanators)
Team Role: Driver
 
Join Date: Jan 2016
Rookie Year: 2015
Location: Pittsburgh
Posts: 142
messer5740 is an unknown quantity at this point
Re: H-Drive Strafing issues

Quote:
Originally Posted by GeeTwo View Post
We tried strafe with H-drive in 2015, using a hard chassis mount. No matter how high or low we put it, it never worked right. Off season, we used a pneumatic cylinder to apply a steady force to it, and it worked first try. Springs can also work, I understand. The force on that wheel should be roughly between 20% and 35% of the weight of your robot, depending on how much strafe force you want and how much forward drive force you're willing to give up while you strafe.
Think it would work if we just ran it on the carpet? We are using a Vex versaframe H drive chassis
__________________
A good driver is always better than a good robot.

2015: Winner of the Rookie Inspiration Award
2016: 8th seed alliance captain at Greater Pittsburgh Regional and 6th seed alliance captain at the Buckeye Regional
Thanks to all our alliance members!
Reply With Quote
  #9   Spotlight this post!  
Unread 08-02-2017, 10:04
Chris is me's Avatar
Chris is me Chris is me is offline
no bag, vex only, final destination
AKA: Pinecone
FRC #0228 (GUS Robotics); FRC #2170 (Titanium Tomahawks)
Team Role: Mentor
 
Join Date: Dec 2008
Rookie Year: 2006
Location: Glastonbury, CT
Posts: 7,797
Chris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond repute
Send a message via AIM to Chris is me
Re: H-Drive Strafing issues

Is the center wheel rigidly mounted to the frame, or is it articulated? An articulated strafe wheel will do a much better job contacting the ground. One COTS way to do this with VersaFrame would be to use a drop drive module with only one wheel in it (I've never tried this, it just seems like it would work).

If your frame uses VersaBlocks, be sure you don't accidentally have the drop center in the wrong direction.

A picture would really help here.
__________________
Mentor / Drive Coach: 228 (2016-?)
--2016 Waterbury SFs (with 3314, 3719), RIDE #2 Seed / Winners (with 1058, 6153), Carver QFs (with 503, 359, 4607)
Mentor / Consultant Person: 2170 (2017-?)
.
College Mentor: 2791 (2010-2015)
-- 2015 TVR Motorola Quality, FLR GM Industrial Design -- 2014 FLR Motorola Quality / SFs (with 341, 4930)
-- 2013 BAE Motorola Quality, WPI Regional #1 Seed / Delphi Excellence in Engineering / Finalists (with 20, 3182)
-- 2012 BAE Imagery / Finalists (with 1519, 885), CT Xerox Creativity / SFs (with 2168, 118)
Student: 1714 (2009) - 2009 MN 10K Lakes Regional Winners (with 2826, 2470)
2791 Build Season Photo Gallery - Look here for mechanism photos My Robotics Blog (Updated April 11 2014)
Reply With Quote
  #10   Spotlight this post!  
Unread 08-02-2017, 10:44
pmattin5459's Avatar
pmattin5459 pmattin5459 is offline
Registered User
AKA: Patrick Mattin
FRC #5459 (Ipswich TIGERS)
Team Role: Mentor
 
Join Date: Mar 2016
Rookie Year: 2015
Location: Massachusetts
Posts: 83
pmattin5459 will become famous soon enoughpmattin5459 will become famous soon enough
Re: H-Drive Strafing issues

Quote:
Originally Posted by messer5740 View Post
Think it would work if we just ran it on the carpet? We are using a Vex versaframe H drive chassis
He said that with a hard mount, no. You need some sort of actuation. I would suggest the RoboWrangler way from the comment above if you don't want to use pneumatics.
Reply With Quote
  #11   Spotlight this post!  
Unread 08-02-2017, 11:13
GeeTwo's Avatar
GeeTwo GeeTwo is offline
Technical Director
AKA: Gus Michel II
FRC #3946 (Tiger Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Slidell, LA
Posts: 3,781
GeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond repute
Re: H-Drive Strafing issues

Quote:
Originally Posted by messer5740 View Post
Think it would work if we just ran it on the carpet? We are using a Vex versaframe H drive chassis
Quote:
Originally Posted by pmattin5459 View Post
He said that with a hard mount, no. You need some sort of actuation. I would suggest the RoboWrangler way from the comment above if you don't want to use pneumatics.
Correct. It didn't matter whether we ran on bare floor or carpeting; we never got a useful strafe with fixed mounting, even when we tried a slot and use cable tension to hold the gearbox/wheel down.
__________________

If you can't find time to do it right, how are you going to find time to do it over?
If you don't pass it on, it never happened.
Robots are great, but inspiration is the reason we're here.
Friends don't let friends use master links.
Reply With Quote
  #12   Spotlight this post!  
Unread 08-02-2017, 11:20
messer5740's Avatar
messer5740 messer5740 is offline
Registered User
FRC #5740 (Trojanators)
Team Role: Driver
 
Join Date: Jan 2016
Rookie Year: 2015
Location: Pittsburgh
Posts: 142
messer5740 is an unknown quantity at this point
Re: H-Drive Strafing issues

Quote:
Originally Posted by GeeTwo View Post
Correct. It didn't matter whether we ran on bare floor or carpeting; we never got a useful strafe with fixed mounting, even when we tried a slot and use cable tension to hold the gearbox/wheel down.
So you suggest Vex Versadrop?
__________________
A good driver is always better than a good robot.

2015: Winner of the Rookie Inspiration Award
2016: 8th seed alliance captain at Greater Pittsburgh Regional and 6th seed alliance captain at the Buckeye Regional
Thanks to all our alliance members!
Reply With Quote
  #13   Spotlight this post!  
Unread 08-02-2017, 11:50
Chris Hibner's Avatar Unsung FIRST Hero
Chris Hibner Chris Hibner is offline
Eschewing Obfuscation Since 1990
AKA: Lars Kamen's Roadie
FRC #0051 (Wings of Fire (on sabbatical))
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1997
Location: Canton, MI
Posts: 1,489
Chris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond reputeChris Hibner has a reputation beyond repute
Re: H-Drive Strafing issues

When we did our H-drive in 2011 (which worked very well), our center wheel was on a simple suspension system. We put the center wheel on a swing arm and used a gas strut from McMaster Carr to provide the spring and damping. The trick was to size the gas strut to provide 1/5 of the robot's weight to the center wheel.
__________________
-
An ounce of perception is worth a pound of obscure.
Reply With Quote
  #14   Spotlight this post!  
Unread 08-02-2017, 11:58
GeeTwo's Avatar
GeeTwo GeeTwo is offline
Technical Director
AKA: Gus Michel II
FRC #3946 (Tiger Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Slidell, LA
Posts: 3,781
GeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond repute
Re: H-Drive Strafing issues

Quote:
Originally Posted by messer5740 View Post
So you suggest Vex Versadrop?
That would be one way, and the only COTS design that comes to mind. Our off season version was home brew, and not at all optimized, more a proof of concept. In some way, you need to have the wheel able to move up and down, and apply a relatively steady force to hold it down as it moves. Pneumatics gives you the option of lifting the strafe wheel up (or at least not pushing it down) to maximize traction on your primary drive wheels.
__________________

If you can't find time to do it right, how are you going to find time to do it over?
If you don't pass it on, it never happened.
Robots are great, but inspiration is the reason we're here.
Friends don't let friends use master links.
Reply With Quote
  #15   Spotlight this post!  
Unread 08-02-2017, 11:59
EricLeifermann's Avatar
EricLeifermann EricLeifermann is offline
That was a short break
FRC #2826 (Wave Robotics)
Team Role: Engineer
 
Join Date: Jan 2007
Rookie Year: 2001
Location: Wisconsin
Posts: 1,075
EricLeifermann has a reputation beyond reputeEricLeifermann has a reputation beyond reputeEricLeifermann has a reputation beyond reputeEricLeifermann has a reputation beyond reputeEricLeifermann has a reputation beyond reputeEricLeifermann has a reputation beyond reputeEricLeifermann has a reputation beyond reputeEricLeifermann has a reputation beyond reputeEricLeifermann has a reputation beyond reputeEricLeifermann has a reputation beyond reputeEricLeifermann has a reputation beyond repute
Re: H-Drive Strafing issues

Quote:
Originally Posted by Chris Hibner View Post
When we did our H-drive in 2011 (which worked very well), our center wheel was on a simple suspension system. We put the center wheel on a swing arm and used a gas strut from McMaster Carr to provide the spring and damping. The trick was to size the gas strut to provide 1/5 of the robot's weight to the center wheel.
If you don't have space for a gas shock constant force springs work well too.
__________________
2002-2005 Appleton East High School: Team 93
2005-2011 Michigan Technological University: Team 857
2012-Present Wave Robotics Team 2826



Reply With Quote
Reply


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 00:21.

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