Go to Post FIRST, for me, is about mental wrestling with oneself through the ideas of others and learning through this dialogue. - sammyjalex [more]
Home
Go Back   Chief Delphi > Technical > Programming
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 07-01-2015, 13:37
pipsqueaker pipsqueaker is offline
Registered User
FRC #1124
 
Join Date: Apr 2013
Location: Avon
Posts: 59
pipsqueaker is a name known to allpipsqueaker is a name known to allpipsqueaker is a name known to allpipsqueaker is a name known to allpipsqueaker is a name known to allpipsqueaker is a name known to all
How many encoders are needed to control an H/slide drive?

We're planning on going an H drive this year, and our coder says that he wants five encoders, one on each wheel.

My interpretation of H-drive is basically that it is a tank drive with an extra wheel in the middle. This should mean that both wheels on the left and right are being driven in the same direction at the same rate- because of this I think that one encoder per side is fine, as the wheels will be driven with the same motors and gearboxes in an identical manner- our coder says that, because the two wheels on a side wont be driven by the same motor/gearbox, we will need to place an encoder on each wheel to correct for any tiny variations.

To me this seems excessive and inconvenient (5 encoders will take up all our DIO ports on the roborio, requiring me to expand it). I just wanted your opinions on whether we truly need an encoder on every single wheel.

EDIT: I should clarify, the encoders are for autonomous stuff, we're not really planning on using them in teleop
  #2   Spotlight this post!  
Unread 07-01-2015, 13:43
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)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1997
Location: Canton, MI
Posts: 1,488
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: How many encoders are needed to control an H/slide drive?

When we did ours in 2011, we used three encoders. It worked well.
__________________
-
An ounce of perception is worth a pound of obscure.
  #3   Spotlight this post!  
Unread 07-01-2015, 13:45
ASmith1675's Avatar
ASmith1675 ASmith1675 is offline
Mechanical/Electrical/Scouting
AKA: Adam Smith
FRC #1675 (Ultimate Protection Squad)
Team Role: Engineer
 
Join Date: Jan 2008
Rookie Year: 2005
Location: Milwaukee, WI
Posts: 48
ASmith1675 is a splendid one to beholdASmith1675 is a splendid one to beholdASmith1675 is a splendid one to beholdASmith1675 is a splendid one to beholdASmith1675 is a splendid one to beholdASmith1675 is a splendid one to beholdASmith1675 is a splendid one to beholdASmith1675 is a splendid one to behold
Re: How many encoders are needed to control an H/slide drive?

5 encoders certainly aren't NEEDED. 4 on the main drive will allow programmers to be able to speed match the 4 wheel, which will allow the best possible "drive straight" functionality in autonomous. You can get away with 2, but you won't be able to guarantee all 4 main drive motors are turning at the same rate then.

The 5th motor encoder would only be needed if you planned to do any strafing in autonomous.
  #4   Spotlight this post!  
Unread 07-01-2015, 13:46
RonnieS's Avatar
RonnieS RonnieS is offline
Just a tad washed up
AKA: Ronnie Sherrer
FRC #0314
Team Role: College Student
 
Join Date: Jan 2013
Rookie Year: 2006
Location: Flint/Warren
Posts: 389
RonnieS has a reputation beyond reputeRonnieS has a reputation beyond reputeRonnieS has a reputation beyond reputeRonnieS has a reputation beyond reputeRonnieS has a reputation beyond reputeRonnieS has a reputation beyond reputeRonnieS has a reputation beyond reputeRonnieS has a reputation beyond reputeRonnieS has a reputation beyond reputeRonnieS has a reputation beyond reputeRonnieS has a reputation beyond repute
Re: How many encoders are needed to control an H/slide drive?

Quote:
Originally Posted by Chris Hibner View Post
When we did ours in 2011, we used three encoders. It worked well.
2011 was flat, how do you feel about using three when trans-versing the bump, slippage on some wheels and not others affect anything?
DISCLAIMER: I am not a programmer, just interested.
__________________
"Do not argue with an idiot. He will drag you down to his level and beat you with experience"
  #5   Spotlight this post!  
Unread 07-01-2015, 13:49
nighterfighter nighterfighter is offline
1771 Alum, 1771 Mentor
AKA: Matt B
FRC #1771 (1771)
Team Role: Mentor
 
Join Date: Sep 2009
Rookie Year: 2007
Location: Suwanee/Kennesaw, GA
Posts: 835
nighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant future
Re: How many encoders are needed to control an H/slide drive?

You would want 5 encoders, if you were powering each wheel separately. But if you aren't going to power each wheel separately, that is a non-issue. I'd imagine you would want 3 total, for drive. One for the left side, with the encoder attached to the gearbox output shaft (Well, the little doohickey that sticks out for encoders), same thing for the right side, then one encoder on your center motor (for the H drive). (Not necessarily on the motor itself, of course. But I'm sure you know where to put it.)

Even if you wanted to use more than 5 or 6 encoders, without expanding the DIO ports on the roboRIO, the Jaguars DO have a built-in interface for encoders, that are accessible via CAN. (The Talons might have them also, you'll have to look that up).
__________________
1771- Programmer, Captain, Drive Team (2009-2012)
4509- Mentor (2013-2015)
1771- Mentor (2015)
  #6   Spotlight this post!  
Unread 07-01-2015, 17:04
Kevin Sevcik's Avatar
Kevin Sevcik Kevin Sevcik is offline
(Insert witty comment here)
FRC #0057 (The Leopards)
Team Role: Mentor
 
Join Date: Jun 2001
Rookie Year: 1998
Location: Houston, Texas
Posts: 3,745
Kevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond repute
Send a message via AIM to Kevin Sevcik Send a message via Yahoo to Kevin Sevcik
Re: How many encoders are needed to control an H/slide drive?

Quote:
Originally Posted by nighterfighter View Post
Even if you wanted to use more than 5 or 6 encoders, without expanding the DIO ports on the roboRIO, the Jaguars DO have a built-in interface for encoders, that are accessible via CAN. (The Talons might have them also, you'll have to look that up).
Talons. Talons, Talons, Talons. The encoder input on the Jags is nearly useless. It won't give you feedback unless you're actually using a closed-loop control mode. And its closed loop controls aren't all that great. And you can only use one encoder and one Jag to drive one motor, unless you're doing something to split the encoder signal, because there's no way to slave on Jag to another. Talons on the other hand give you a constant feedback stream of both velocity and position, so you could put the PID on your roboRIO, or use the PID on the Talon. And if you're in velocity mode, you can still get position feedback for all your autonomous needs.
__________________
The difficult we do today; the impossible we do tomorrow. Miracles by appointment only.

Lone Star Regional Troubleshooter
  #7   Spotlight this post!  
Unread 07-01-2015, 17:06
nighterfighter nighterfighter is offline
1771 Alum, 1771 Mentor
AKA: Matt B
FRC #1771 (1771)
Team Role: Mentor
 
Join Date: Sep 2009
Rookie Year: 2007
Location: Suwanee/Kennesaw, GA
Posts: 835
nighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant futurenighterfighter has a brilliant future
Re: How many encoders are needed to control an H/slide drive?

Quote:
Originally Posted by Kevin Sevcik View Post
Talons. Talons, Talons, Talons. The encoder input on the Jags is nearly useless. It won't give you feedback unless you're actually using a closed-loop control mode. And its closed loop controls aren't all that great. And you can only use one encoder and one Jag to drive one motor, unless you're doing something to split the encoder signal, because there's no way to slave on Jag to another. Talons on the other hand give you a constant feedback stream of both velocity and position, so you could put the PID on your roboRIO, or use the PID on the Talon. And if you're in velocity mode, you can still get position feedback for all your autonomous needs.
Okay cool! Like I said, I wasn't sure about the capabilities of Talons.

As for the closed loop part of the Jaguars, I suppose that's true. I've only ever used them with closed loop, I never anything else.
__________________
1771- Programmer, Captain, Drive Team (2009-2012)
4509- Mentor (2013-2015)
1771- Mentor (2015)
  #8   Spotlight this post!  
Unread 07-01-2015, 17:08
Kevin Sevcik's Avatar
Kevin Sevcik Kevin Sevcik is offline
(Insert witty comment here)
FRC #0057 (The Leopards)
Team Role: Mentor
 
Join Date: Jun 2001
Rookie Year: 1998
Location: Houston, Texas
Posts: 3,745
Kevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond reputeKevin Sevcik has a reputation beyond repute
Send a message via AIM to Kevin Sevcik Send a message via Yahoo to Kevin Sevcik
Re: How many encoders are needed to control an H/slide drive?

Quote:
Originally Posted by nighterfighter View Post
Okay cool! Like I said, I wasn't sure about the capabilities of Talons.

As for the closed loop part of the Jaguars, I suppose that's true. I've only ever used them with closed loop, I never anything else.
Actually I should amend that to Talon SRX. The original Talon and Talon SR controllers aren't CAN capable, after all.
__________________
The difficult we do today; the impossible we do tomorrow. Miracles by appointment only.

Lone Star Regional Troubleshooter
  #9   Spotlight this post!  
Unread 07-01-2015, 17:09
Bruceb's Avatar
Bruceb Bruceb is offline
Registered User
FRC #0706 (Cyberhawks)
Team Role: Mentor
 
Join Date: Jan 2008
Rookie Year: 2004
Location: Merton, wi
Posts: 616
Bruceb is a splendid one to beholdBruceb is a splendid one to beholdBruceb is a splendid one to beholdBruceb is a splendid one to beholdBruceb is a splendid one to beholdBruceb is a splendid one to beholdBruceb is a splendid one to behold
Re: How many encoders are needed to control an H/slide drive?

wont that center wheel on the H drive cause a problem going over the bump?
__________________
Mentor Team 706 The CyberHawks
2010 Wisconsin Regional Rockwell Automation Innovation in Control Award
2010 Wisconsin Regional Finalist
2013 Buckeye Regional Finalist
2014 Superior Regional Industrial Design Award
2014 Superior Regional Finalist
2014 Wisconsin Regional Finalist
2014 Wisconsin Motorola Quality Award
2015 Wisconsin Regional Motorola Quality Award
2015 Queen City Creativity Award
2016 Buckeye Regional Finalist
2016 Wisconsin Regional Finalist
2016 Wisconsin Regional Industrial Safety Award
2016 Wisconsin Regional Excellence in Engineering Award

https://www.youtube.com/user/Cyberhawks706
  #10   Spotlight this post!  
Unread 07-01-2015, 17:32
Jarren Harkema's Avatar
Jarren Harkema Jarren Harkema is offline
Dancing Drive Coach
FRC #4967 (That ONE Team)
Team Role: Mentor
 
Join Date: Sep 2013
Rookie Year: 2013
Location: Michigan
Posts: 167
Jarren Harkema is a name known to allJarren Harkema is a name known to allJarren Harkema is a name known to allJarren Harkema is a name known to allJarren Harkema is a name known to allJarren Harkema is a name known to all
Re: How many encoders are needed to control an H/slide drive?

Quote:
Originally Posted by Bruceb View Post
wont that center wheel on the H drive cause a problem going over the bump?
Only if it is in a fixed in position. Or... Are there other ways to obtain H drive motion with a different position/number of omni wheels?
  #11   Spotlight this post!  
Unread 07-01-2015, 17:49
jeremylee's Avatar
jeremylee jeremylee is offline
Registered User
FRC #2526 (Crimson Robotics)
Team Role: Mentor
 
Join Date: Feb 2013
Rookie Year: 2011
Location: Otsego, MN
Posts: 104
jeremylee is a jewel in the roughjeremylee is a jewel in the roughjeremylee is a jewel in the rough
Re: How many encoders are needed to control an H/slide drive?

Quote:
Originally Posted by Kevin Sevcik View Post
The encoder input on the Jags is nearly useless. It won't give you feedback unless you're actually using a closed-loop control mode.
1736 used Jags via CAN in 2012 and we were able to read speed while in open loop to implement PID on the cRIO. From BDC comm, I remember having to switch to closed loop, configure the encoder, and switch back to open loop to see speed. This wasn't an issue on the robot though.
  #12   Spotlight this post!  
Unread 07-01-2015, 19:02
Ether's Avatar
Ether Ether is offline
systems engineer (retired)
no team
 
Join Date: Nov 2009
Rookie Year: 1969
Location: US
Posts: 8,125
Ether has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond reputeEther has a reputation beyond repute
Re: How many encoders are needed to control an H/slide drive?

Quote:
Originally Posted by Jarren Harkema View Post
Are there other ways to obtain H drive motion with a different position/number of omni wheels?
Yes.

http://www.chiefdelphi.com/forums/sh...4&postcount=11

Also try searching for the words "Killough" and "Kiwi" here on CD


  #13   Spotlight this post!  
Unread 07-01-2015, 21:36
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)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1997
Location: Canton, MI
Posts: 1,488
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: How many encoders are needed to control an H/slide drive?

Quote:
Originally Posted by Ronnie314 View Post
2011 was flat, how do you feel about using three when trans-versing the bump, slippage on some wheels and not others affect anything?
DISCLAIMER: I am not a programmer, just interested.
We put the encoders on non-driven follower wheels that year. They were Vex omni-wheels mounted to tiny swing arms spring loaded to contact the ground. Therefore, no real worries about wheel slip.
__________________
-
An ounce of perception is worth a pound of obscure.
  #14   Spotlight this post!  
Unread 08-01-2015, 08:24
Jarren Harkema's Avatar
Jarren Harkema Jarren Harkema is offline
Dancing Drive Coach
FRC #4967 (That ONE Team)
Team Role: Mentor
 
Join Date: Sep 2013
Rookie Year: 2013
Location: Michigan
Posts: 167
Jarren Harkema is a name known to allJarren Harkema is a name known to allJarren Harkema is a name known to allJarren Harkema is a name known to allJarren Harkema is a name known to allJarren Harkema is a name known to all
Re: How many encoders are needed to control an H/slide drive?

Quote:
Originally Posted by Ether View Post
Yes.

http://www.chiefdelphi.com/forums/sh...4&postcount=11

Also try searching for the words "Killough" and "Kiwi" here on CD


Thanks Ether, though it was more of a question for BruceB and Pipsqueeker. Our team thinks we have figured out a way to use all omni and get over the scoring platform.
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 02:59.

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