Go to Post Right now, it drives around....hopefully tomorrow it will do a LOT more! - MrForbes [more]
Home
Go Back   Chief Delphi > Technical > Electrical
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
  #16   Spotlight this post!  
Unread 24-03-2011, 22:41
Kingofl337's Avatar
Kingofl337 Kingofl337 is offline
You didn't see anything....
AKA: Adam
FRC #0501 (Power Knights)
Team Role: Mentor
 
Join Date: Feb 2005
Rookie Year: 1998
Location: Manchester, NH
Posts: 861
Kingofl337 has a reputation beyond reputeKingofl337 has a reputation beyond reputeKingofl337 has a reputation beyond reputeKingofl337 has a reputation beyond reputeKingofl337 has a reputation beyond reputeKingofl337 has a reputation beyond reputeKingofl337 has a reputation beyond reputeKingofl337 has a reputation beyond reputeKingofl337 has a reputation beyond reputeKingofl337 has a reputation beyond reputeKingofl337 has a reputation beyond repute
Send a message via Yahoo to Kingofl337
Re: Walking Encoder Values

Can you use a multi-turn POT instead?
__________________
FIRST Team 501 PowerKnights - Mentor
FIRST Team 40 Checkmate - Mentor Alum
FIRST Team 146 Blue Lightning - Alumni
  #17   Spotlight this post!  
Unread 24-03-2011, 23:14
mikets's Avatar
mikets mikets is offline
Software Engineer
FRC #0492 (Titan Robotics)
Team Role: Mentor
 
Join Date: Jan 2010
Rookie Year: 2008
Location: Bellevue, WA
Posts: 675
mikets is a glorious beacon of lightmikets is a glorious beacon of lightmikets is a glorious beacon of lightmikets is a glorious beacon of lightmikets is a glorious beacon of lightmikets is a glorious beacon of light
Re: Walking Encoder Values

The optical encoder comes with a centering tool and a disc spacing tool. If you follow the instructions correctly in using those tools, you should not have any problem. We have a student that did not use those tools when assembling the encoder. He pressed the optical disc all the way down and ended up scratching it. So our autonomous acted strangely. After scratching our heads for a while, I finally pulled out the encoder and examined the disc and found the problem. Once we replaced the disc, everything worked fine.
__________________
  #18   Spotlight this post!  
Unread 24-03-2011, 23:26
pfreivald's Avatar
pfreivald pfreivald is offline
Registered User
AKA: Patrick Freivald
FRC #1551 (The Grapes of Wrath)
Team Role: Mentor
 
Join Date: Jan 2007
Rookie Year: 2001
Location: Naples, NY
Posts: 2,304
pfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond repute
Re: Walking Encoder Values

Quote:
Originally Posted by mikets View Post
The optical encoder comes with a centering tool and a disc spacing tool. If you follow the instructions correctly in using those tools, you should not have any problem. We have a student that did not use those tools when assembling the encoder. He pressed the optical disc all the way down and ended up scratching it. So our autonomous acted strangely. After scratching our heads for a while, I finally pulled out the encoder and examined the disc and found the problem. Once we replaced the disc, everything worked fine.
Are you kidnapping my students and making them install sensors on your robot?
__________________
Patrick Freivald -- Mentor
Team 1551
"The Grapes of Wrath"
Bausch & Lomb, PTC Corporation, and Naples High School

I write books, too!
  #19   Spotlight this post!  
Unread 25-03-2011, 03:14
mikets's Avatar
mikets mikets is offline
Software Engineer
FRC #0492 (Titan Robotics)
Team Role: Mentor
 
Join Date: Jan 2010
Rookie Year: 2008
Location: Bellevue, WA
Posts: 675
mikets is a glorious beacon of lightmikets is a glorious beacon of lightmikets is a glorious beacon of lightmikets is a glorious beacon of lightmikets is a glorious beacon of lightmikets is a glorious beacon of light
Re: Walking Encoder Values

Quote:
Originally Posted by pfreivald View Post
Are you kidnapping my students and making them install sensors on your robot?
Is it why we keep losing our games?
__________________
  #20   Spotlight this post!  
Unread 25-03-2011, 07:54
Jared Russell's Avatar
Jared Russell Jared Russell is offline
Taking a year (mostly) off
FRC #0254 (The Cheesy Poofs), FRC #0341 (Miss Daisy)
Team Role: Engineer
 
Join Date: Nov 2002
Rookie Year: 2001
Location: San Francisco, CA
Posts: 3,082
Jared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond repute
Re: Walking Encoder Values

My suspects would be, in order:

1. Mechanical slippage between the encoder and the shaft whose rotation it is measuring (you seem fairly sure that this isn't the issue, and I believe you, but in general it is the first/easiest thing to check)

2. Improper spacing between the optical disc and the encoder circuitry. Use a spacer tool when installing the disc.

3. A "smudge" (fingerprint or scratch) on the disc that causes one of the photoreflectors to miss a count or two per revolution. Easiest solution: try another encoder disc.

4. EMI/wiring problem.

5. Code issue. Your code doesn't ever reset the encoder, does it?

6. An absurd pulse frequency (too high of a CPR on the encoder given the speed of the shaft it is measuring). However, in the cRIO era, you need to be well into the tens-of-thousands of pulses per second before this would be an issue, so it is unlikely.

Last edited by Jared Russell : 25-03-2011 at 10:54.
  #21   Spotlight this post!  
Unread 25-03-2011, 10:46
Bryany's Avatar
Bryany Bryany is offline
Registered User
FRC #1094 (Channel Cats)
Team Role: Programmer
 
Join Date: Mar 2011
Rookie Year: 2011
Location: St. Charles
Posts: 67
Bryany is a jewel in the roughBryany is a jewel in the roughBryany is a jewel in the roughBryany is a jewel in the rough
Re: Walking Encoder Values

This might not be what's causing your problems, but on our robot, the encoder would be missing ticks off and on; it would read for one second, then it would pause, then it would read some more, and so on. The encoder was plugged in all the way, but we found that the problem was because the wire was going into the encoder at an angle. (that the wire coming off at an angle was pulling the encoder out of a proper connection) We taped the wire so that it comes out straight and haven't had any problems since.
  #22   Spotlight this post!  
Unread 25-03-2011, 14:06
pfreivald's Avatar
pfreivald pfreivald is offline
Registered User
AKA: Patrick Freivald
FRC #1551 (The Grapes of Wrath)
Team Role: Mentor
 
Join Date: Jan 2007
Rookie Year: 2001
Location: Naples, NY
Posts: 2,304
pfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond reputepfreivald has a reputation beyond repute
Re: Walking Encoder Values

Quote:
Originally Posted by Bryany View Post
(that the wire coming off at an angle was pulling the encoder out of a proper connection) We taped the wire so that it comes out straight and haven't had any problems since.
All wires should have a strain relief!
__________________
Patrick Freivald -- Mentor
Team 1551
"The Grapes of Wrath"
Bausch & Lomb, PTC Corporation, and Naples High School

I write books, too!
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 18:57.

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