Go to Post If people really want to see "better" refereeing, they should see what they can do to help FIRST make better. - petek [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 Rating: Thread Rating: 4 votes, 5.00 average. Display Modes
  #76   Spotlight this post!  
Unread 01-08-2015, 23:37
Ari423's Avatar
Ari423 Ari423 is offline
LabVIEW aficionado and robot addict
AKA: The guy with the yellow hat
FRC #5987 (Galaxia)
Team Role: Mentor
 
Join Date: Mar 2015
Rookie Year: 2012
Location: Haifa, Israel
Posts: 656
Ari423 has much to be proud ofAri423 has much to be proud ofAri423 has much to be proud ofAri423 has much to be proud ofAri423 has much to be proud ofAri423 has much to be proud ofAri423 has much to be proud ofAri423 has much to be proud ofAri423 has much to be proud of
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by EDesbiens View Post
What would you guys use to know the position of the robot on the field at all time? And do you know any not drifting gyro?
For a non-drifting gyro we use the NavX which only drifts 2 or 3 degrees in a match. If you wanted to track position you could doubly integrate an accelerometer and combine that with the gyro, but again you will need a good accelerometer as doubly integrating adds even more opportunity for accumulated error.
__________________
2017-present: Mentor FRC 5987
2017-present: CSA for FIRST in Israel
2012-2016: Member FRC 423
2013: Programmer
2014: Head Programmer, Wiring
2015: Head Programmer, Wiring
2016: Captain, Head Programmer, Wiring, Manipulator, Chassis, CAD, Business, Outreach (basically everything)


  #77   Spotlight this post!  
Unread 01-08-2015, 23:41
EDesbiens's Avatar
EDesbiens EDesbiens is offline
Passionate crackpot
AKA: Étienne Desbiens
FRC #5859 (i)
Team Role: College Student
 
Join Date: Apr 2014
Rookie Year: 2013
Location: Canton de Hatley, QC, Canada
Posts: 297
EDesbiens is a glorious beacon of lightEDesbiens is a glorious beacon of lightEDesbiens is a glorious beacon of lightEDesbiens is a glorious beacon of lightEDesbiens is a glorious beacon of lightEDesbiens is a glorious beacon of light
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by Ari423 View Post
For a non-drifting gyro we use the NavX which only drifts 2 or 3 degrees in a match. If you wanted to track position you could doubly integrate an accelerometer and combine that with the gyro, but again you will need a good accelerometer as doubly integrating adds even more opportunity for accumulated error.
That is a lot more positive then the last comment... I'll try the NavX... Do you think that triangulation is a possible option? Maybe with a fisheye camera on top of a bot or something like that...
__________________
Lisa: Players play and managers manage.
Ralph: Do alligators alligate?
  #78   Spotlight this post!  
Unread 01-08-2015, 23:59
MichaelBick MichaelBick is offline
Registered User
FRC #1836 (MilkenKnights)
Team Role: Alumni
 
Join Date: Oct 2011
Rookie Year: 2010
Location: Los Angeles
Posts: 734
MichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant future
Re: Which sensors should be used throughout the robot?

Far better than integrating an accelerometer would be a non-driven omni wheel to track position
__________________
Team 1836 - The Milken Knights
2013 LA Regional Champions with 1717 and 973
2012 LA Regional Finalists with 294 and 973
To follow Team 1836 on Facebook, go to http://www.facebook.com/MilkenKnights
To go to our website, go to http://milkenknights.com/index.html
  #79   Spotlight this post!  
Unread 02-08-2015, 00:02
EDesbiens's Avatar
EDesbiens EDesbiens is offline
Passionate crackpot
AKA: Étienne Desbiens
FRC #5859 (i)
Team Role: College Student
 
Join Date: Apr 2014
Rookie Year: 2013
Location: Canton de Hatley, QC, Canada
Posts: 297
EDesbiens is a glorious beacon of lightEDesbiens is a glorious beacon of lightEDesbiens is a glorious beacon of lightEDesbiens is a glorious beacon of lightEDesbiens is a glorious beacon of lightEDesbiens is a glorious beacon of light
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by MichaelBick View Post
Far better than integrating an accelerometer would be a non-driven omni wheel to track position
But if the wheel slips?
__________________
Lisa: Players play and managers manage.
Ralph: Do alligators alligate?
  #80   Spotlight this post!  
Unread 02-08-2015, 02:43
MichaelBick MichaelBick is offline
Registered User
FRC #1836 (MilkenKnights)
Team Role: Alumni
 
Join Date: Oct 2011
Rookie Year: 2010
Location: Los Angeles
Posts: 734
MichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant futureMichaelBick has a brilliant future
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by EDesbiens View Post
But if the wheel slips?
As long as it isn't driven and is spring loaded down there should be no slip
__________________
Team 1836 - The Milken Knights
2013 LA Regional Champions with 1717 and 973
2012 LA Regional Finalists with 294 and 973
To follow Team 1836 on Facebook, go to http://www.facebook.com/MilkenKnights
To go to our website, go to http://milkenknights.com/index.html
  #81   Spotlight this post!  
Unread 02-08-2015, 03:35
marshall's Avatar
marshall marshall is online now
My pants are louder than yours.
FRC #0900 (The Zebracorns)
Team Role: Mentor
 
Join Date: Jan 2012
Rookie Year: 2003
Location: North Carolina
Posts: 1,330
marshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond repute
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by Ari423 View Post
For a non-drifting gyro we use the NavX which only drifts 2 or 3 degrees in a match. If you wanted to track position you could doubly integrate an accelerometer and combine that with the gyro, but again you will need a good accelerometer as doubly integrating adds even more opportunity for accumulated error.
Anecdotally, the new NavX firmware improves upon that drift.

Quote:
Originally Posted by EDesbiens View Post
That is a lot more positive then the last comment... I'll try the NavX... Do you think that triangulation is a possible option? Maybe with a fisheye camera on top of a bot or something like that...
I don't know that triangulation is the right term for this. I think you might be after something similar to Simultaneous Localization And Mapping (SLAM). SLAM is becoming more common in consumer and hobbyist robotics but it's still early days yet. I can tell you that it is something to keep digging into but I'm not sure it is the best area to invest resources into for an FRC team. It is definitely cool stuff though.
__________________
"La mejor salsa del mundo es la hambre" - Miguel de Cervantes
"The future is unwritten" - Joe Strummer
"Simplify, then add lightness" - Colin Chapman

Last edited by marshall : 02-08-2015 at 03:41.
  #82   Spotlight this post!  
Unread 02-08-2015, 15:25
slibert slibert is offline
Software Mentor
AKA: Scott Libert
FRC #2465 (Kauaibots)
Team Role: Mentor
 
Join Date: Oct 2011
Rookie Year: 2005
Location: Kauai, Hawaii
Posts: 356
slibert has much to be proud ofslibert has much to be proud ofslibert has much to be proud ofslibert has much to be proud ofslibert has much to be proud ofslibert has much to be proud ofslibert has much to be proud ofslibert has much to be proud ofslibert has much to be proud of
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by EDesbiens View Post
That is a lot more positive then the last comment... I'll try the NavX... Do you think that triangulation is a possible option? Maybe with a fisheye camera on top of a bot or something like that...
The triangulation approach you mention has been done w/active landmarks like wireless beacons (requiring installation of multiple wifi transmitters), passive landmarks (well-known "checkerboard" patterns at well-known positions, w/identification/range calculated by a scanning camera), and by systems not dependent upon landmarks, including range-finding vision sensors (stereoscopic cameras, structured light sensors like Kinect [which are very short range, e.g. a living room], scanning LIDAR sensors, and scanning (or alternatively fisheye lens, as you say) video camers w/image recognition.

The optical approaches are non-trivial, rarely used in FIRST, and typically considered university-level. So a lot of folks tend to get a funny look on their face when these topics are discussed, and wonder why we're making things so complicated.

The algorthms for localization are becoming more and more available online, and there's free online courseware from MIT in probabilistic localization and related technologies.

More close to home, the Zebracorns have published as open source their 2015 vision software, which used OpenCV-based classifiers that were trained to recognize game pieces, pushing forward the State of the Art in vision processing in FIRST. If the same approach were used to recognize fixed-position field pieces, and then range to those objects was calculated and fused w/a map of the field (known ahead of time, in FIRST), you'd have what you were looking for. Again, not-trivial, but for those with interest, worth looking into in my opinion.

Looking ahead, a colleague of mine pointed out this fascinating new research from MIT that fuses object recognition with SLAM.
  #83   Spotlight this post!  
Unread 09-08-2015, 21:26
thatprogrammer's Avatar
thatprogrammer thatprogrammer is offline
Registered User
AKA: Ahad Bawany
no team (None)
Team Role: Programmer
 
Join Date: Apr 2014
Rookie Year: 2014
Location: Florida
Posts: 610
thatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond repute
Re: Which sensors should be used throughout the robot?

I just thought of something (apologies if it has already been mentioned and I've missed it), could you not use a hall effect sensors to count wheel revolutions? It seems like a simpler solution than using a banner sensor.
  #84   Spotlight this post!  
Unread 09-08-2015, 23:35
Gdeaver Gdeaver is online now
Registered User
FRC #1640
Team Role: Mentor
 
Join Date: Mar 2004
Rookie Year: 2001
Location: West Chester, Pa.
Posts: 1,370
Gdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond repute
Re: Which sensors should be used throughout the robot?

We did this in 2014 on our swerve modules. 6 neodymium magnets were mounted alternating north south on the under side of the 3.5" timming belt pulley. A Melexis US2881 Latching hall sensor was then used to give a non-contact solution. A counter was used set up for counting on the rising and falling edge. We used this to measure distance traveled. This year we used these boards.
https://www.pololu.com/product/2458
12 strips of KOP retroflective tape were mounted under the pulley. Although this is listed as an analog device, The c-rio did the chopping on a digital input set up as a counter.
  #85   Spotlight this post!  
Unread 10-08-2015, 21:22
thatprogrammer's Avatar
thatprogrammer thatprogrammer is offline
Registered User
AKA: Ahad Bawany
no team (None)
Team Role: Programmer
 
Join Date: Apr 2014
Rookie Year: 2014
Location: Florida
Posts: 610
thatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond reputethatprogrammer has a reputation beyond repute
Re: Which sensors should be used throughout the robot?

I noticed that we haven't mentioned using camera in this thread. What cameras have teams used, and how have they found them?
  #86   Spotlight this post!  
Unread 21-08-2015, 19:34
garyk garyk is offline
Programming Mentor: 668, 972, 2643
FRC #0668 (Apes of Wrath)
Team Role: Mentor
 
Join Date: Dec 2006
Rookie Year: 2005
Location: Santa Clara (Silicon Valley) Calif.
Posts: 94
garyk is a jewel in the roughgaryk is a jewel in the roughgaryk is a jewel in the roughgaryk is a jewel in the rough
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by jajabinx124 View Post
Reed switches and limit switches are both digital inputs that return boolean states, so both would be programmed the same.
Just to clarify - a "limit switch" is not a special kind of switch, it's a switch that we use to limit motion. One doesn't buy a "limit switch", you choose among microswitches, optical switches, magnetic [reed] switches, ..., for a switch that mechanically fits and triggers at that point in the motion of whatever you need to stop on your robot. They are not wired directly to a motor, but to a Digital Input on the roboRIO/cRIO/Arduino, etc. The program running on that computer will sense that the switch has opened/closed and will control that motor's Jaguar/Victor/Talon speed controller appropriately.
__________________

Silicon Valley Regional 2005, 2006 972
Silicon Valley Regional 2007 668 Xerox Creativity Award
Championship Event 2007 668
Portland Regional 2008 668
Silicon Valley Regional 2008 668, 972
Beta Test Team 2008 668 (with 100 & 254)
Silicon Valley Regional 2009 668 Regional Chairman's Award; 2643
Sacramento Regional 2009 668 Winning Alliance (thanks, 1717 & 2473!), 2010 Winning Alliance 3256
CalGames 2006, 2007, 2008, 2009, 2010, 2011 Field Tech
NorCal FTC Regional 2008, 2009 Inspector
Championship Event 2009
San Diego, Silicon Valley Regionals; Champ. Event 2010 668, 2643, 3256
Silicon Valley, Madera Regional 2012 2643
WRRF Programming Instructor 2006-2016
Regional Woodie Flowers Award 2014 2643 Utah Regional

  #87   Spotlight this post!  
Unread 21-08-2015, 20:02
garyk garyk is offline
Programming Mentor: 668, 972, 2643
FRC #0668 (Apes of Wrath)
Team Role: Mentor
 
Join Date: Dec 2006
Rookie Year: 2005
Location: Santa Clara (Silicon Valley) Calif.
Posts: 94
garyk is a jewel in the roughgaryk is a jewel in the roughgaryk is a jewel in the roughgaryk is a jewel in the rough
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by Thad House View Post
So the input shaft of the encoder is 1/4 inch. So its press fit in. Then teams zip tie the wires down, which stops the housing from spinning.
Oh, geez, let's not do this - anchoring the housing/body of the encoder via securing its wires (and I've seen it). If you're using an encoder with 360 counts/rev for example, a wobble of one degree is one count. Although we're not going to use them ($$$) encoders are available with > 10K counts/rev. and imagine the error if it's poorly mounted. What you are learning (and I'm supposed to be teaching) should be applicable to an engineering job. Please mount encoders such that the threads on its body go through an appropriately-sized hole, and secure it with the lock washer and nut that come with the encoder. Have this in your CAD!

It's a good idea to mark the position of the encoder on its mount by drawing a line (sharpie, etc.) from the body of the encoder onto its bracket/panel, same thing for a pot. That way, if it comes loose (as did ours at Champs in 2010) you can put it back in about the right place, until you have time between matches to accurately remount it.
__________________

Silicon Valley Regional 2005, 2006 972
Silicon Valley Regional 2007 668 Xerox Creativity Award
Championship Event 2007 668
Portland Regional 2008 668
Silicon Valley Regional 2008 668, 972
Beta Test Team 2008 668 (with 100 & 254)
Silicon Valley Regional 2009 668 Regional Chairman's Award; 2643
Sacramento Regional 2009 668 Winning Alliance (thanks, 1717 & 2473!), 2010 Winning Alliance 3256
CalGames 2006, 2007, 2008, 2009, 2010, 2011 Field Tech
NorCal FTC Regional 2008, 2009 Inspector
Championship Event 2009
San Diego, Silicon Valley Regionals; Champ. Event 2010 668, 2643, 3256
Silicon Valley, Madera Regional 2012 2643
WRRF Programming Instructor 2006-2016
Regional Woodie Flowers Award 2014 2643 Utah Regional

  #88   Spotlight this post!  
Unread 21-08-2015, 20:09
tickspe15's Avatar
tickspe15 tickspe15 is offline
Purdue University
AKA: Spencer Tickman
FRC #1747 (Harrison Boiler Robotics)
Team Role: Mentor
 
Join Date: Nov 2011
Rookie Year: 2009
Location: Issaquah, Washington
Posts: 253
tickspe15 has a brilliant futuretickspe15 has a brilliant futuretickspe15 has a brilliant futuretickspe15 has a brilliant futuretickspe15 has a brilliant futuretickspe15 has a brilliant futuretickspe15 has a brilliant futuretickspe15 has a brilliant futuretickspe15 has a brilliant futuretickspe15 has a brilliant futuretickspe15 has a brilliant future
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by garyk View Post
Oh, geez, let's not do this - anchoring the housing/body of the encoder via securing its wires (and I've seen it). If you're using an encoder with 360 counts/rev for example, a wobble of one degree is one count. Although we're not going to use them ($$$) encoders are available with > 10K counts/rev. and imagine the error if it's poorly mounted. What you are learning (and I'm supposed to be teaching) should be applicable to an engineering job. Please mount encoders such that the threads on its body go through an appropriately-sized hole, and secure it with the lock washer and nut that come with the encoder. Have this in your CAD!

It's a good idea to mark the position of the encoder on its mount by drawing a line (sharpie, etc.) from the body of the encoder onto its bracket/panel, same thing for a pot. That way, if it comes loose (as did ours at Champs in 2010) you can put it back in about the right place, until you have time between matches to accurately remount it.
It seemed to work well enough for 254 😜
__________________
Team 1318: 2011-2015
Team 1747: 2015-Present
NAR (VEX U): 2015-Present
  #89   Spotlight this post!  
Unread 21-08-2015, 20:40
marshall's Avatar
marshall marshall is online now
My pants are louder than yours.
FRC #0900 (The Zebracorns)
Team Role: Mentor
 
Join Date: Jan 2012
Rookie Year: 2003
Location: North Carolina
Posts: 1,330
marshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond reputemarshall has a reputation beyond repute
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by tickspe15 View Post
It seemed to work well enough for 254 😜
They have also since said that they have implemented more secure techniques to deal with the backlash.
__________________
"La mejor salsa del mundo es la hambre" - Miguel de Cervantes
"The future is unwritten" - Joe Strummer
"Simplify, then add lightness" - Colin Chapman
  #90   Spotlight this post!  
Unread 21-08-2015, 20:55
garyk garyk is offline
Programming Mentor: 668, 972, 2643
FRC #0668 (Apes of Wrath)
Team Role: Mentor
 
Join Date: Dec 2006
Rookie Year: 2005
Location: Santa Clara (Silicon Valley) Calif.
Posts: 94
garyk is a jewel in the roughgaryk is a jewel in the roughgaryk is a jewel in the roughgaryk is a jewel in the rough
Re: Which sensors should be used throughout the robot?

Quote:
Originally Posted by tickspe15 View Post
It seemed to work well enough for 254 😜
It's also going to work in your first engineering job if your goal is not to get a raise
__________________

Silicon Valley Regional 2005, 2006 972
Silicon Valley Regional 2007 668 Xerox Creativity Award
Championship Event 2007 668
Portland Regional 2008 668
Silicon Valley Regional 2008 668, 972
Beta Test Team 2008 668 (with 100 & 254)
Silicon Valley Regional 2009 668 Regional Chairman's Award; 2643
Sacramento Regional 2009 668 Winning Alliance (thanks, 1717 & 2473!), 2010 Winning Alliance 3256
CalGames 2006, 2007, 2008, 2009, 2010, 2011 Field Tech
NorCal FTC Regional 2008, 2009 Inspector
Championship Event 2009
San Diego, Silicon Valley Regionals; Champ. Event 2010 668, 2643, 3256
Silicon Valley, Madera Regional 2012 2643
WRRF Programming Instructor 2006-2016
Regional Woodie Flowers Award 2014 2643 Utah Regional

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 12:57.

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