Go to Post I'm frustrated by the world's reluctance to bend over backwards for FIRST. - Madison [more]
Home
Go Back   Chief Delphi > Technical > Motors
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 08-01-2012, 08:43
ttedrow's Avatar
ttedrow ttedrow is offline
Herding electrons
AKA: Tim Tedrow
FRC #0281 (EnTech)
Team Role: Mentor
 
Join Date: Jan 2002
Rookie Year: 2000
Location: Greenville, SC
Posts: 165
ttedrow will become famous soon enoughttedrow will become famous soon enough
Motor speed control uning Jaguar

Hi Techies,

I have been away from FRC for a while a I need a kick start with using the Jaguar. Our team's app will need highly accurate speed control for a ball shooter.

1) what speed sensor should we use?
2) what accuracy should we expect to achieve?
3) is there a recommended motor for shooter applications?

Thanks,
__________________
Sr. Design Engineer
Caterpillar Inc.
Greenville, SC

KD4EGM

FRC 281 Greenvillains
Infected with the FIRST virus in 2000

Yes, Chute Door!!!
  #2   Spotlight this post!  
Unread 08-01-2012, 12:45
slijin's Avatar
slijin slijin is offline
Pockets
AKA: Samuel Lijin
FRC #0694 (StuyPulse)
Team Role: Mentor
 
Join Date: Jan 2010
Rookie Year: 2010
Location: New York City
Posts: 537
slijin is a splendid one to beholdslijin is a splendid one to beholdslijin is a splendid one to beholdslijin is a splendid one to beholdslijin is a splendid one to beholdslijin is a splendid one to beholdslijin is a splendid one to behold
Re: Motor speed control uning Jaguar

Quote:
Originally Posted by ttedrow View Post
Hi Techies,

I have been away from FRC for a while a I need a kick start with using the Jaguar. Our team's app will need highly accurate speed control for a ball shooter.

1) what speed sensor should we use?
2) what accuracy should we expect to achieve?
3) is there a recommended motor for shooter applications?

Thanks,
There are a number of encoders to choose from for your speed sensor, namely the USDigital optical encoder and the magnetic encoders in last year's KoP.

Legal motors are listed in [R48], but I think it's a safe bet to say that you won't be using the Vex motor for your shooter.

Keep [R61] in mind though, because that specifically disallows the use of Jaguars' closed feedback loops.
__________________

2010-12 CT Chairman's
2011 Galileo 5th seed
2010 NY Regional Winners
  #3   Spotlight this post!  
Unread 08-01-2012, 21:04
ttedrow's Avatar
ttedrow ttedrow is offline
Herding electrons
AKA: Tim Tedrow
FRC #0281 (EnTech)
Team Role: Mentor
 
Join Date: Jan 2002
Rookie Year: 2000
Location: Greenville, SC
Posts: 165
ttedrow will become famous soon enoughttedrow will become famous soon enough
Re: Motor speed control uning Jaguar

Interesting. I wonder if they will change this like last year.

"As long as the CAN bus is wired legally so that the heartbeat from the cRIO is maintained, the closed loop control features of the Jaguar motor controller may be used. (That is, commands originating from the cRIO to configure, enable, and specify an operating point for all Jaguar closed loop modes fit the intent of <R49>.)
January 21, 2010"
__________________
Sr. Design Engineer
Caterpillar Inc.
Greenville, SC

KD4EGM

FRC 281 Greenvillains
Infected with the FIRST virus in 2000

Yes, Chute Door!!!
  #4   Spotlight this post!  
Unread 08-01-2012, 22:02
Thad House Thad House is online now
Volunteer, WPILib Contributor
no team (Waiting for 2021)
Team Role: Mentor
 
Join Date: Feb 2011
Rookie Year: 2010
Location: Thousand Oaks, California
Posts: 1,107
Thad House has a reputation beyond reputeThad House has a reputation beyond reputeThad House has a reputation beyond reputeThad House has a reputation beyond reputeThad House has a reputation beyond reputeThad House has a reputation beyond reputeThad House has a reputation beyond reputeThad House has a reputation beyond reputeThad House has a reputation beyond reputeThad House has a reputation beyond reputeThad House has a reputation beyond repute
Re: Motor speed control uning Jaguar

Quote:
Originally Posted by slijin View Post
There are a number of encoders to choose from for your speed sensor, namely the USDigital optical encoder and the magnetic encoders in last year's KoP.

Legal motors are listed in [R48], but I think it's a safe bet to say that you won't be using the Vex motor for your shooter.

Keep [R61] in mind though, because that specifically disallows the use of Jaguars' closed feedback loops.
How does R61 Disallow it. The blue box below R52 says otherwise.
__________________
All statements made are my own and not the feelings of any of my affiliated teams.
Teams 1510 and 2898 - Student 2010-2012
Team 4488 - Mentor 2013-2016
Co-developer of RobotDotNet, a .NET port of the WPILib.
  #5   Spotlight this post!  
Unread 08-01-2012, 22:11
StephenNutt StephenNutt is offline
Registered User
FRC #0172 (Falgor)
Team Role: Mentor
 
Join Date: Jan 2009
Rookie Year: 2007
Location: Falmouth, ME
Posts: 37
StephenNutt is an unknown quantity at this point
Re: Motor speed control uning Jaguar

Quote:
Originally Posted by sst.thad View Post
How does R61 Disallow it. The blue box below R52 says otherwise.
Agreed, seems explicitly allowed to me.
  #6   Spotlight this post!  
Unread 12-01-2012, 17:08
jwakeman jwakeman is offline
Registered User
FRC #0063 (Red Barons)
Team Role: Mentor
 
Join Date: Jan 2011
Rookie Year: 2010
Location: 16510
Posts: 182
jwakeman is just really nicejwakeman is just really nicejwakeman is just really nicejwakeman is just really nicejwakeman is just really nice
Re: Motor speed control uning Jaguar

I am looking for some clarification regarding this part of [R61]:

Quote:
A. The Jaguar must receive signals via either a PWM cable -OR- a CAN-bus connection. Both may not be used simultaneously.
Does this only apply to "command signals" that control the output of the jaguar? I might want to control the jag via PWM but monitor output voltage and current via CAN at the same time. Is this legal?
  #7   Spotlight this post!  
Unread 12-01-2012, 18:18
cgmv123's Avatar
cgmv123 cgmv123 is online now
FRC RI/FLL Field Manager
AKA: Max Vrany
FRC #1306 (BadgerBOTS)
Team Role: College Student
 
Join Date: Jan 2011
Rookie Year: 2011
Location: Madison, WI
Posts: 2,087
cgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond repute
Re: Motor speed control uning Jaguar

Quote:
Originally Posted by jwakeman View Post
Does this only apply to "command signals" that control the output of the jaguar? I might want to control the jag via PWM but monitor output voltage and current via CAN at the same time. Is this legal?
You can do whatever you want for testing. These rules only apply for a competing robot. That said, monitoring via CAN should be legal, but it's lawyering in my opinion.
__________________
BadgerBOTS Robotics|@team1306|Facebook: BadgerBOTS
2016 FIRST Championship Tesla Division | 2016 Wisconsin Regional Engineering Inspiration Award

2015 FIRST Championship Carson Division | 2015 Wisconsin Regional Chairman's Award

2013 FIRST Championship Curie Division | 2013 Wisconsin Regional Chairman's Award

2012 FIRST Championship Archimedes Division | 2012 Wisconsin Regional Engineering Inspiration Award, Woodie Flowers Finalist Award (Lead Mentor Ben Senson)

  #8   Spotlight this post!  
Unread 12-01-2012, 18:42
dez250 dez250 is offline
54... What a good number!
no team
 
Join Date: Dec 2002
Rookie Year: 2000
Location: Upstate NY / Manchester, NH
Posts: 1,721
dez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond repute
Send a message via AIM to dez250
Re: Motor speed control uning Jaguar

Would be? Should be? Could be? All three of those are grey area responses. You should post your question in the FRC Q&A Forum to get a legal explicit ruling from the GDC.
__________________
#5

-Michael Dessingue
  #9   Spotlight this post!  
Unread 12-01-2012, 19:22
cgmv123's Avatar
cgmv123 cgmv123 is online now
FRC RI/FLL Field Manager
AKA: Max Vrany
FRC #1306 (BadgerBOTS)
Team Role: College Student
 
Join Date: Jan 2011
Rookie Year: 2011
Location: Madison, WI
Posts: 2,087
cgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond repute
Re: Motor speed control uning Jaguar

Quote:
Originally Posted by dez250 View Post
Would be? Should be? Could be? All three of those are grey area responses. You should post your question in the FRC Q&A Forum to get a legal explicit ruling from the GDC.
Exactly, I'm not the GDC, therefore I can't give an official ruling. I can only offer up my interpretation accompanied by a qualifier.
__________________
BadgerBOTS Robotics|@team1306|Facebook: BadgerBOTS
2016 FIRST Championship Tesla Division | 2016 Wisconsin Regional Engineering Inspiration Award

2015 FIRST Championship Carson Division | 2015 Wisconsin Regional Chairman's Award

2013 FIRST Championship Curie Division | 2013 Wisconsin Regional Chairman's Award

2012 FIRST Championship Archimedes Division | 2012 Wisconsin Regional Engineering Inspiration Award, Woodie Flowers Finalist Award (Lead Mentor Ben Senson)

  #10   Spotlight this post!  
Unread 12-01-2012, 19:44
FrankJ's Avatar
FrankJ FrankJ is offline
Robot Mentor
FRC #2974 (WALT)
Team Role: Mentor
 
Join Date: Feb 2011
Rookie Year: 2009
Location: Marietta GA
Posts: 1,946
FrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond repute
Re: Motor speed control uning Jaguar

Rule 61 seems pretty clear to me. You can use either Can-Bus or PWM, but not both on the same Jaguar.
  #11   Spotlight this post!  
Unread 12-01-2012, 20:10
jwakeman jwakeman is offline
Registered User
FRC #0063 (Red Barons)
Team Role: Mentor
 
Join Date: Jan 2011
Rookie Year: 2010
Location: 16510
Posts: 182
jwakeman is just really nicejwakeman is just really nicejwakeman is just really nicejwakeman is just really nicejwakeman is just really nice
Re: Motor speed control uning Jaguar

Quote:
Originally Posted by FrankJ View Post
Rule 61 seems pretty clear to me. You can use either Can-Bus or PWM, but not both on the same Jaguar.
Another thought I had was to wire in both the PWM and the CAN. Then only use the CAN bus to control the robot. The PWM would be there as a failover drive system. I have some concerns about the CAN network being reliable annd want to be able to switch to PWM driving if we detect trouble. Not trying to bend the rules, just want to know what's legal. I will ask my question in the rule QA. Thanks
  #12   Spotlight this post!  
Unread 12-01-2012, 21:56
cgmv123's Avatar
cgmv123 cgmv123 is online now
FRC RI/FLL Field Manager
AKA: Max Vrany
FRC #1306 (BadgerBOTS)
Team Role: College Student
 
Join Date: Jan 2011
Rookie Year: 2011
Location: Madison, WI
Posts: 2,087
cgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond reputecgmv123 has a reputation beyond repute
Re: Motor speed control uning Jaguar

Quote:
Originally Posted by jwakeman View Post
Another thought I had was to wire in both the PWM and the CAN. Then only use the CAN bus to control the robot. The PWM would be there as a failover drive system. I have some concerns about the CAN network being reliable annd want to be able to switch to PWM driving if we detect trouble. Not trying to bend the rules, just want to know what's legal. I will ask my question in the rule QA. Thanks
That would not be legal. There is no way of knowing for sure that only one is controlling the robot.
__________________
BadgerBOTS Robotics|@team1306|Facebook: BadgerBOTS
2016 FIRST Championship Tesla Division | 2016 Wisconsin Regional Engineering Inspiration Award

2015 FIRST Championship Carson Division | 2015 Wisconsin Regional Chairman's Award

2013 FIRST Championship Curie Division | 2013 Wisconsin Regional Chairman's Award

2012 FIRST Championship Archimedes Division | 2012 Wisconsin Regional Engineering Inspiration Award, Woodie Flowers Finalist Award (Lead Mentor Ben Senson)

  #13   Spotlight this post!  
Unread 13-01-2012, 09:38
jwakeman jwakeman is offline
Registered User
FRC #0063 (Red Barons)
Team Role: Mentor
 
Join Date: Jan 2011
Rookie Year: 2010
Location: 16510
Posts: 182
jwakeman is just really nicejwakeman is just really nicejwakeman is just really nicejwakeman is just really nicejwakeman is just really nice
Re: Motor speed control uning Jaguar

Quote:
Originally Posted by dez250 View Post
Would be? Should be? Could be? All three of those are grey area responses. You should post your question in the FRC Q&A Forum to get a legal explicit ruling from the GDC.

I don't see any way on the Q&A to ask a question. I can only search..
  #14   Spotlight this post!  
Unread 13-01-2012, 09:53
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: Motor speed control uning Jaguar

Regarding speed sensors: An encoder is a good fit for this task. However, keep in mind how fast your wheel will be spinning.

Let's say your shooter is powered by a CIM and a 1:1 ratio. You will see ~5000rpm speed on the shooter wheel.

5000rpm is 83.3 revolutions per second. If you use the kit of parts encoders (250 counts per rev), that is more than 20,000 counts per second. In theory, the FPGA can count upwards of 39,000 counts per second. So this arrangement would work if you are doing speed control on the cRIO, but if you wanted to go to, say 10,000rpm on the shooter wheel, you would want a lower resolution encoder. I am not sure about the capabilities of a CAN Jaguar when it comes to maximum encoder rate.

In 2006, we made our own encoder by using an IR reflective sensor (like the ones Banner or Rockwell makes) with strips of reflective tape on the shooter wheel to trigger the counting. This method would of course work in 2012, as well.
  #15   Spotlight this post!  
Unread 13-01-2012, 13:32
dez250 dez250 is offline
54... What a good number!
no team
 
Join Date: Dec 2002
Rookie Year: 2000
Location: Upstate NY / Manchester, NH
Posts: 1,721
dez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond reputedez250 has a reputation beyond repute
Send a message via AIM to dez250
Re: Motor speed control uning Jaguar

Quote:
Originally Posted by jwakeman View Post
I don't see any way on the Q&A to ask a question. I can only search..
You will need the team account information from your team to post directly to ask a question. See the Q&A - How to Guide for more details.
__________________
#5

-Michael Dessingue
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 15:17.

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