Go to Post The code won't compile if you violate the rules of the programming language...but English is more robust, it seems to work pretty well no matter how we engineering nerds mangle it! - MrForbes [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 02-02-2006, 16:30
TheAnsweris42's Avatar
TheAnsweris42 TheAnsweris42 is offline
Team 1896 "Rules Guru"
AKA: Kenneth Casperson
FRC #1896 (Xodus)
Team Role: Webmaster
 
Join Date: Jan 2006
Rookie Year: 2006
Location: Traverse City Michigan
Posts: 31
TheAnsweris42 will become famous soon enoughTheAnsweris42 will become famous soon enough
Send a message via ICQ to TheAnsweris42 Send a message via AIM to TheAnsweris42 Send a message via MSN to TheAnsweris42 Send a message via Yahoo to TheAnsweris42
Motors out of sync

We've finally recieved our two new CIM motors, and installed them on our robot. Our programming has a victor for each motor, as required, and is programmed so that each motor ought to run at the same speed as the one next to it, and all four should run at the same speed when the controller is pushed directly forward.

They don't. Not only do they not usually run at the same speed (at low speeds, especially, the robot will turn perpetually), but the motors mounted together in the gearboxes don't run at the same speed. We thought this was odd, but tried hooking it up for a few moments and running it with the wheels off the ground - it runs, even when on the ground, it will run fine, but it sounds so bad we took it back up on the cart. The problem is, we have NO IDEA how to get the motors to run in sync the way they should.

I hate to put it this way... but HELP!
__________________
"A common mistake people make when attempting to engineer something completely foolproof is to underestimate the ingenuity of complete fools"
-Douglas Nathaniel Adams
  #2   Spotlight this post!  
Unread 02-02-2006, 16:58
KenWittlief KenWittlief is offline
.
no team
Team Role: Engineer
 
Join Date: Mar 2003
Location: Rochester, NY
Posts: 4,213
KenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond repute
Re: Motors out of sync

Are the two motors mounted so they will turn in the same direction, or opposite?

motors seldom run at the same speed in opposite directions.

If that is not the issue, could one of the motors be defective? running slower than it should?

are you sure the Victors for each motor have been calibrated, and you are always sending the same output to both victors?
  #3   Spotlight this post!  
Unread 02-02-2006, 17:06
billbo911's Avatar
billbo911 billbo911 is offline
I prefer you give a perfect effort.
AKA: That's "Mr. Bill"
FRC #2073 (EagleForce)
Team Role: Mentor
 
Join Date: Mar 2005
Rookie Year: 2005
Location: Elk Grove, Ca.
Posts: 2,383
billbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond repute
Re: Motors out of sync

Quote:
Originally Posted by KenWittlief
.... are you sure the Victors for each motor have been calibrated, and you are always sending the same output to both victors?
Exactly where I was headed too. Make sure to calibrate the Victors as pairs. Another idea to keep the paired motors sync'd is to use a "Y" PWM cable to run the pair from a single PWM output. That way, the code only has to support one PWM per motor pair.
Just a suggestion.
__________________
CalGames 2009 Autonomous Champion Award winner
Sacramento 2010 Creativity in Design winner, Sacramento 2010 Quarter finalist
2011 Sacramento Finalist, 2011 Madtown Engineering Inspiration Award.
2012 Sacramento Semi-Finals, 2012 Sacramento Innovation in Control Award, 2012 SVR Judges Award.
2012 CalGames Autonomous Challenge Award winner ($$$).
2014 2X Rockwell Automation: Innovation in Control Award (CVR and SAC). Curie Division Gracious Professionalism Award.
2014 Capital City Classic Winner AND Runner Up. Madtown Throwdown: Runner up.
2015 Innovation in Control Award, Sacramento.
2016 Chezy Champs Finalist, 2016 MTTD Finalist
  #4   Spotlight this post!  
Unread 02-02-2006, 17:52
MattB703 MattB703 is offline
Registered User
AKA: Matt
None #0703 (Team Pheonix)
Team Role: Engineer
 
Join Date: Oct 2001
Rookie Year: 1998
Location: Saginaw, MI
Posts: 233
MattB703 has much to be proud ofMattB703 has much to be proud ofMattB703 has much to be proud ofMattB703 has much to be proud ofMattB703 has much to be proud ofMattB703 has much to be proud ofMattB703 has much to be proud ofMattB703 has much to be proud ofMattB703 has much to be proud ofMattB703 has much to be proud of
Re: Motors out of sync

Quote:
Originally Posted by TheAnsweris42
but the motors mounted together in the gearboxes don't run at the same speed.

I really don't understand this. Can you explain more?

If 2 motors are connected into the same gearbox how can they possibly be turning at different speeds? Aren't the physically coupled together so that a rotation on one MUST equal a rotation on the other?

Matt B.
  #5   Spotlight this post!  
Unread 02-02-2006, 21:17
Cody Carey's Avatar
Cody Carey Cody Carey is offline
,':-)
AKA: C. Carey
FRC #0306 (CRT)
Team Role: Alumni
 
Join Date: Feb 2005
Rookie Year: 2004
Location: Corry, PA
Posts: 1,137
Cody Carey has a reputation beyond reputeCody Carey has a reputation beyond reputeCody Carey has a reputation beyond reputeCody Carey has a reputation beyond reputeCody Carey has a reputation beyond reputeCody Carey has a reputation beyond reputeCody Carey has a reputation beyond reputeCody Carey has a reputation beyond reputeCody Carey has a reputation beyond reputeCody Carey has a reputation beyond reputeCody Carey has a reputation beyond repute
Send a message via AIM to Cody Carey Send a message via Yahoo to Cody Carey
Re: Motors out of sync

OK, if your drivetrain is making a sound kind of like that of a wounded bobcat at the YMCA, then that is a sure sign of something being wrong.

Some things to look for ( no matter how simple, they can still be overlooked )
1. One of the motors isn't hooked up backwards, the leads don't need to be reversed if you are using the kitbot Boxes.
2. check the RPM of each motor to make sure that they are all spinning the same without a load
3. if you've seel any magic smoke, check the brushes on the motor... in some cases they can be fixed, or defenately replaced
4. If you are using the kitbot boxes, make sure that no set screws have come loose
5. Make sure you are calibrating your Speed controlers correctly ( we had trouble with this a little)
6.As was said, Y cables are a good Idea, even if they do somewhat clutter your electronics up
7. If you are using the Kitboxes with two motors, try running them with only one.

Just definately make sure that your motors are spinning in the right direction and at the same speed, because if you pit CIM against CIM, one usually over powers the other, producing the terrible noise you might have heard when you put it on the ground and damaging stuff.

Sorry if this didn't help, I gave it my best shot





-CodyC
__________________

Last edited by Cody Carey : 02-02-2006 at 22:33.
  #6   Spotlight this post!  
Unread 03-02-2006, 22:49
Woodie Flowers Award
Ken Patton Ken Patton is offline
purple
FRC #0051 (Wings of Fire)
Team Role: Engineer
 
Join Date: Jul 2001
Rookie Year: 1997
Location: Pontiac, MI
Posts: 338
Ken Patton has a reputation beyond reputeKen Patton has a reputation beyond reputeKen Patton has a reputation beyond reputeKen Patton has a reputation beyond reputeKen Patton has a reputation beyond reputeKen Patton has a reputation beyond reputeKen Patton has a reputation beyond reputeKen Patton has a reputation beyond reputeKen Patton has a reputation beyond reputeKen Patton has a reputation beyond reputeKen Patton has a reputation beyond repute
Re: Motors out of sync

Kenneth-

The CIM motors and the gearboxes are pretty consistently good quality, and the problem you are describing sounds fairly big, so I would suggest that you consider two possibilities:

1. There is some serious friction caused by parts sliding together somewhere in the driveline.

or

2. The PWM signal from the controller is not the same to each of your speed controllers.

If its number 2, you should be able to check what your program is doing to see if there is some calculation error, and you should be able to see quickly if the speed controllers are going "full throttle" by looking at the red and green lights that signal full-back and full-forward.

If it is number one (my guess is that it is), you should look for parts that are rubbing against each other. Usually they tend to make noise, and heat up if you run them at high speed. Look at every interface in the driveline - is there a washer rubbing up against a bearing, is there a gear thats rubbing against something? Look to see if the gearbox was assembled correctly - lots of teams use it so it should be pretty straightforward for you to make yours right. Put the bot up on blocks, turn the wheels with your hands, feel for odd resistance against turning. Pull a motor out - if everything is running on ball bearings (and now no motor to resist you turning the wheel) the driveline should run super-free. If you feel drag or hear crunchy sounding noises you are probably getting close to the problem. Be a detective - you'll find it. I've seen experienced robo-nuts take a loong time to figure out where the problem is, so don't give up easily.

This might be a problem that you only see under load (like when the robot is pushing against something, or when you turn and the wheels scrub sideways). If this is the case you need to look for deflections in your chassis - are they causing shafts to come out of alignment? If so, FIX IT, make your chassis stiffer, you'll be glad you did. Are the wheels sliding sideways and rubbing up against something?

If you post your findings (try to be clear and concise, and explain your methods) you'll see that people will be willing to help you solve it through this forum.

Hope this helps,
Ken
  #7   Spotlight this post!  
Unread 04-02-2006, 08:22
TheAnsweris42's Avatar
TheAnsweris42 TheAnsweris42 is offline
Team 1896 "Rules Guru"
AKA: Kenneth Casperson
FRC #1896 (Xodus)
Team Role: Webmaster
 
Join Date: Jan 2006
Rookie Year: 2006
Location: Traverse City Michigan
Posts: 31
TheAnsweris42 will become famous soon enoughTheAnsweris42 will become famous soon enough
Send a message via ICQ to TheAnsweris42 Send a message via AIM to TheAnsweris42 Send a message via MSN to TheAnsweris42 Send a message via Yahoo to TheAnsweris42
Re: Motors out of sync

we took the gearboxes apart and made sure they were lubricated well, and all the parts seem to mesh fairly smoothly. Also, we did check the motors against a strobe the other day, and most of them run within a few RPM of one another, but one is BADLY off. I'm hoping its not a parts defect, we'll have to try recalibrating the Victor
__________________
"A common mistake people make when attempting to engineer something completely foolproof is to underestimate the ingenuity of complete fools"
-Douglas Nathaniel Adams

Last edited by TheAnsweris42 : 04-02-2006 at 08:27.
  #8   Spotlight this post!  
Unread 04-02-2006, 09:03
Unsung FIRST Hero
Mike Betts Mike Betts is offline
Electrical Engineer
no team
Team Role: Engineer
 
Join Date: Dec 2001
Rookie Year: 1995
Location: Homosassa, FL
Posts: 1,442
Mike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond reputeMike Betts has a reputation beyond repute
Re: Motors out of sync

Quote:
Originally Posted by TheAnsweris42
we took the gearboxes apart and made sure they were lubricated well, and all the parts seem to mesh fairly smoothly. Also, we did check the motors against a strobe the other day, and most of them run within a few RPM of one another, but one is BADLY off. I'm hoping its not a parts defect, we'll have to try recalibrating the Victor
Before you change anything, you can try swapping the "bad" motor with a good one. This will help identify if the issue is with the Victor or the motor.
__________________
Mike Betts

Alumnus, Team 3518, Panthrobots, 2011
Alumnus, Team 177, Bobcat Robotics, 1995 - 2010
LRI, Connecticut Regional, 2007-2010
LRI, WPI Regional, 2009 - 2010
RI, South Florida Regional, 2012 - 2013

As easy as 355/113...
  #9   Spotlight this post!  
Unread 04-02-2006, 17:07
TheAnsweris42's Avatar
TheAnsweris42 TheAnsweris42 is offline
Team 1896 "Rules Guru"
AKA: Kenneth Casperson
FRC #1896 (Xodus)
Team Role: Webmaster
 
Join Date: Jan 2006
Rookie Year: 2006
Location: Traverse City Michigan
Posts: 31
TheAnsweris42 will become famous soon enoughTheAnsweris42 will become famous soon enough
Send a message via ICQ to TheAnsweris42 Send a message via AIM to TheAnsweris42 Send a message via MSN to TheAnsweris42 Send a message via Yahoo to TheAnsweris42
Re: Motors out of sync

We don't have any more but the four we've got here... *sigh*

Ah well. We can try pulling one from the other box, I guess.
__________________
"A common mistake people make when attempting to engineer something completely foolproof is to underestimate the ingenuity of complete fools"
-Douglas Nathaniel Adams
  #10   Spotlight this post!  
Unread 06-02-2006, 15:41
TheAnsweris42's Avatar
TheAnsweris42 TheAnsweris42 is offline
Team 1896 "Rules Guru"
AKA: Kenneth Casperson
FRC #1896 (Xodus)
Team Role: Webmaster
 
Join Date: Jan 2006
Rookie Year: 2006
Location: Traverse City Michigan
Posts: 31
TheAnsweris42 will become famous soon enoughTheAnsweris42 will become famous soon enough
Send a message via ICQ to TheAnsweris42 Send a message via AIM to TheAnsweris42 Send a message via MSN to TheAnsweris42 Send a message via Yahoo to TheAnsweris42
Re: Motors out of sync

Okay, the gearboxes check fine, and the no one has been able to find anything wrong with the programming... so now what? Becuase if it's just a bad motor, we're kinda SOL - takes too long to order another...
__________________
"A common mistake people make when attempting to engineer something completely foolproof is to underestimate the ingenuity of complete fools"
-Douglas Nathaniel Adams
  #11   Spotlight this post!  
Unread 06-02-2006, 16:29
KenWittlief KenWittlief is offline
.
no team
Team Role: Engineer
 
Join Date: Mar 2003
Location: Rochester, NY
Posts: 4,213
KenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond repute
Re: Motors out of sync

what Mike was saying is, switch the wires between a good motor and the troubled motor, to the victors, to see if the problem follows the motors or the victors?
  #12   Spotlight this post!  
Unread 07-02-2006, 16:30
TheAnsweris42's Avatar
TheAnsweris42 TheAnsweris42 is offline
Team 1896 "Rules Guru"
AKA: Kenneth Casperson
FRC #1896 (Xodus)
Team Role: Webmaster
 
Join Date: Jan 2006
Rookie Year: 2006
Location: Traverse City Michigan
Posts: 31
TheAnsweris42 will become famous soon enoughTheAnsweris42 will become famous soon enough
Send a message via ICQ to TheAnsweris42 Send a message via AIM to TheAnsweris42 Send a message via MSN to TheAnsweris42 Send a message via Yahoo to TheAnsweris42
Thumbs down Re: Motors out of sync

Its the motor, as far as I can tell, but we've been using Easy C, and we can not figure out how to mess with the Victors at all using that program. So now we're trying to figure MP Lab out...
__________________
"A common mistake people make when attempting to engineer something completely foolproof is to underestimate the ingenuity of complete fools"
-Douglas Nathaniel Adams
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

Similar Threads
Thread Thread Starter Forum Replies Last Post
2 Globe Motors??? ChuckDickerson Motors 18 25-01-2005 15:53
Drill Motors Removed? Illegal this year? Chris_Elston Motors 12 12-01-2005 09:04
Looking for practice motors & extra tape drive parts? archiver 2000 1 23-06-2002 22:54
"Motors and Drive train edition" of Fresh From the Forum Ken Leung CD Forum Support 6 29-01-2002 12:32
Drill Motors TF8 Motors 19 12-12-2001 13:13


All times are GMT -5. The time now is 14:30.

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