Go to Post If this strategy backfires on any alliance that attempts it, they will have no one to blame but themselves. Be smart - know the risks before proceeding. - Travis Hoffman [more]
Home
Go Back   Chief Delphi > Old Forum Archives > 2001
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
 
 
Thread Tools Rate Thread Display Modes
Prev Previous Post   Next Post Next
  #26   Spotlight this post!  
Unread 24-06-2002, 00:21
archiver archiver is offline
Forum Archival System
#0047 (ChiefDelphi)
 
Join Date: May 2001
Location: Pontiac, MI
Posts: 21,214
archiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond reputearchiver has a reputation beyond repute
Re: Yes, there is a difference.

Posted by Dave... at 2/8/2001 9:03 PM EST


Engineer on team #5, Robocards, from Melvindale, MI and AFL (Alcoa Fujikura Ltd).


In Reply to: Yes, there is a difference.
Posted by Al Skierkiewicz on 2/7/2001 9:11 AM EST:



DC motors operate by inducing a magnetic field created by the armature within the magnetic field of the permanent magnets in the housing. As any elementary science teacher can attest to, a wire wrapped around a nail with DC current running through it will create a directional magnetic field, and by changing the polarity of the wires, the magnetic field will change 180° (N becomes S and vice versa).

The armature is wrapped with magnet wire from the inside out, and so running current in opposite directions will not only change the direction of the magnetic field from the armature, but will interact differently with the magnetic field from the permanent magnets, which does not get to change its directional field.

I imagine that a DC motor which does not use permanent magnets but rather windings in the housing to create the second magnetic field is not as susceptible to power loss in forward vs reverse. Both fields would change 180° any time the polarity was reversed, keeping roughly the same power in either direction.

We simply limit the power to the stronger drive motor by a trial and error method in the programming. If the robot steers to the right, we decrease the maximum power available to the left drive motor (e.g. p1_y = p1_y MAX 228) until the thing goes straight. Crude, but effective and easy to change.

My two cents worth.

: I have checked with Raul and Jim B and they HAVE experienced a variation in forward/reverse speed. In past years a thorough investigation showed as much as 10% variation in speed from unit to unit and forward/reverse. As Joe has suggested, (we agree) getting drivers to invest time behind the wheel is the best way to overcome the problem. I am still having a problem in analyzing why this occurs. Production variations can explain unit to unit changes but not for/rev. Any other input?
: Al


__________________
This message was archived from an earlier forum system. Some information may have been left out. Start new discussion in the current forums, and refer back to these threads when necessary.
 


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 Off
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Portable cordless drill press Gui Cavalcanti Technical Discussion 25 03-08-2003 22:21
drill motor mounts- again Jeff Sharpe Motors 6 07-04-2003 23:20
Emergency drill trade/sell Anarkissed General Forum 3 16-02-2003 22:37
Forward/Reverse difference in drill motors. archiver 2001 15 24-06-2002 02:38
"Motors and Drive train edition" of Fresh From the Forum Ken Leung CD Forum Support 6 29-01-2002 12:32


All times are GMT -5. The time now is 16:47.

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