Go to Post For We Will Rock You, we quit counting Saturday morning when it got to 12 times. - Gary Dillard [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
  #1   Spotlight this post!  
Unread 23-06-2002, 22:42
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
6WD -- Highly recommended...

Posted by Joe Johnson at 1/16/2001 9:33 PM EST


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.


In Reply to: Re: A warning about tank steer
Posted by CArobot on 1/16/2001 6:25 PM EST:



Turning is a big reason to go with 6 wheel drive.

If you are trying to turn with 4WD or with a tank
drive, you are going to have to scrub your drive
mechanism across the floor.

If your front and back wheels are sharing the load
about equally, then you have a separation of about a
robot length between the scrub forces on the front and
back wheels. This puts a torque on your machine that
the drive system has to overcome. I have build a
number of robots that can barely turn at all without a
lot of heat being generated by the motors.

By going with 6WD, you effectly half the seperation
between the scrubbing forces. More than this, if you
look at the velocity vectors, you will see that in the
case of a square robot turning about its center with it
weight in the middle of the robot, the tires have to
move at a 45 degree angle to the direction of rolling.
Under the same situation for a 6WD robot with the
center wheels lowered so that they take more of the
load, there is almost no loss due to scubbing of the
wheels because the wheels that scrub are not loaded to
any significant amount.

Finally, considering the worst case of the CG half way
between two sets of wheels and a machine trying to spin
about its CG. Again, look at the velocity vectors.
Because distance between the drive wheels in the
fore/aft direction is about half the distance between
the wheels in the side to side direction, the velocity
vectors make a much smaller angle with the direction of
rolling of the wheels. This means less scrubbing.

BOTTOM LINE:

This is a great year to consider 6 wheel drive with the
middle wheels lowered a bit so the machine rock just
about a 1/4 inch.

Try it, you'll like it.

Joe J.



__________________
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
need glp programing steering with a steering wheel Matchew Programming 2 10-02-2003 14:20
What is crab steering?? Adam Y. Technical Discussion 18 30-12-2002 08:12
Under or Over? To tank or Not to tank that tis the question! archiver 2001 2 23-06-2002 22:53
Single Joystick Tank Steering archiver 2001 5 23-06-2002 22:49
tank steering archiver 2000 10 23-06-2002 22:28


All times are GMT -5. The time now is 19:21.

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