View Single Post
  #25   Spotlight this post!  
Unread 12-02-2013, 15:11
Jibri Wright's Avatar
Jibri Wright Jibri Wright is offline
Registered User
FRC #1781 (Electric Eagles)
Team Role: CAD
 
Join Date: Oct 2012
Rookie Year: 2011
Location: Chicago
Posts: 179
Jibri Wright will become famous soon enough
Re: How can you make turning smoother?

Quote:
Originally Posted by Jeffy View Post
While centripetal force exists, I'm not sure it does a lot for helping you turn on an FRC robot.
Also a test to show centripetal force is causing the better turning (or isn't) would be to decrease velocity of the turns and see if you notice more "scrubbing" due to a lower centripetal acceleration.

Also, I don't see a way that centripetal force/acceleration could be shown to be the reason an eight wheel drive with four dropped center wheels works.

Do a little search for "wheel base" on here and I'm sure you can find the reason drop center 6wd/8wd works the way it does.
While decreasing the velocity, it would skid more.

Looking at equations, (Fc=centripetal force, ac=centripetal acceleration)
Fc=m*ac
ac=lvl^2/r
So looking at this as circular speed decreases, so does the acceleration and in turn the centripetal force. Less centripetal force means less gravity it can counteract and balance.

As for the 8wd, the reason that works well is because the wheels that are pivoted on are close to the pivot point of the robot. This means that the frictional force they provide produce less torque on the robot than wheels that are further away from the pivot point. An example is something you all probably have used which is an allen wrench. If you tighten a screw with it with the long way in the screw, it gets hard to turn. You then turn it to put the short way in and it gets easier to tighten. This is the same thing happening here.