View Single Post
  #25   Spotlight this post!  
Unread 20-01-2012, 23:02
BJC's Avatar
BJC BJC is offline
Simplicity is Complicated!
AKA: Bryan Culver
FRC #0033 (The Killer Bees)
Team Role: Alumni
 
Join Date: Jan 2010
Rookie Year: 2009
Location: Kettering/Greenville
Posts: 708
BJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond reputeBJC has a reputation beyond repute
Re: Mechanum Wheels?

Quote:
Originally Posted by DavidGitz View Post
I think what Chris is saying is that the axle would not hit the bump. Many other parts would hit the bump, and your argument is well founded but the axle itself will not hit, as it is within the perimeter of the mecanum wheel. Assuming of course that a) this is a *standard* mecanum setup b) the robot is attempting to drive straight on to the bump.
What I believe he is saying is that the midpoint of the wheel is level with the top of the barrier. Because of this the forces exerted by the robot must be entirely up until the wheel gains some purchase on the barrier and will continue to be able to pull the robot forward (read: over) the barrier.

If when your robot is climbing the barrier where the initial wheel contact with the barrier is lower then the middle of the wheel more forces remain pushing in the forward direction. In the same way, when you are on flat ground the wheels are pushing entirely forward. As a good rule of thumb if you can get the initial contact point inside the bottom 1/3 of the wheel that wheel will fairly easily surmount the point of contact while maintaining its forward force.

This is why it was suggested to put little ramps or something in front of your wheels. So the initial contact point of the barrier to the wheel is as low to the wheel as possible and forward momentum can be maintained.

Regards, Bryan
__________________
robot robot robot? Robot. Robot? Robot!
-----------------Team 33------------------

Last edited by BJC : 20-01-2012 at 23:12.
Reply With Quote