Re: The Barrier Thread
 

If you had 6 inch wheels, you would still be able to drive up the rail like this.
http://www.youtube.com/watch?v=3qWYAOGZVM4
Not necessarily recommending it, but it is using small wheels to drive up a large obstacle.

If one was to use Gates belts, would tensioning them be a problem when the barrier pushed into them?

I think high centering could be a large problem. Could this be solved if you had a convex bottom part of your frame so it had a turtling effect (not stable so it doesn't balance when resting on the frame between the wheels)?

Re: The Barrier Thread
 

If anything, it would increase tension, possibly to the point of failure. Technically, this would be a "tensioning problem", but not the one people normally think of, also, it could easily be reduced by adding idlers to the belts where they are exposed so that the belt is pushed into the idler rather than into nothingness.

Re: The Barrier Thread
 

Anyone thinking of using a 2 wheel robot? I mean huge wheels like 20 or 24 inch bike wheels. I would understand how to keep it upright during operation, but before the match? Little omni wheels to support might help, but will hinder it going over anything.

Re: The Barrier Thread
 

yeah... after all of the people prototyping WCDs over the break, I wonder too... good luck using 4" wheels to cross the barrier...

Re: The Barrier Thread
 

Our team installed aluminum wheels at the front, which were able to sustain the weight of our full-weight robot coming down from the bump.

Re: The Barrier Thread
 

Our team is thinking of using four or six wheels, and using belts instead of chains. The belts will be backed on the bottom side by a flat panel, so that they can act as tank treads as they go over the barrier.

Re: The Barrier Thread
 

I was thinking something like this: http://www.youtube.com/watch?v=Ktw6AZU2Wtk&t=0m36s whatever drive you'd like+ the threads in front that are shown in this video.

Re: The Barrier Thread
 

One thing I noticed is the bumper rules this year. If I read correctly the bumpers have to exist somewhere between 2" and 10" from the ground. It seems to me there is only one location for the bumpers if you are trying to cross the bump. The top of the bumpers would have to be at 10" and going down to 5" off the ground. This is the only way that the bumpers won't hit the bump first. As well your frame perimeter would need to clear the bump as well so your wheels are the first thing to hit the bump. The KOP frame assembled with 6" wheels and per the provided instructions will NOT cross the bump even with brute force since the first thing to hit the bump would be either A) the bumpers if the lowest part of the bumper is below 4" OR B) the frame would hit the bump which would be flat vertical metal hitting flat vertical metal. The provided 6" wheels with no extra elevation of the frame would only lift the frame 3" off the ground (actually a little less than that).

Rookie teams please investigate this fully before putting together the KOP frame. You will only create extra work if you don't think about this before hand.

Re: The Barrier Thread
 

Step one: buy a segway. Done

Or you could use the same concept Dean's wheel chair does where it starts on 4 wheels and stands up on 2.

My only semi seriou idea with this is tristar wheels, but I think even that is overkill. http://orionrobots.co.uk/Tri+Star+Wheels

I think my team is plannig to have a ramp at the front of the chassis and actually having a frame with low ground clearance so we slide along the bottom rails of the chassis across the barrier. We think driving six wheels will keep us from getting stuck, and sliding would decrease the impacts and jarring of the robot.

Re: The Barrier Thread
 

This is only true in certain circumstances. It's not difficult to envision a situation where lower bumpers could be used, and yet the bump could still be traversed.

Re: The Barrier Thread
 

Are you thinking of a mechanism that extends past the bumper perimeter, like a foot or a wheel or a wedge?

Re: The Barrier Thread
 

It would be no fun if I revealed all my secrets... :)

Re: The Barrier Thread
 

Awwww.... shucks.

Re: The Barrier Thread
 

The last time I saw a mobility obstacle like this was in '04, I believe it was, when robots had to climb a couple of stairs to get up on to a central platform.

There were a number of ingenious solutions including some very nice treaded robots and the occasional one with some pneumatically activated "helper wheels" that would come down and lift the main wheels up on to the step.

But I agree that suspensions might be useful to have, too. I think that might be my first place to look.

Jason

Re: The Barrier Thread
 

Who said that a WCD has to have 4" wheels?

- Sunny G.