Going over 6 inch step with 12 inch wheels

[KenWittlief]

if you have 4 wheel drive then when the front wheels hit the step the bot wants to do a wheelie, due to the torque on the rear wheels

but once the front wheels are up, and the back wheels hit the step, the bot wants to do the opponsite - the torque on the front wheels wants to push the back wheels down harder on the suface, making it harder for them to lift up onto the step

[Arefin Bari]

we are using the wheels from the kit... and we did have a problem getting up the 6" steps first... then we took some pressure out of the tire and it looks like the robot climbs real easily... if you want to see it... watch the last qualifying match @ midwest regional... i wish if i knew where you could find the video and i would post a link here too but unfortunately i am not sure... you can try robotics.nasa.gov ... if you need help come get me from 108's pit @ nat... or there is always something called AIM...

thanks to wildstang for bringing their practice field at midwest regional for which we were able to test how can we get up on the platform...

[jjdebner]

This may sound silly. But if you reduce the pressure in the tires to get more traction then if it is a four wheel drive system won't it jerk and jump when turning alot more. So it is basically a trade off between turning and climbing. Unless you have "special wheels". So just make sure you can still turn when you have some pressure taken out.

[tenfour]

Our team dropped some caster wheels off the back of the robot in such a way that they lift the rear of it of the ground. As the front wheels go up, the distance between the casters (attached to the rear of the frame) and the floor changes. Resulting, the robot rides on the casters instead of the back wheels when it straddles the step. This raises the height of the back wheels and allows them to climb easier. We also put HDPE "Sliders" on the front so that we can hit harder and carry ourselves up.

PM me if you need any clarification. Its a really easy process.

-Tenfour

[ngreen]

We also put HDPE "Sliders" on the front so that we can hit harder and carry ourselves up.

These are what is in the middle. You need to have a smooth movement up the stairs (can't stop and go, stop and go) because you need a little momentum. We chose to use non-powered wheels in front in hopes of not riding on balls really easily.

[Ryan Albright]

WEll if your robot has a arm what you could do is swing the arm forward. Thats what we had to do we get our front forks up and over and then we get closer pull up are back forks and swing are arm forward which puts more weight on the front giving the front wheels more grip

[Specialagentjim]

Originally Posted by jjdebner

This may sound silly. But if you reduce the pressure in the tires to get more traction then if it is a four wheel drive system won't it jerk and jump when turning alot more. So it is basically a trade off between turning and climbing. Unless you have "special wheels". So just make sure you can still turn when you have some pressure taken out.

We use a pnuematic cylindar with a delrin skid on the end to lift the robot's rear two wheels while turning. This enables us to have a 3 point turn, 2 being powered, the other being a skid. The piston ONLY engages (theoritically) during a turn, as defined by software. While going foreward (i.e. pushing, climbing), all four kit wheels are engaged on the ground for full torque/traction.

Definetly take some pressure out of the tires to climb. I'm also thinking more weight towards the front of the robot will help. We've found its not so much the diameter issue on the wheels, but the traction the tires get on the diamond plate. Our robot could climb up the side of a diamond plate wall until it reached the point where it would flip (around 12" high). By decreasing the pressure, you'll increase surface area of the wheel against the diamond plate. More surface area = more traction = more climbage (climbage a word?...dunno..)

If what I said makes sense, ALRIGHT! If not, lemme know!

[Mr. Ivey]

My team looked into doing this early in the year, here was our ideal. Put a skid leading to the back wheels, and put the weight in the front, creating a fulcrum along the skid, the weight on the front wheels will pull the front wheels to the platform, and pull you up the step. Simple, yet effective.
Ivey