Large wheel with omni-wheels

Has anyone created a drivetrain that uses a large wheel and omni-wheels? I haven’t been able to sort out the wheel placement in a way that I can keep the drivetrain parallel to the ground. Any suggestions?

The Omni wheels are the same size as the wheels on the claw-bot, right? I think they’re both 200mm (travel).

I think the boys on our team just moved the large wheels (250mm) up one hole. So, on a 2x?? beam, they put the omni wheel in the middle row of holes, and the 250mm in the top row.

However, it may not have been exactly right, because their robot had a pretty long wheel base, so the tilt may not have really shown up.

Steve

Hi crispierry,

Yes, if you stagger the 250mm and 200mm travel wheels vertically by one set holes of holes (0.25 inches) in a 2x beam it comes very close to being level. If you have six wheels on your robot with three on each side, and if the center wheel is the 250mm Travel Wheel and the outer wheels are 200mm Travel Wheels (or 200mm Travel Omni-Directional Wheels), this results in the center wheel being slightly lower than the two outer wheels, which is an advantageous feature and helps heavy robots turn better.

You can also power the 250mm and 200mm travel wheels together with the help of the 48 Tooth Gears that come in the HEXBUG VEX Robotics Ant kit. The ratio between the diameter of these two wheels is 5:4, so when they are geared at 4:5 to each other they will travel the same ground speed. You can get the 4:5 gear ratio with a 60 Tooth Gear on the 250mm travel wheel and 48 Tooth Gear on the 200mm travel wheel, like the attached photo shows.

Regards,

  • Art

    2014-11-21 - 250mm and 200mm Travel Wheels Geared Together.PNG.jpg

Thank you! This is exactly what I was doing, but we didn’t drive the robot. We will give it a try today!

Yes, if you stagger the 250mm and 200mm travel wheels vertically by one set holes of holes (0.25 inches) in a 2x beam it comes very close to being level. If you have six wheels on your robot with three on each side, and if the center wheel is the 250mm Travel Wheel and the outer wheels are 200mm Travel Wheels (or 200mm Travel Omni-Directional Wheels), this results in the center wheel being slightly lower than the two outer wheels, which is an advantageous feature and helps heavy robots turn better.