Drivetrain:
Our team is going with a hybrid drive train this year. A drive train that has the torque and pushing strength of small traction wheels, and the maneuverability of mechanic wheels.
It was inspired by team #3928 Team Neutrino’s “Butterfly Drive” system they used on their 2013 robot.
(http://www.teamneutrino.org/seasons/ultimate-ascent/robot/butterfly/)
Team Neutrino used a dual omni wheel-plaction wheel combo, whereas our design will use a combination of 6 inch vexpro mechanum wheels and 4 inch andymark am-0435 plaction wheels.
The mechanum wheels will be geared at a very low ratio, with speed and manueverability in mind, and our plaction wheels will be geared at a high ratio, with torque and pushing power in mind.
The default wheel set is the mechanum wheels, and to switch to the plaction wheels, we will fire the small pneumatic cylinder pictured above on the right. The actuation of that cylinder will push the plaction wheel onto the ground, and in the process lift the entire robot a few more inches of the ground.
And that’s going to happen inside each drive module on all four corners of the robot at the same time.
Our game plan is to stay on the mechanum wheels for the majority of the game, and switch to the more torquey set of wheels when another robot is trying to push us around, or when we want to push another robot around. And once we push through, we’re going to vent the cylinder, raising the plaction wheels and lowering the mechanum wheels back to the ground.
It’s going to be useful to have both strength and maneuverability in this year’s competition. It’s a wide open field with no place to hide from opposing robots, and there’s little chance a tough defending robot is going to receive any penalty points because there aren’t any field obstacles which you can’t push opposing robots into. (Like how in last year’s challenge pushing an opposing team’s robot into the pyramid was illegal.)
So other than pinning, a strictly defensive robot could wreak havoc on slow, weak teams even if they have a good catcher/shooter/passer.
It’s simple. (kill the batman) If your robot can’t stay in one place while catching, shooting, and passing you’re going to have a tough time scoring points. And if your robot is slow and awkward to maneuver, you’re going to have a tough time scoring points.
Hopefully this hybrid drive train will help us to overcome both these obstacles.
Our team wont be machining the parts for each drive module ourselves. We have turned to our partners at Continental Engineering right next door in Chaska Minnesota.
We’ve already sent this design over, and we’re expecting about a one week turnaround for this module of our robot. Once we get all the parts, it will still be up to us to assemble them.
Another great thing about this system is that the entire module can get swapped with an identical module in about five minutes simply by pulling out a few of the exterior bolts. This means that if we were to shear the bolts on any of our wheels, or have something else go terribly wrong, we could be up and running with a replacement module installed in a matter of minutes.
Our team is really excited to see how this new design will work on the robot! It is sure to turn some heads when we roll into competition. We’ll post a picture of the completed module as soon as we’re able.
All the thanks for the concept, designing, and CADing go to Haiming Lou, a very talented member of our team if I do say so myself. He put this thing together in a week almost entirely by himself and with only a few pushes in the right direction by our mentors.
The design was done in a student version of Solid Works 2013-2014.
And yes, that’s plywood there on the outside.
Saved weight on unstressed parts is saved weight on unstressed parts.
