This is a sketch of a new type of drivetrain. It is similar to nonadrive in that it can be changed from traction to omni wheels midmatch, but uses a different mechanism for doing so. By tilting the entire driverails and putting omni and traction wheels on the same shaft, complexity is taken out of the driverails and put somewhere else. Wheel, motor, and chain placement is nearly unaffected by the BCRDrive, allowing any drivetrain configuration. This is a quick NCAD sketch, the mounting of the center omni obviously needs some work.
I would recommended the shaft lay parallel to the floor in the omni configuration, so the omni wheels will operate more smoothly.
You could retain the use of pneumatics with a similar mechanism.
Also, with the shown mechanism, if the pivot attachment points and the drive hub are not all at the same height, the current setup will result in two different wheel pod angles for each drive hub angle.
Do you plan on running a relatively unmodified drive module that 294 usually runs?
Yeah, the angle is overexagerated in the drawing. Having the omnis as close to level as possible with the treads compensating with more angle might work better, but the quality of my pencil limits my design-in-calculus-class abilities. In a real build, the non-contact wheels would be barely off the ground at all. I hadn’t thought of it before, but yes, the driving hub should be at the same height as the connectors, unless we did something weird with the arm linkage. I had thought about pneumatics, but didn’t know if they would be strong enough, and having a motor gives a lot more control of the angle. In tread mode, it might be nice to put the omnis down just a little bit to make it easier to turn. Some sort of variable traction control.
Right now we want to stick with the Breakaway base, but that could change pretty quick on Saturday morning.
Do you know if the common traction wheels used in FIRST perform the same when tilted a couple degrees? I imagine that it probably wouldn’t because (unlike AM omni’s) their flat to accomidate the tread.
I made up a design sort of similar to yours a while ago. It’s not plausible for a variaty of reasons. Namly: weight and completity. Even so it was fun to do.
http://www.chiefdelphi.com/forums/showthread.php?t=86467
Here it is for your viewing pleasure. (The last post in the Thread)
And all this on the back of a “Cookbook for circular motion problems” page. Good recycling but better luck in the 2011 robot design.
This may actually be feasible if pneumatic wheels were used instead of standard traction wheels. Traction wheels would lose to much traction if tilted in that manner. Pneumatic wheels are rounded; so it’s just a matter of finding the right pairs of wheel sizes that will only contact the ground when it’s desired.
On field, the rotation joints would take a beating. I almost want to say they’d have to be made out of steel or solid aluminum blocks.
Also, when designing this type of drive train in CAD, account for the fact that most of the time the bumpers cannot tilt or raise/lower outside of their specified zones. Thus an outer frame would be needed that connects to the inner frame.
Great idea, I think.
At the very least, a creative one.
Keep exploring this idea! Develop it, iterate it, keep the process going, even if you don’t end up using in competition. It will still be very beneficial to keep working on it.
-Brando
That’s a really cool idea!
If you do, I’d say that you should have a frame around it so that the bumpers don’t tilt out of the bumper zone.
Thaine
that is a really good idea but are you going to be able to do that with only 4CIM motors:ahh: and i would love to see that out on the feild
I’ve played with a robot that had a very similar drive train way back in 2000, it had hard plastic wheels on the outside, high-traction tread in the middle, and saw blades on the inside for ice traction. Not used in FRC competition, unfortunately.
I would recommend using pneumatics to deploy/retract the sides. Have fun with it!
neat idea…
no reason that the pair of wheels couldnt be mounted to the same output shaft of a toughbox or similar… (given that it is of sufficient length)
however…
to make it work well I would think that decreasing the size of the high traction wheels JUST ABIT would be beneficial and planning to tilt the mechanism so that the (the high traction wheels) came into contact with the floor) would be of advantage…
i would also suggest that using pneumatics to drive this would be the best plan of attack…
not sure if we will explore this topic further (team 2229) but its neat…
thanks for sharing.