I was inspired by 148’s and 217’s drivetrain this year, and decided I wanted to try out a similar one. I finished the module, some renders can be found here. Any feedback or suggestions would be great!
So how it works: The main center hole is for the drive shaft to go through. This shaft also serves as the pivot for the whole module. The brackets on top are the mounts for the cylinders that will rotate the module. The skid on the bottom is to prevent both wheels from touching the ground at one time. The traction wheel is geared slow and strong (I haven’t figured out the exact speeds I want yet), while the mecanum is geared really fast.
This is a great way to implement the 148/217 drive train without having to use a wheel in the center and a motor for it. I hope you guys end up doing this because it is a fantastic idea and I am very interested to see how it works out.
I’ve been tossing this one around in my head for a while now. Literally, same idea (fast mecanum, strong traction wheel).
There are pro’s and con’s to putting the traction wheel on the inside vs. outside (being able to turn at all on the traction wheels vs. being unturnable - there are times you could want either).
461 prototyped a similar system (same concept) in the fall. It worked realy well. I will send the IT guys an email and see if we can’t get some pictures or videos posted, though I think we were putting together a white paper.
I’ve been thinking about this for a little while too, I would do it a bit differently, direct driving one of the wheels and pivoting off that. I’m probably going to throw together a CAD of it when my exams are over.
How do you plan on hooking these pods to the robot? Also are you thinking about placing a cim per pod or 2 cims and a gear box somewhere else?
I’ve been thinking about this for a little while too, I would do it a bit differently, direct driving one of the wheels and pivoting off that. I’m probably going to throw together a CAD of it when my exams are over.
Sounds like a good idea but I can think of one potential problem if you were to use this design in a game. If you are pivoting around one wheel that would mean the other wheel would need to be lowered below that wheel thus raising the entire robot. Now depending on how much that raises the robot I can see a situation where the bumpers are no longer in a legal zone. Right?
Must be a popular idea; I’ve also had a design in the works (albeit not something build-able with my kind of resources… more of a Chicken/Wrangler fantasyland robot)
I think it’s a killer concept:
“fast” mode with omnidirectional capability is ideal for offense
“defense” mode gives you four geared down traction wheels in the corners: great for defending and avoiding being pushed while scoring from a stationary point (like you needed to do in 06/07).
Uses only four motors!
I love how you get nearly all of the advantages of a drivetrain with swerve modules, but you don’t suck up so many motors (only four!). Construction could be simpler as well, if some thought is put into design work.
The one major drawback between this design and the one that 148/217 use is the lack of full power being directed to the floor if you get kicked up on just two wheels (like whenever you would be pushing, for instance). However, this can be resolved by engaging/disengaging the two drive motors on one side. This is what I was aiming for in my model, but it wasn’t implemented very well.
PS: If anyone wants a copy of my CAD files, shoot me a PM.
I drew up something similar in 06, modules had traction wheel inner, mecanum outer. Direct drove the tracion wheel which was linked via chain to the mecanum geared up (in hindsight, it’d make more sense to invert the gearing there). Pivoted around the traction wheel shaft.
I’d be stoked if someone built it, I’d love to see it in action.
I think I can get our laser cutting sponsor to cut everything out for it, so hopefully this can be driving in a little bit!
Thanks for all the kind words.
The traction wheels are going to be toward the inside of the robot so that they wont scrub steer. Oh and I forgot to mention that the frame will be done out of 1771’s signature tabbed lasercut baltic birch plywood.
Team 461 built this type of drive during out preseason. But, once the game was released we thought it kind of nullified because we didn’t think it would make it over the bumps.
