This year was my teams first year attempting a swerve drive and was by far the most complex, challenging and rigorous thing we have done.
The rest of our robot may not have turned out as well as it should have. I guess this is living proof of the resource draw on us. Even with that this has been our best year with out robot. We won our first engineering awards this year. We also placed the best we have ever as well.
We did not have the strongest of design and engineering so we knew we could not attempt our own fully custom swerve so we used Team 1640s as our launching ground with a few improvements to decrees machining and decrees weight.
Our biggest improvement was using a in line gear box with the drive belt going around the steering motor. Something that allowed us to make it out of a single piece of 2/3 extrusion drastically increasing decreasing weight and increasing the strength much the same way the bends in sheet metal help it stay strong and ridge.
To save even more weight we milled off 1/8 of the .25 thick extrusion on 3 sides allowing the bottom to remain strong to take the hits and such the this game dished out.
All of the upper modules were manually machined holding 2 thousands on all holes and the boring was held at half a thousandth. All laything work was done manual as well holding 1 thousandth all around.
For our prototyping we had printed everything on a 3D printer allowing us to make sure that the gears and such were in line and belt lengths were right.
http://imgur.com/a/Rx370 - Assortment of image’s from the assemble and testing phases.
Our biggest problems and their fixes.
Power we sat still for most of the first district event due to constantly browning out the jag’s thought can bus. Everytime we would try to start steering motors and the drive motors at the same time the resulting voltage drop would take out our can bus. We had 2 fixes for this one was to buy new battery something we had no done for several years. (running 4ish year old battery that are in horrible disrepair on the field was a bad idea). We also devised a system that would not offset every other module by 50-100 milaseconds allowing them to ramp up their electric fields and overcome stall at different times drastically saving our voltage drops.
Encoder slipping. After much post season testing and a bit of disassemble we found that this was due to the press fits that were holding tge coaxle to the pivot top were slipping after awhile this would stop thought so their was no mid season fix. We account this to poor material/poor maching. After post season testing we will be testing them and most lickly new modules will be welded or some other feature.
https://www.youtube.com/watch?v=P_aGnqAmhiw - testing
For programming we used C++ all of our code was custom at least to my knowledge. We did not use field centered control. It was pretty basic but with some driver skill would hold its own. Standard right stick for rotation and left stick for translation.
We did have a really cool feature that would allow us to change our center of rotation on the fly to anywhere with in our robot or out side of our robot allowing us to pull some pretty neat on the fly maneuvering. http://youtu.be/1oVNrp2L1EQ?t=2m26s -best example that i can find on the top of my head.
Even with our limited successes we are moving forward with our development of this drive system. We are mainly attempting to improve our mechanical efficacy and our weight. To do so we are removing the transfer axial from the swerve unit this includes not using chain. http://imgur.com/5fuaJQs
We are hoping that his will improve mechanical efficacy drastically decrees the size of the unit and how tall it is along with how heavy it is.
Any criticism is welcome along with comments to improve design.
Our cad for this years and our designs for next year. https://drive.google.com/folderview?id=0B8s6FomdoczzSkZQV0lhZlk2TGs&usp=drive_web