Hello all! I’m investigating the pros and cons of different drivetrains, namely a custom west coast drive and the kitbot. This summer we (6672 Fusion Corps) have been building our cad/design capabilities in anticipation of the arrival of our new Velox 5050 that will come in the next month or two. I believe the CNC will revolutionize how our team works since before we mostly hand-drafted mechanisms and made up the details as we went, and in the future we will be designing much more of the mechanisms before they are produced. This brings with it a lot more capabilities in producing much better and less janky robots.
First, some context to our situation. In the last three years, we have built good robots that have performed well but not always great. (we’ve had our highlights like ranking number 1 at our rookie regional, winning a district event, and being a captain at worlds this year). However we’ve usually had problems that have plagued our season. In particular, last year our drivetrain suffered horrendously. We were browning out our whole first competition due to a huge amount of scrub from our pneumatic tires and an under-powered gear ratio, with no good way to fix it because of it being the kitbot. We fixed it but the solution was to slow the acceleration of the robot a huge amount. Overall, the drivetrain was what was holding us back last year.
One of the ways we have been exploring pushing our robots to the next level is switching our drivetrain to a west coast drive from the kit bot. An alumni of the team and I designed a WCD over the summer and want to test it out in anticipation of possibly using it during next season. However, the mentors are not totally on board with using it during the season. To help us make a good decision, I am going to go through the Pros and Cons of each and I would like to hear what y’all think.
West Coast Drive:
- Good learning experience and we have the opportunity to make revisions between the fall prototype and the season robot
- Easier to mount mechanisms than the kitbot
- Easier to work with in CAD because you don’t have to worry about wacky imported files
- We made a fully customizeable drivetrain assembly where all you have to input is the variables of the drivetrain and it outputs a full CAD of the drivetrain - so not much time will have to be spent on making a new drivetrain every year (just changing variables to match the game)
- better performance and more flexibility when compared to the kitbot
- I think if we opt out of the kitbot we can use the credits to get other stuff? I’ve been told that but couldn’t find it anywhere on the internet
- more flexibility on gearbox choices (flipped 3 neo, two speed 3 neo etc)
- utilizes our huge investment in the CNC, paves the way to more custom mechanisms
- More maintenance when compared to the kitbot (chain tensioning etc) and we will have to be more vigilant to making sure everything is okay with the drivetrain
- Mentors think it will be very hard and are weary of it already; additionally they think that when I and a senior have graduated the team will not be able to continue with the WCD (I disagree)
- It is not extremely simple like the kitbot
- requires full CAD capabilities on the team, something that we are just now building
- tried and tested, which the mentors like
- Extremely easy to implement, doesn’t take much to get it going as everything is already designed
- We can get it easily and don’t have to cut tube and gussets during the season
- Mostly reliable other than a bad season with it
- very robust
- Not very flexible for things like drivetrain gearboxes in the back/ front or custom/flipped gearboxes
- harder to work with in CAD
- no room to grow
- Harder to mount mechanisms to it (at least less flexibility)
- It did not live up to what we needed last year
- less wheel choices and less custom gearbox opportunites
Also, I was reading the Limelight documentation to try to understand as a build team leader what the programmers need for reliable vision on a robot, and I noticed that the limelight seems to need a stable base (I’m thinking no center drop on the drivetrain) to be most reliable. Does a center drop throw off vision systems when calculating distance to the target? Is it noticeable?
Final word: I want to implement a west coast drive on the team for several reasons:
- I think it will increase our capabilities for custom mechanisms and will utilize the new cnc (my thought is "why do we have the cnc if we aren’t going to use it for game changing things like this)
- I think it will be a good learning experience that can be continued into the future
- we will have greater flexibility in drivetrain design and a higher performance from the drivetrain when compared to the Kitbot
- It is cool to have a custom drivetrain
- I think our team has reached a level of maturity (good amount of students, a lot of support from our school and school alumni, adequate budget, good machining capabilities etc) that will allow us to push our robots to the next level and I think this will be a good first step.
Thanks for reading to those who did… sorry that this was really long What do y’all think? Is it worth it if we can get a prototype working in the fall? should we still go for the Kitbot? I’d love to hear any thoughts.