H-drive is one option but you can be pushed around easily. What is a good alternative to swerve this season?
Welcome to ChiefDelphi! It all depends on your team’s resources, especially your expertises coming into the season. I’m not familiar with the supply chains, but it looks like if you don’t already have your hands on COTS Swerve modules, it’ll be hard to get your hands on any this season. It may be similar with mecanum wheels, for instance.
By most measures, it’s very likely that a tank drive of some variety will be the best alternative to swerve this season. In fact by at least some measures (cost, maintainability, coding ease, construction speed) it may be the best drive train overall.
What exact variety of tank drive is best for your team depends on what you want to achieve this year, and there are much better people than me to answer that.
Tank drive - preferably the KOP chassis. Last thing you want to be doing is debugging your drivetrain all season.
A well driven tank drive with some sort of turret or strafing scoring mechanism could get you very far. 254’s 2019 robot comes to mind.
Thank you! That’s what my team is thinking of for the drivetrain, a narrow small tank drive.
This year’s game almost mandates you to use either swerve (and be faster than potential defense) or use a tank drive that is hard to push. I don’t know how calls will be made if an opposing alliance robot pushes you into their community zone, and if that will give them 5 points in fouls, but if that is the case, (which it could be even if a pushed robot is not supposed to be fouled for being in there due to human error) a drive train using mechanum or Omni wheels would likely be a detriment than an advantage as even with the higher maneuverability you’re likely to be pressed into an opposing area, and that is potentially enough to completely change the tide of games
Tank drive with a low COG and some way to have multiple scoring position options. See 5460 / 2767 in 2019 or 3538 / 1619 in 2018. With lower heights you should be able to simply those concepts.
(Being able to score over your back/side to side therefore saving the spin-around time is quite helpful.)
I would be careful putting too much stock in the WCP listed lead times. I have placed several orders for backordered items with listed lead times of a week or 2 and then it was months before I received the items.
112 seems to have come with a good idea to align a tank drive bot to the scoring grids:
AndyMark has SDS modules in stock currently.
Perhaps im just 3 hours late to the party and they were in stock then, but ive just gone through what I believe to be every combination of SDS Swerve on AndyMark (both MK4 and MK4i, assembled and kit form) and everything is showing out of stock.
Given the points associated with being able to stay balanced on the charging station, I’d avoid any drivetrain that tends to slide around when on a slope.
Good ole tank drive. That’s my final answer.
Ahhh, i figured it out, we are both right it seems.
All NEO configurations appear to be out of stock, but falcon configurations appear to be in stock (as you show above).
My team isn’t running SDS modules this year, but for those looking, I wonder if it would be as simple as buying separate/new pinions if you wanted these modules .
We are using Falcon-configuration mk4s with neos on our swerve test bot. I believe we are using the original pinion, modified in some way to fit a neo. @JamesCH95 probably knows more about how exactly we did this.
Yes, we ordered the falcon-based kit near the end of 2022’s regular season, but buying falcons turned into a mess. So one of our sponsors reworked the pinion gears to work with NEOs, which we did have on-hand and were also in stock to refill our our reserve.
This is common knowledge to established FRC community members, but to teams that have not used swerve before (especially rookie teams, of course) I would strongly urge you to avoid attempting to implement swerve mid-season.
I would almost go far as to say that unless you have significant domain history and manpower that you can dedicate solely to the cause, I wouldn’t even attempt to utilize a new model of swerve modules mid-season even if you have past swerve experience with a different model.
There are more than enough challenges to attempt to overcome during the season, and of all of the problems you do not want to have, a robot that won’t move is pretty near the top of the list.
Our team saw more than a handful of teams throughout our district competitions who had stalled themselves, dead-in-the-water, because they attempted to implement swerve mid-season and did not switch back to a different drive train in time.
Instead, experiment with swerve in the off season and build your confidence with the system and all of it’s idiosyncrasies, then come back next year with that in your back-pocket.
So to be fair, there were a lot of factors that led to being able to feild a robot even with this, including but not limited to:
- Multiple excellent software mentors and students
- Robust design process, prototyping, and prioritization prior to starting the “real robot” build
- Not having to go to a week 1 competition
- No other major supply chain limits.
And, we definitely would have wanted more time to continue to refine other things if we had started earlier. We were able to accomplish a big step up in performance between weeks 3 and 5, and the biggest regret we have is not being able to have that extra couple days prior to our week 3 to eek that performance out.
So… I don’t mean to fully disagree. I’m just saying, if you’re going COTS, it’s possible in 2023 to still get something to the field, even with a late start and limited experience. Much more possible than it has been in past years. Don’t underestimate the difficulty. But don’t overestimate it either.
And to be clear, this is a distinct shift in my opinions from a few years back.
I would definitely allow that it is easier in recent years than it ever has been before – which is of course a good thing!
My point though is more-so this: ultimately, swerve is a tool with which to improve the competitiveness of your robot, but it is obviously not the only tool. There are many other tools with a similar reward in increased competitiveness, that take less time to accomplish, and (perhaps more importantly) result in a lower risk to the overall ability of your robot to be able to compete in the first place.