Hey everyone, my team is trying to buy some SDS MK4 swerve modules WITH NEOS before summer, but we don’t know which gear ratio level to go for. We heard that L1 (8.14:1) and L2 (6.75:1) were the most preferable options for a full-weight FRC robot, but we don’t know which to go for between those two. Also, is it possible to simply buy the distinct gears specified in the SDS MK4 parts list to change from one gear ratio to another while keeping the same module? Thanks!
3 Likes
we had l1 and loved it cause we could push pretty much everyone while still being faster than the andymark default ratio.
1 Like
Well did you feel like the L1 was too slow compared to other swerve bots? Was the speed noticeably different?
1 Like
not really to be honest, there were some matches where we had to play defense and while they were a little faster (im assuming they used l2) we had no issues shutting them down. You can’t go wrong with either as long as you’re using falcons for driving.
2 Likes
I see, thanks!
1 Like
We used the L1 gear MK4iS and that was sufficiently fast for our driver (we even had a toggle to drive even slower when intaking)
3 Likes
Did you happen to use falcons or neos?
1 Like
We ran l2 ratio this year and found it to be quite nice. L1 is traction limited so you don’t get much more pushing power or acceleration. The extra free speed of l2 is very helpful for outswerving defenders and general maneuverability, and can still be easily controlled with some driver skill.
7 Likes
Oh I see, thank you!
Might be worthwhile to meetup with a local-ish team and talk to them about their experiences with swerve/test drive their robot.
2 Likes
My team ran L2 (with falcons, not neos). With quite a bit of practice, I was able to control it at full speed and get a significant amount of pushing power from them. I did run most of the season at about an 80% speed limit because L2 can get quite quick if you’re not experienced with swerve driving.
6 Likes
Remember, it’s not all about top speed – acceleration makes a large difference as well. So it’s worth thinking about time/distance to top speed, and it would be nice to have some of this data more readily available. This does bring in the mass/weight of the robot and the number of modules, but it’s reasonable to make assumptions when sharing this data for purposes of comparison.
One way this might be done is for teams/vendors to publish SysId data for a given drivetrain, with the test drivebase weighted to some reasonable total weight.
2 Likes
Besides the obvious cost difference , what are people’s thoughts on Falcons or Neos for SDS modules ?
1 Like
I know the “real” swerve drive people here all preach the gospel of Falcons, but it will be much easier for my team to buy our first swerve and test it this summer if we can use new NEOS and eight Sparkmax that we already own.
$135 per motor less money. $1080 less for four.
And even if we buy new sparkmax controllers, still $55 less per wheel.
2 Likes
Will do, thanks!
Got it, L2 does sound like the sweet spot so far…
I will say that using falcons is much more ideal and maybe in the long run more economical. We have had 3 neos brake, 1 neo 550 brake and 3 sparkMax’s break in the past 3 years. This post is nothing against Neos or Rev (we have still gone back to using neos on everything but the drivetrain) it is just from my expreience that you have to be much more careful with neo’s/neo 550’s. That being said, in @BigK8816 's case, neos seem like the obvious choice.
1 Like
Right, as a rookie team that just finished its first season, my team really shouldn’t be spending more than 2k on any one component of the bot from a sustainable finance perspective. We aren’t fully opposed to going for falcons in reality (pushing the total cost to about $2.6k) since there will always be a way to make up for the extra cost, but where it gets difficult is that we are unable to purchase items over Summer, when the MK4 will most likely get back in stock. If we miss that chance, then we miss the L2 option so yeah we’re trying to see what options we can get as of now.
I don’t think there’s any reason to switch away from Neos if that was your plan.
If you really want to make sure you pick the right ratio I recommend you put some numbers into @JesseK 's iLite drivetrain simulator. You can adjust the parameters to find out what ratio will get you to the end of any given “sprint distance” fastest (including acceleration, wheel slip, current limiting etc.)
TLDR: Anywhere within ~20% of the KOP ratio (10.75:1 on 6" wheels, 7.2:1 on 4" wheels) will pretty much optimize the 15 to 20ft sprint IMO.
1 Like
You want an external encoder for velocity control with a NEO. Other than that, the only differences are wiring, convenience, and price.