What do you think is the best drivetrain option for this year. It appears that 6wd drop center drives might have some trouble on the scoring platform because the center wheel will be the only wheel on the platform.
6 or 8wd with no drop and omnis on the front/back. It doesn’t change drive characteristics with different weight/center of mass and has no wobble. It can also easily go over the scoring area and with colsons and vex omnis should grip really nicely.
Make sure you power all wheels with this setup.
Slide/H-drive looks very promising. Without defense their is no worry about being pushed around. For a team with limited resources and expertise, this drive train provides the advantages of horizontal motion without the complexity of swerve or mecanum.
i disagree with this the hump is 2 inches with a 16 degree slope having a 6 wheel drop center should have no problem making it over this in fact it would be beneficial because you would be able to pivot and spin while on top very easily,
a 6 wheel drop center is in the conversation for our team
6in 4 wheel west coast. Make it like a mullet, that is to say business in the front party in the back, or in this case traction in the front omni wheels in the back.
Any drive with strafing has a huge advantage this year. Stacking those totes precisely is hard. Like, really, really hard. I speak from experience there.
I believe that’s the direction my team will take. Our designs have in-frame tote manipulation, and having a four-wheel setup with omnis in front reduces the racking effects of not having a support between the front wheels that would be prevalent with four “tractionful” wheels.
I don’t believe Slide/ H-Drive will be as good as everyone thinks it is, many people are relying on the fact that the horizontal motion will be incredibly helpful. In reality I believe teams will use it as a way of adjusting their precision when needing to stack and line up for totes, which is completely valid until your vision is blocked or you don’t have enough room to strafe. It would be better to build tolerance into your loading mechanisms rather than into your drivetrain where the tote being in the proper orientation is everything. Some teams will attempt to do both (Slide and Any-Orientation intake), we will just have to wait and see in practice which proves to be more effective.
As a team we have done mecanum drives for the past 2 years in FTC but we do not see the value in a mecanum drive or a similar option. To be able to fully utilize a drive train like that you must have a lot of time practicing with it. We are not known for finishing robots quickly so we decided to go with a simple 6WD drive train that we get a lot of practice time on rather than spending a bunch of time on building a completely new drive train.
A. Mecanum robots drive exactly like a first-person shooter. In my experience drivers need maybe ten minutes to acclimate to it.
B. Good call–finishing early and getting good practice time is more important than an “ideal” drive train (whatever that is.)
I agree; strafing would be hugely beneficial.
We pretty much unanimously decided on swerve drive, which is a system we already have experience with.
How is it less complex than mecanum?
Take a look at the 2010 game Breakaway. The bumps in that game were much larger and a lot of team made it over just fine.
Here is one of our videos. (Skip to 0:48)
All questions teams should ask before for selecting a drivetrain:
holonomic or tank drive ?
what size wheels , ground clearance ?
what is the desired speed and torque ?
single speed or shifting gearbox ?
I’m guessing most people think mecanum is complex because thinking about how it moves can hurt your brain initially. And maybe they’re worried about getting the wheel configuration wrong. In reality the most complicated thing is making sure all your wheels hit the ground most of the time, and that weight is relatively evenly distributed (side to side, at the least).
Worst problem I ever had was when someone pulled the PWMs on a mecanum robot we’d misplaced the code for. Working out which PWM was for which wheel was somewhat frustrating for about 30 minutes or so.
Or both (octocanum). Or neither (H slide).
Here’s a procedure that might speed things up a bit.
Put the bot up on blocks.
Command pure forward (FWD), then strafeRight (STR), then rotateClockwise (RCW)… and for each command, record which direction each wheel is turning.
Unplug the PWMs and reinstall them per the attached chart.
This will be the first in quite a few years that we do not use octocanum.
Nor are we using the drop-center WCD-ish drive we prototyped over the summer/fall.