Does using SDS Mk4i swerve modules make an under-bumper intake less feasible? It seems like even if you made a cutout in your drive rail, the bottom plates of the swerve modules would make your effective intake width significantly smaller.
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We’re planning on an under-bumper intake with Mk4i’s. We’re looking at raising the frame member above the modules on that side, and flipping the motors closest to the inside up to the top of the plates. Of course, we just finalized our frame width to 30", which will help too. Feel free to follow along on our OA thread: 2357 System Meltdown | 2024 Open Alliance Build Thread
After thinking for a bit, I’ve come up with a vague design for a flipped front drive rail using a custom waterjet part. I’m guessing this is pretty close to what you were planning.
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In Onshape, the MKCad SDS MK4i swerve has configurations for high and low clearance if you want to take a look:
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We have a encountered the same problem last year for getting on the charge platform. All we did was hack off an inch of the side rail corners to raise the chassis up. The note should fit right under, already tested.
Last year, our frame looked like this:
It worked great. We did that thinking it would help us avoid getting stuck when driving onto the charge station (some early testing showed that this might happen). We also raised our bumpers to the max height allowed by the rules and designed them closer to the minimum bumper dimensions to gain as much ground clearance as possible. With this design, if you set the top of the bumpers at the 7.5" height from the floor and go with 4.5" tall bumpers, you can get about 3" of clearance under the bumper. The top of the frame is 6" above the ground and the bottom of the frame is 4" above the ground.
It worked great for us all season. The bumpers sill provided adequate protection for the motors.
If you are planning to raise one of the frame rails, I would recommend raising all of them to the same height for the following reasons:
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all the structural members will be in the same plane which will avoid any out of plane load transfer through the modules during impacts, driving, etc. The base plate and top plate will sandwich all the frame rails providing a great load transfer structure and stiffness for the chassis. If you only flip one frame rail to the top of the base plate, then the base plate alone carries all the load transfer during an impact.
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it will make integration of the belly pan easier. We mounted the belly pan to the top of the frames with all the electronics mounted to the underside allowing us have a clean top-side for our superstructure. But mounting the belly pan to the bottom of the frame rail would work as well.
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I can see how belly pan integration would be easier. Hacking off an inch of the side rail corners last year was a pain to finish the chassis. Made mounting the Mk4i a little awkward + we usually have a carbon fiber-infilled swerve drive shield we have on top.
This is our solution to increase ground clearance on our mk4i modules:
We added spacers and extended the bolts that connect the wheel mounts to the main pulley by 1/2", and designed a custom intermediate shaft to accommodate this extra length.
These were made on the lathe from 3/8" hex stock.
Edit: Added side by side comparison
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How do you think an under-bumper intake will handle a note that is up against the source wall and caught by a swerve wheel? My team is debating an intake style like this and this is the scenario we’re trying to account for as a potential major con for under-bumper. We’re raising the swerve up to allow for enough clearance, but the modules themselves are the other catch-point. Got to be touch-it-own-it!
We’re considering 3d printed covers for the bottom side of those swerve modules that have an angled part to funnel the note to the center. If you hit a note right on the corner, it won’t go in, but anything inside that should be fine.
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4*30=120 (DUH) 120-1/32 is not rule compliant. It is not an item that inspectors are forgiving on. It is really good idea to be a little under 120" to allow for contingencies
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Just as a side note also, the width of the MK4i is about 2 inches wider (on each side!) than the MK4. Using the non-inverted module will help keep frame width down while keeping the “tunnel” for the note if you’re doing an under bumper intake. Especially if you don’t need the room above the modules.
Well considering my team has already ripped our KOP note this way, I’d say avoid it. My opinion towards under-bumper intake has swayed drastically since proto testing last night.
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The corners of the modules have a small radius to them (they are not sharp corners). So when you wrap the string on a 30"x30" frame with the MK4i’s on the corner, you are actually close to a 1/4" under 120" (we get variations on that depending on the tape measure that is used and how well it bends). I was pleasantly surprised the first time we measured it.
This seems like a really cool upgrade kit for this and future years.
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They only mentioned width, not length.
Pretty easy to build a almost but not quite square bot.
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Polycarbonate guides (like in 111 OA thread for the cadathon) may be another option.
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With swerve how do you decide which is length and with is width?
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