It’s small, it weighs about 3.3 lbs, what’s not to love.
Free speed: 17.89 fps
Turning ratio: 131:1 (500 deg/sec free speed). Can be reduced more with more stages on the UP.
Ground Clearance: 3.6" to frame bottom
The steering pinion pulley is interesting: instead of bolting to the provided 16mm bolt circle, I opted to replace the entire output with a 3d printed part. Hopefully, I will have data to show if this actually works soon.
Any reason you wouldn’t mount the steering motor to the bottom plate, and make the steering pulley part of the forks? That would lower your overall height by ~1 inch, and make for a simpler output from the Ultra Planetary.
While it might lower the overall height, it would increase the already high ground clearance even more. At a certain point, the moment loads from that much cantilever would overwhelm the poor .25" delrin bushing I’m using in place of a real bearing.
Also, the space that the pulley already occupies is still needed, because of the gears coming off the driving Neo. The space between plates would remain the same and the ground clearance would increase, only netting me a height saving because the N550 + UP is so tall.
Why would it increase the ground clearance? You don’t have to raise the bottom plate at all - there’s lots of room between it and the wheel axle for a pulley. I agree though that you might have to make the pulley a little larger to fit around the bevel gear. You’d be trading off module width for module height.
I like how you integrated the frame corner piece into the module design. Of course the cut-outs in the frame members to clear the module are going to make them pretty weak in lateral bending but you could easily add additional frame support fingers to the module plate and extend that curved bar on top further along the frame members if you were carrying a lot of the frame rigidity through the corner. If you have a belly pan that picks up the frame fairly close to the module, then what you have is probably more than strong enough.
Looks like you are fairly constrained for drive ratio options given how compact the pinion to module gear is packaged. Any idea what the max and min ratios would be for the various COTS pinion and spur gears that would fit?
We had good success in 2020 with a turning ratio of 33.33:1. So, your ratio of 131:1 is more reduction than you need. You might be able to drop one stage of the UP gearbox. Also, make sure you verify the actual gear ratios of the UP gear set slices. They are not exactly 3:1, 4:1 or 5:1.
I really think,that a bearing for azimuth rotation is the second most important aspect of a swerve module (second only to the bevel gear).
In some of our early in-house designs, we went with bushings and they just never really work out.
I see how you are clamping the main plate between the upper 3D printed part and the machined delrin part. I think it would be relatively easy to integrate a bearing into this design. Instead of clamping the main plate between those two parts, you could clamp the inner race of a bearing with those same two parts and then do something similar to clamp the outer race with the upper part of the clamp being formed by a flanged pocket in the main plate and the other half of the clamp being formed by a 3D printed flanged ring bolted to the main plate.