pic: Skunkswerve Module Cross Section



This is the final design for the swerve modules we are using on this year’s robot. I would be happy to answer any questions.

Looks good. How much does it weigh, and can you put up an isometric view? I’m having a hard time visualizing the bearing mounts for the sprocket-bevel gear shaft.

Our design is similar, I’m just curious as to how you guys built it. Our modules are milled and assembled from various pieces of square tubing.

There is a bearing on each side that is press fit. We some left material in the bottom of the hole for the bearing that keeps them from being pressed through. We drilled and tapped the shafts so that we can secure them in the opposite direction with a washer and a bolt. I’m uploading an Iso view right now.

We used 4x4 aluminum extrusion (1/4 W) and 1/4 plate welded to the top. Then our new machining sponsor CNCed out all the holes and add the curve at the bottom that can be seen in an Iso view (Another pic is uploading as I post this).

The Isometric view can be seen here: http://www.chiefdelphi.com/forums/showthread.php?threadid=73090

ok now this is cool, i haven’t seen much people put the split view to work so i gotta give you that.

looks fairly similar to 2022’s swerve modules. Except that we CNCed the parts out of 1/8" aluminum plate and welded them together. So our modules are bigger.

Edit

I’m interested as to how you ensured that the holes for the drive shaft, and other holes that need to be precise, lined up after welding. With most of our welded parts was eperience at least some warping, which is why we chose to have the “cans” welded and then machined.

I was also wondering how large your modules are and how much they weigh for comparison. Thanks in advance.

Each wheelbox has this lazy susan on top and bottom
http://www.mcmaster.com/library/20080826/1544T100L.GIF

I don’t have the exact specs but I am guessing that they are each 8 or 9 inches tall, then +2 inches for the turning chain and drive chain. So the entire drivebase is less than 1 foot tall.

I envy how easy it must be to get your hands inside the module for maintenance. The top of our drive base frame is also about 1’ off the floor, with steering and power chains on top. Do you employ differential power between the left and right side? Our drive does and this allows us to change from “half-swerve” to “crab” to “tank” all without any mechanical changes.

No differential. All wheels are powered the same amount. But we are able to implement a type of “Warthog” steering where to the front wheels turn opposite of the back wheels.

It is fairly easy maintence on the swerve moduals.

We have around a third of an inch of ground clearance.

We use the same type of 4x4x4 or “warthog” drive when we are swerving. We are using a three axis joystick and use x and y to translate or “crab” relative to the front of the robot. When we use the z axis, yawing on the joystick, the modules are oriented “warthog” style AND receive left-right differential power. We have found that this is quite effective.

We also had at 3 axis controller. X and Y for crab steering, twist for warthog.

Excuse my lack of knowledge on Crab Drive, you only needed one CIM because all the wheels move in the same “direction” but the wheel base themselves turn?

Under normal traction circumstances you need at least 2 CIM’s, but with the Regolith 1 CIM is adequate for our team at least.

With a crab drive all of the wheels are oriented in the same direction relative to the field, and all wheels are powered so that the robot moves in that direction. With a pure crab drive there is no way to change the orientation of the robot relative to the field, so most teams implement a turreted manipulator (Team 118 in 2007 and 2008 are good examples). A pure swerve is where all wheels are powered independently AND steered independently so that each wheel can be facing a different direction relative to the field. Our “half swerve” has the front and rear wheels steered together, and the left and right wheels powered together.

Just wondering, did your team do any prototype in the off season? Or were you like us and decide that tank will not work this year in the middle of week 2.