20-04-2008 20:12

Lil' Lavery

Re: pic: vex coaxial swerve

links aren't working (the ... in the middle makes them impossible to copy/paste too)

Interesting design. How do the swerve modules rotate without driving the wheels and vice versa? It appears to be all through the same axle, and unless you have plans on drilling through the vex gears (which you might) in order to make them rotate about the shaft (dead axle), I don't see how it works.

20-04-2008 20:24

Jonathan Norris

Re: pic: vex coaxial swerve

My guess is that the large gears on each assembly are not attached to the axle and just bolted into the U shape to turn, and the axles of each are driven.

20-04-2008 20:51

pacoliketaco

Re: pic: vex coaxial swerve

that was my goal. i think i have enough of those gears to sacrifice 4. although it was suggested on the vexforum that i stabilize the driven shaft more.

20-04-2008 21:23

Andrew Bates

Re: pic: vex coaxial swerve

Nice, did you consider using the actual swerve drive modules? I think you could.

20-04-2008 22:36

gblake

Re: pic: vex coaxial swerve

plt - Here are links to some pics of swerve modules I built. They have the robot chassis supported by 1/4" standoffs that rest on 60-tooth gears that for the tops of the swerve modules. The method might be useful for you.
Pic #0
Pic #1
Pic #2
Pic #3
Pic #4

I want to figure out how to create an even stronger connection between the chassis and swerve modules. I figure that if we were to try to use our designs in a competition, during the pushing and shoving that occurs in them, the axles in our designs (that allow the modules to swerve) will be the point where they bend and break.

I have toyed with the idea of sandwiching an 84-tooth gear between some plates and standoffs. 12-tooth gears around the edges of the 84 could brace it against pure lateral loads and the plates (probably augmented with stand-offs) would prevent twisting about the point where the module's axle enters the chassis frame.

The problem with what I outline above is that if the plates aren't cut to create a circular hole (an annoying expense) that exposes the 84-tooth's mounting holes and allows them to stay exposed as the 84-tooth turns; the connections between the 84-tooth and the rest of the module collide with the framing that holds the 84-tooth (in my imagination ). Maybe you can come up with a rugged way to bring the idea to fruition without ruining too much metal for other purposes.

Blake

20-04-2008 23:34

Andrew Bates

Re: pic: vex coaxial swerve

Something I saw in Atlanta which sounds similar to what you might be trying. A team built a turntable using an 84tooth gear. They had it set right on a large flat plate which gave it stability. From talking to them it sounded like it was actually quite sturdy.

Unfortunately it would appear that I have lost the picture I took. If anyone knows the team that did this please post, they were in franklin I believe.

21-04-2008 00:11

artdutra04

Re: pic: vex coaxial swerve

This looks like a really good start to a coaxial swerve drive.

However, I may offer some advice. One the swerve modules, you may want to consider using angle, C-channel, or a wider plate instead of the single 1x steel bar. The 1x steel bar will most likely flex somewhat, and without any sort of threaded beams (or something similar) between them to lessen the impacts of the flex, it may cause binding issues on the axles.